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Knowledge Development Knowledge Development Presentation TwoPresentation Two


Knowledge Development 2 - Knowledge Development 2 - 22Main Menu Previous Next

Presentation Two OverviewPresentation Two OverviewPresentation Two OverviewPresentation Two Overview

Equipment IIEquipment II Gas Planning IIGas Planning II Decompression IIDecompression II Techniques and Procedures IITechniques and Procedures II Emergency Procedures IIEmergency Procedures II Team Diving IITeam Diving II Thinking Like a Trimix Diver IIThinking Like a Trimix Diver II Practical Application TwoPractical Application Two



Equipment IIEquipment IIEquipment IIEquipment II

Advantages of Fullface MasksAdvantages of Fullface Masks Considerations for Fullface MasksConsiderations for Fullface Masks Multigas Trimix ComputersMultigas Trimix Computers Planning Dives with a Multigas ComputerPlanning Dives with a Multigas Computer Backups for Multigas ComputersBackups for Multigas Computers

Advantages of Fullface MasksAdvantages of Fullface Masks Considerations for Fullface MasksConsiderations for Fullface Masks Multigas Trimix ComputersMultigas Trimix Computers Planning Dives with a Multigas ComputerPlanning Dives with a Multigas Computer Backups for Multigas ComputersBackups for Multigas Computers


Fullface MasksFullface MasksFullface MasksFullface Masks

What is the primary advantage of using a What is the primary advantage of using a fullface mask for trimix diving?fullface mask for trimix diving?• Primary advantage of using a fullface mask is Primary advantage of using a fullface mask is

to reduce drowning risk in case of CNS to reduce drowning risk in case of CNS convulsion or other loss of consciousnessconvulsion or other loss of consciousness

May allow additional comfort in cold waterMay allow additional comfort in cold water May be fitted with voice communication electronicsMay be fitted with voice communication electronics CNS risk may be higher during trimix dives due to CNS risk may be higher during trimix dives due to

longer decompression - fullface maskslonger decompression - fullface masksmay reduce the risk of drowningmay reduce the risk of drowningshould CNS toxicity occurshould CNS toxicity occur

What is the primary advantage of using a What is the primary advantage of using a fullface mask for trimix diving?fullface mask for trimix diving?• Primary advantage of using a fullface mask is Primary advantage of using a fullface mask is

to reduce drowning risk in case of CNS to reduce drowning risk in case of CNS convulsion or other loss of consciousnessconvulsion or other loss of consciousness

May allow additional comfort in cold waterMay allow additional comfort in cold water May be fitted with voice communication electronicsMay be fitted with voice communication electronics CNS risk may be higher during trimix dives due to CNS risk may be higher during trimix dives due to

longer decompression - fullface maskslonger decompression - fullface masksmay reduce the risk of drowningmay reduce the risk of drowningshould CNS toxicity occurshould CNS toxicity occur


Fullface Mask ConsiderationsFullface Mask ConsiderationsFullface Mask ConsiderationsFullface Mask Considerations

What are two primary considerations in What are two primary considerations in using a fullface mask for trimix diving?using a fullface mask for trimix diving?• Gas switches – you’ll switch gasses, at least for Gas switches – you’ll switch gasses, at least for

air breaksair breaks Use of valving and switch blocks not favoredUse of valving and switch blocks not favored Conventional fullface mask may require entire mask Conventional fullface mask may require entire mask

removal – not typically preferred for tec diving removal – not typically preferred for tec diving continued…continued…

What are two primary considerations in What are two primary considerations in using a fullface mask for trimix diving?using a fullface mask for trimix diving?• Gas switches – you’ll switch gasses, at least for Gas switches – you’ll switch gasses, at least for

air breaksair breaks Use of valving and switch blocks not favoredUse of valving and switch blocks not favored Conventional fullface mask may require entire mask Conventional fullface mask may require entire mask

removal – not typically preferred for tec diving removal – not typically preferred for tec diving continued…continued…


Fullface Mask ConsiderationsFullface Mask ConsiderationsFullface Mask ConsiderationsFullface Mask Considerations

Primary considerations in using a fullface Primary considerations in using a fullface mask for trimix divingmask for trimix diving• Gas sharing – mask should not interfere with Gas sharing – mask should not interfere with

providing gas to a teammateproviding gas to a teammate Conventional mask not suited for gas sharingConventional mask not suited for gas sharing

• Fullface mask tec compatibilityFullface mask tec compatibility Allows for use of standard secondAllows for use of standard second

stages and no significantstages and no significantprocedural changesprocedural changes

Primary considerations in using a fullface Primary considerations in using a fullface mask for trimix divingmask for trimix diving• Gas sharing – mask should not interfere with Gas sharing – mask should not interfere with

providing gas to a teammateproviding gas to a teammate Conventional mask not suited for gas sharingConventional mask not suited for gas sharing

• Fullface mask tec compatibilityFullface mask tec compatibility Allows for use of standard secondAllows for use of standard second

stages and no significantstages and no significantprocedural changesprocedural changes


Multigas Trimix ComputersMultigas Trimix ComputersMultigas Trimix ComputersMultigas Trimix Computers

What are two primary advantages of What are two primary advantages of diving with a multigas trimix computer?diving with a multigas trimix computer?• Several trimix computers on the marketSeveral trimix computers on the market

Can be programmed with seven or more gas blendsCan be programmed with seven or more gas blends Computer calculates decompression based on actual Computer calculates decompression based on actual

dive depth, time and gassesdive depth, time and gasses Some interface with desktop deco softwareSome interface with desktop deco software

• AdvantagesAdvantages Precision - deco schedule based on actualPrecision - deco schedule based on actual

dive profiledive profile Simplifies some emergency situationsSimplifies some emergency situations

What are two primary advantages of What are two primary advantages of diving with a multigas trimix computer?diving with a multigas trimix computer?• Several trimix computers on the marketSeveral trimix computers on the market

Can be programmed with seven or more gas blendsCan be programmed with seven or more gas blends Computer calculates decompression based on actual Computer calculates decompression based on actual

dive depth, time and gassesdive depth, time and gasses Some interface with desktop deco softwareSome interface with desktop deco software

• AdvantagesAdvantages Precision - deco schedule based on actualPrecision - deco schedule based on actual

dive profiledive profile Simplifies some emergency situationsSimplifies some emergency situations


Planning Dives - Multigas ComputerPlanning Dives - Multigas ComputerPlanning Dives - Multigas ComputerPlanning Dives - Multigas Computer

How do you plan dives with a multigas How do you plan dives with a multigas computer?computer?• Plan dives using desktop deco softwarePlan dives using desktop deco software

Multigas dive computers do not calculate gas supply Multigas dive computers do not calculate gas supply requirementsrequirements

Predive planning modes don’t allow for easy Predive planning modes don’t allow for easy comparison of differing gases, depths etc.comparison of differing gases, depths etc.

Have backup tables Have backup tables continued…continued…

How do you plan dives with a multigas How do you plan dives with a multigas computer?computer?• Plan dives using desktop deco softwarePlan dives using desktop deco software

Multigas dive computers do not calculate gas supply Multigas dive computers do not calculate gas supply requirementsrequirements

Predive planning modes don’t allow for easy Predive planning modes don’t allow for easy comparison of differing gases, depths etc.comparison of differing gases, depths etc.

Have backup tables Have backup tables continued…continued…


Planning Dives - Multigas ComputerPlanning Dives - Multigas ComputerPlanning Dives - Multigas ComputerPlanning Dives - Multigas Computer

Planning divesPlanning dives• Learn which desktop deco software algorithm Learn which desktop deco software algorithm

most closely matches multigas computermost closely matches multigas computer Start conservativeStart conservative

Planning divesPlanning dives• Learn which desktop deco software algorithm Learn which desktop deco software algorithm

most closely matches multigas computermost closely matches multigas computer Start conservativeStart conservative


Backups for Multigas ComputersBackups for Multigas ComputersBackups for Multigas ComputersBackups for Multigas Computers

How do you backup a multigas computer How do you backup a multigas computer when diving with trimix?when diving with trimix?• Simplest backup method – have two multigas Simplest backup method – have two multigas

computerscomputers Two computers are seldom identical – decompress Two computers are seldom identical – decompress

according to most conservativeaccording to most conservative

• With only one computer - carry contingency With only one computer - carry contingency tables generated by desktop deco softwaretables generated by desktop deco software

• Even with two computers – carryEven with two computers – carrycontingency tables as backups contingency tables as backups

How do you backup a multigas computer How do you backup a multigas computer when diving with trimix?when diving with trimix?• Simplest backup method – have two multigas Simplest backup method – have two multigas

computerscomputers Two computers are seldom identical – decompress Two computers are seldom identical – decompress

according to most conservativeaccording to most conservative

• With only one computer - carry contingency With only one computer - carry contingency tables generated by desktop deco softwaretables generated by desktop deco software

• Even with two computers – carryEven with two computers – carrycontingency tables as backups contingency tables as backups


Gas Planning IIGas Planning IIGas Planning IIGas Planning II

Characteristics of HeliumCharacteristics of Helium Primary Advantages of HeliumPrimary Advantages of Helium Disadvantages of HeliumDisadvantages of Helium Equivalent Narcotic DepthEquivalent Narcotic Depth Selecting a TrimixSelecting a Trimix The Ideal MixThe Ideal Mix Hypoxic TrimixHypoxic Trimix Travel GasTravel Gas Repetitive Dives and TrimixRepetitive Dives and Trimix

Characteristics of HeliumCharacteristics of Helium Primary Advantages of HeliumPrimary Advantages of Helium Disadvantages of HeliumDisadvantages of Helium Equivalent Narcotic DepthEquivalent Narcotic Depth Selecting a TrimixSelecting a Trimix The Ideal MixThe Ideal Mix Hypoxic TrimixHypoxic Trimix Travel GasTravel Gas Repetitive Dives and TrimixRepetitive Dives and Trimix


Characteristics of HeliumCharacteristics of HeliumCharacteristics of HeliumCharacteristics of Helium

What four characteristics of helium relate What four characteristics of helium relate to its use as a dive gas?to its use as a dive gas?• Helium doesn’t dissolve in lipids as readily as Helium doesn’t dissolve in lipids as readily as

nitrogen or oxygennitrogen or oxygen• Helium is less dense than nitrogen or oxygenHelium is less dense than nitrogen or oxygen• Helium diffuses more rapidly than nitrogen or Helium diffuses more rapidly than nitrogen or

oxygenoxygen• Helium conducts heat faster thanHelium conducts heat faster than

nitrogen/oxygennitrogen/oxygen

What four characteristics of helium relate What four characteristics of helium relate to its use as a dive gas?to its use as a dive gas?• Helium doesn’t dissolve in lipids as readily as Helium doesn’t dissolve in lipids as readily as

nitrogen or oxygennitrogen or oxygen• Helium is less dense than nitrogen or oxygenHelium is less dense than nitrogen or oxygen• Helium diffuses more rapidly than nitrogen or Helium diffuses more rapidly than nitrogen or

oxygenoxygen• Helium conducts heat faster thanHelium conducts heat faster than

nitrogen/oxygennitrogen/oxygen


Primary Advantages of HeliumPrimary Advantages of HeliumPrimary Advantages of HeliumPrimary Advantages of Helium

What are the two primary advantages of What are the two primary advantages of helium as a dive gas?helium as a dive gas?• Helium doesn’t cause narcosis within Tec Diver Helium doesn’t cause narcosis within Tec Diver

depthsdepths Due to poor lipid solubilityDue to poor lipid solubility Can cause High Pressure Nervous Syndrome but Can cause High Pressure Nervous Syndrome but

typically not in Tec Diver depths – generally below typically not in Tec Diver depths – generally below 125 m/400 ft.125 m/400 ft.

• Helium requires less effort to breathe,Helium requires less effort to breathe,reduces fatigue and saves energyreduces fatigue and saves energy

What are the two primary advantages of What are the two primary advantages of helium as a dive gas?helium as a dive gas?• Helium doesn’t cause narcosis within Tec Diver Helium doesn’t cause narcosis within Tec Diver

depthsdepths Due to poor lipid solubilityDue to poor lipid solubility Can cause High Pressure Nervous Syndrome but Can cause High Pressure Nervous Syndrome but

typically not in Tec Diver depths – generally below typically not in Tec Diver depths – generally below 125 m/400 ft.125 m/400 ft.

• Helium requires less effort to breathe,Helium requires less effort to breathe,reduces fatigue and saves energyreduces fatigue and saves energy


Disadvantages of HeliumDisadvantages of HeliumDisadvantages of HeliumDisadvantages of Helium

What are four disadvantages What are four disadvantages of helium as a dive gas?of helium as a dive gas?• Helium’s rapid diffusion makes Helium’s rapid diffusion makes

trimix dives longer because trimix dives longer because more gas goes into solution more gas goes into solution and must come out of solution and must come out of solution during decompressionduring decompression

Helium may ingas faster than outgas Helium may ingas faster than outgas therefore it takes longer to therefore it takes longer to decompress decompress continued…continued…

What are four disadvantages What are four disadvantages of helium as a dive gas?of helium as a dive gas?• Helium’s rapid diffusion makes Helium’s rapid diffusion makes

trimix dives longer because trimix dives longer because more gas goes into solution more gas goes into solution and must come out of solution and must come out of solution during decompressionduring decompression

Helium may ingas faster than outgas Helium may ingas faster than outgas therefore it takes longer to therefore it takes longer to decompress decompress continued…continued…



Second disadvantage of Second disadvantage of helium as a dive gashelium as a dive gas• Helium’s rapid diffusion Helium’s rapid diffusion

makes helium less forgiving makes helium less forgiving compared to air in case of compared to air in case of decompression errorsdecompression errors

Helium forms bubbles more Helium forms bubbles more rapidly therefore less error rapidly therefore less error tolerance tolerance continued…continued…

Second disadvantage of Second disadvantage of helium as a dive gashelium as a dive gas• Helium’s rapid diffusion Helium’s rapid diffusion

makes helium less forgiving makes helium less forgiving compared to air in case of compared to air in case of decompression errorsdecompression errors

Helium forms bubbles more Helium forms bubbles more rapidly therefore less error rapidly therefore less error tolerance tolerance continued…continued…



Third disadvantage of helium as a dive gasThird disadvantage of helium as a dive gas • Helium’s rapid diffusion rate makes isobaric Helium’s rapid diffusion rate makes isobaric

counterdiffusion (inert gas counterdiffusion) a counterdiffusion (inert gas counterdiffusion) a theoretical concerntheoretical concern

An issue if switching from a slow diffusing gas to a fast An issue if switching from a slow diffusing gas to a fast diffusing gas during decompressiondiffusing gas during decompression

Generally not an issue as standardGenerally not an issue as standardpractice is switching from a fast diffusingpractice is switching from a fast diffusinggas to a slow diffusing gas gas to a slow diffusing gas

Gas compatibility between teammatesGas compatibility between teammatesis important is important continued…continued…

Third disadvantage of helium as a dive gasThird disadvantage of helium as a dive gas • Helium’s rapid diffusion rate makes isobaric Helium’s rapid diffusion rate makes isobaric


An issue if switching from a slow diffusing gas to a fast An issue if switching from a slow diffusing gas to a fast diffusing gas during decompressiondiffusing gas during decompression

Generally not an issue as standardGenerally not an issue as standardpractice is switching from a fast diffusingpractice is switching from a fast diffusinggas to a slow diffusing gas gas to a slow diffusing gas

Gas compatibility between teammatesGas compatibility between teammatesis important is important continued…continued…



What is isobaric counterdiffusion and how What is isobaric counterdiffusion and how do you avoid it?do you avoid it?• Helium’s rapid diffusion rate makes isobaric Helium’s rapid diffusion rate makes isobaric


Isobaric counterdiffusion can also be an issue by Isobaric counterdiffusion can also be an issue by causing DCS through counter diffusion through skin if causing DCS through counter diffusion through skin if surrounded by rapidly diffusing gassurrounded by rapidly diffusing gas(helium/TMx) while breathing a slow(helium/TMx) while breathing a slowdiffusing gas (air/EANx)diffusing gas (air/EANx)

Don’t put helium in your dry suitDon’t put helium in your dry suit

What is isobaric counterdiffusion and how What is isobaric counterdiffusion and how do you avoid it?do you avoid it?• Helium’s rapid diffusion rate makes isobaric Helium’s rapid diffusion rate makes isobaric


Isobaric counterdiffusion can also be an issue by Isobaric counterdiffusion can also be an issue by causing DCS through counter diffusion through skin if causing DCS through counter diffusion through skin if surrounded by rapidly diffusing gassurrounded by rapidly diffusing gas(helium/TMx) while breathing a slow(helium/TMx) while breathing a slowdiffusing gas (air/EANx)diffusing gas (air/EANx)

Don’t put helium in your dry suitDon’t put helium in your dry suit



What is the fourth disadvantage What is the fourth disadvantage of helium as a dive gas and how of helium as a dive gas and how can putting trimix in your dry suit can putting trimix in your dry suit cause a decompression problem?cause a decompression problem?• Helium’s heat absorbing Helium’s heat absorbing

characteristics and isobaric characteristics and isobaric counterdiffusion make it counterdiffusion make it inappropriate for dry suitinappropriate for dry suitinflation gasinflation gas

Argon is most common because it is aArgon is most common because it is abetter insulatorbetter insulator

Add an inflator hose on a deco cylinderAdd an inflator hose on a deco cylinderfor backupfor backup

What is the fourth disadvantage What is the fourth disadvantage of helium as a dive gas and how of helium as a dive gas and how can putting trimix in your dry suit can putting trimix in your dry suit cause a decompression problem?cause a decompression problem?• Helium’s heat absorbing Helium’s heat absorbing

characteristics and isobaric characteristics and isobaric counterdiffusion make it counterdiffusion make it inappropriate for dry suitinappropriate for dry suitinflation gasinflation gas

Argon is most common because it is aArgon is most common because it is abetter insulatorbetter insulator

Add an inflator hose on a deco cylinderAdd an inflator hose on a deco cylinderfor backupfor backup


ENDs - Equivalent Narcotic DepthsENDs - Equivalent Narcotic DepthsENDs - Equivalent Narcotic DepthsENDs - Equivalent Narcotic Depths

What is an END (Equivalent Narcotic Depth), What is an END (Equivalent Narcotic Depth), and how do you determine it?and how do you determine it?• ENDs is the depth you would expect the same ENDs is the depth you would expect the same

narcosis if diving with airnarcosis if diving with air Because oxygen appears to be as or slightly more Because oxygen appears to be as or slightly more

narcotic than nitrogen, the prevailing method isnarcotic than nitrogen, the prevailing method isto treat oxygen as narcotic to treat oxygen as narcotic

Desktop software usually determines ENDs Desktop software usually determines ENDs continued…continued…

What is an END (Equivalent Narcotic Depth), What is an END (Equivalent Narcotic Depth), and how do you determine it?and how do you determine it?• ENDs is the depth you would expect the same ENDs is the depth you would expect the same

narcosis if diving with airnarcosis if diving with air Because oxygen appears to be as or slightly more Because oxygen appears to be as or slightly more

narcotic than nitrogen, the prevailing method isnarcotic than nitrogen, the prevailing method isto treat oxygen as narcotic to treat oxygen as narcotic

Desktop software usually determines ENDs Desktop software usually determines ENDs continued…continued…


ENDs - Equivalent Narcotic DepthsENDs - Equivalent Narcotic DepthsENDs - Equivalent Narcotic DepthsENDs - Equivalent Narcotic Depths

What is an END (Equivalent Narcotic What is an END (Equivalent Narcotic Depth), and how do you determine it?Depth), and how do you determine it?• Calculated by:Calculated by:

Finding the absolute partial pressure of the Finding the absolute partial pressure of the nitrogen/oxygen portion of trimix at a given depthnitrogen/oxygen portion of trimix at a given depth

Determining the depth at which thatDetermining the depth at which thatpartial pressure is the total pressurepartial pressure is the total pressure

What is an END (Equivalent Narcotic What is an END (Equivalent Narcotic Depth), and how do you determine it?Depth), and how do you determine it?• Calculated by:Calculated by:

Finding the absolute partial pressure of the Finding the absolute partial pressure of the nitrogen/oxygen portion of trimix at a given depthnitrogen/oxygen portion of trimix at a given depth

Determining the depth at which thatDetermining the depth at which thatpartial pressure is the total pressurepartial pressure is the total pressure

MetricExample

ImperialExample

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ENDs Metric ExampleENDs Metric ExampleENDs Metric ExampleENDs Metric Example

END = [1-frantion of He) X (D + 10)] -10END = [1-frantion of He) X (D + 10)] -10

What is the END at 50 metres when diving What is the END at 50 metres when diving TMx 18/33?TMx 18/33?• END = [(1-.33) X (50 + 10)] -10END = [(1-.33) X (50 + 10)] -10• END = [(.67) X (60)] - 10END = [(.67) X (60)] - 10• END = 40.2 - 10END = 40.2 - 10• END = 30.2 metresEND = 30.2 metres


What is the END at 50 metres when diving What is the END at 50 metres when diving TMx 18/33?TMx 18/33?• END = [(1-.33) X (50 + 10)] -10END = [(1-.33) X (50 + 10)] -10• END = [(.67) X (60)] - 10END = [(.67) X (60)] - 10• END = 40.2 - 10END = 40.2 - 10• END = 30.2 metresEND = 30.2 metres

Imperial Example

NextPrevious


ENDs Imperial ExampleENDs Imperial ExampleENDs Imperial ExampleENDs Imperial Example


What is the END at 165 feet when diving What is the END at 165 feet when diving TMx 18/33?TMx 18/33?• END = [(1-.33) X (165 + 33)] -33END = [(1-.33) X (165 + 33)] -33• END = [(.67) X (198)] -33END = [(.67) X (198)] -33• END = 132.7 – 33END = 132.7 – 33• END = 99.7 feetEND = 99.7 feet


What is the END at 165 feet when diving What is the END at 165 feet when diving TMx 18/33?TMx 18/33?• END = [(1-.33) X (165 + 33)] -33END = [(1-.33) X (165 + 33)] -33• END = [(.67) X (198)] -33END = [(.67) X (198)] -33• END = 132.7 – 33END = 132.7 – 33• END = 99.7 feetEND = 99.7 feet

MetricExample

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Selecting a TrimixSelecting a TrimixSelecting a TrimixSelecting a Trimix

What four considerations do you apply in What four considerations do you apply in selecting a trimix?selecting a trimix?• Several factors go into selecting the gasses Several factors go into selecting the gasses

you will use and at what depth you will make you will use and at what depth you will make gas switches gas switches continued…continued…

What four considerations do you apply in What four considerations do you apply in selecting a trimix?selecting a trimix?• Several factors go into selecting the gasses Several factors go into selecting the gasses

you will use and at what depth you will make you will use and at what depth you will make gas switches gas switches continued…continued…

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Considerations in Considerations in selecting a trimix:selecting a trimix:• Narcosis – maximum Narcosis – maximum

tolerable narcosistolerable narcosis Recommend END 40 Recommend END 40

metres/130 feetmetres/130 feet

• Oxygen exposureOxygen exposure Bottom oxygen partial Bottom oxygen partial

pressurepressure Total CNS clock and Total CNS clock and

OUT exposures OUT exposures continued…continued…

Considerations in Considerations in selecting a trimix:selecting a trimix:• Narcosis – maximum Narcosis – maximum

tolerable narcosistolerable narcosis Recommend END 40 Recommend END 40

metres/130 feetmetres/130 feet

• Oxygen exposureOxygen exposure Bottom oxygen partial Bottom oxygen partial

pressurepressure Total CNS clock and Total CNS clock and

OUT exposures OUT exposures continued…continued…



Considerations in selecting a trimix:Considerations in selecting a trimix:• Decompression issuesDecompression issues

Decompression duration – thermal considerationDecompression duration – thermal consideration Ample gasAmple gas

• LogisticsLogistics SubstantialSubstantial

advantages of someadvantages of somegas blends (availablegas blends (availablepremix to savepremix to savetime/cost, time/cost, available tables)available tables)

Considerations in selecting a trimix:Considerations in selecting a trimix:• Decompression issuesDecompression issues

Decompression duration – thermal considerationDecompression duration – thermal consideration Ample gasAmple gas

• LogisticsLogistics SubstantialSubstantial

advantages of someadvantages of somegas blends (availablegas blends (availablepremix to savepremix to savetime/cost, time/cost, available tables)available tables)


The Ideal TrimixThe Ideal TrimixThe Ideal TrimixThe Ideal Trimix

What is meant by “ideal What is meant by “ideal mix”? mix”? • Ideal trimix has an oxygen Ideal trimix has an oxygen

percentage that yields a PO2 percentage that yields a PO2 of 1.4 and an END of 40 of 1.4 and an END of 40 metres/130 feet at the metres/130 feet at the planned depthplanned depth

Ideal trimix has the shortest Ideal trimix has the shortest decompression for depthdecompression for depthbased on highestbased on highestpossible oxygenpossible oxygencontent and lowest content and lowest possible heliumpossible heliumcontent content continued…continued…

What is meant by “ideal What is meant by “ideal mix”? mix”? • Ideal trimix has an oxygen Ideal trimix has an oxygen

percentage that yields a PO2 percentage that yields a PO2 of 1.4 and an END of 40 of 1.4 and an END of 40 metres/130 feet at the metres/130 feet at the planned depthplanned depth

Ideal trimix has the shortest Ideal trimix has the shortest decompression for depthdecompression for depthbased on highestbased on highestpossible oxygenpossible oxygencontent and lowest content and lowest possible heliumpossible heliumcontent content continued…continued…



Find the ideal trimix by using the Find the ideal trimix by using the Maximum Depth Table and the EquivalentMaximum Depth Table and the EquivalentNarcotic Depth TableNarcotic Depth Table• Maximum Depth Table – follow 1.4 column to Maximum Depth Table – follow 1.4 column to

desired depth (next greater), follow row left to desired depth (next greater), follow row left to oxygen percent in right columnoxygen percent in right column

• Equivalent Narcotic Depth Table – follow depth Equivalent Narcotic Depth Table – follow depth column for planned depth (next shallower), column for planned depth (next shallower), then follow row left to the heliumthen follow row left to the heliumpercentage in right column percentage in right column

Find the ideal trimix by using the Find the ideal trimix by using the Maximum Depth Table and the EquivalentMaximum Depth Table and the EquivalentNarcotic Depth TableNarcotic Depth Table• Maximum Depth Table – follow 1.4 column to Maximum Depth Table – follow 1.4 column to

desired depth (next greater), follow row left to desired depth (next greater), follow row left to oxygen percent in right columnoxygen percent in right column

• Equivalent Narcotic Depth Table – follow depth Equivalent Narcotic Depth Table – follow depth column for planned depth (next shallower), column for planned depth (next shallower), then follow row left to the heliumthen follow row left to the heliumpercentage in right column percentage in right column

ExampleQuestion

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Question: The Ideal TrimixQuestion: The Ideal TrimixQuestion: The Ideal TrimixQuestion: The Ideal Trimix

What is the ideal trimix for 64 metres/210 What is the ideal trimix for 64 metres/210 feet?feet?• In the Maximum Depth Table, in the 1.4 In the Maximum Depth Table, in the 1.4

column find 64 metres/210 feetcolumn find 64 metres/210 feet Go to the left and find 19 percentGo to the left and find 19 percent

• Find the 66 metre (rounding up from 64)/210 Find the 66 metre (rounding up from 64)/210 foot depth column on the Equivalent Narcotic foot depth column on the Equivalent Narcotic Depth TableDepth Table

Follow it down to 40 metres/130 feetFollow it down to 40 metres/130 feet Go left to find 34 percent (metric)/33Go left to find 34 percent (metric)/33

percent (imperial) helium percent (imperial) helium continued…continued…

What is the ideal trimix for 64 metres/210 What is the ideal trimix for 64 metres/210 feet?feet?• In the Maximum Depth Table, in the 1.4 In the Maximum Depth Table, in the 1.4

column find 64 metres/210 feetcolumn find 64 metres/210 feet Go to the left and find 19 percentGo to the left and find 19 percent

• Find the 66 metre (rounding up from 64)/210 Find the 66 metre (rounding up from 64)/210 foot depth column on the Equivalent Narcotic foot depth column on the Equivalent Narcotic Depth TableDepth Table

Follow it down to 40 metres/130 feetFollow it down to 40 metres/130 feet Go left to find 34 percent (metric)/33Go left to find 34 percent (metric)/33

percent (imperial) helium percent (imperial) helium continued…continued…


Answer: The Ideal TrimixAnswer: The Ideal TrimixAnswer: The Ideal TrimixAnswer: The Ideal Trimix

The ideal trimix would be –The ideal trimix would be –• TMx 19/34 metricTMx 19/34 metric• TMx 19/33 imperialTMx 19/33 imperial

The ideal trimix would be –The ideal trimix would be –• TMx 19/34 metricTMx 19/34 metric• TMx 19/33 imperialTMx 19/33 imperial



For what reason is the “ideal mix” often For what reason is the “ideal mix” often not ideal?not ideal?• The ideal mix is The ideal mix is notnot often ideal often ideal

Doesn’t consider oxygen exposure – may be useful to Doesn’t consider oxygen exposure – may be useful to have less oxygen to minimize CNS “clock” and OTUs, have less oxygen to minimize CNS “clock” and OTUs, especially when making repetitive dives or multiday especially when making repetitive dives or multiday divesdives

• Better to deco longer than to push your oxygen limitsBetter to deco longer than to push your oxygen limits Mission may call for more conservative narcotic limit Mission may call for more conservative narcotic limit

of 30 metres/100 feet END or shallowerof 30 metres/100 feet END or shallower Seldom a blend divers commonly useSeldom a blend divers commonly use

For what reason is the “ideal mix” often For what reason is the “ideal mix” often not ideal?not ideal?• The ideal mix is The ideal mix is notnot often ideal often ideal

Doesn’t consider oxygen exposure – may be useful to Doesn’t consider oxygen exposure – may be useful to have less oxygen to minimize CNS “clock” and OTUs, have less oxygen to minimize CNS “clock” and OTUs, especially when making repetitive dives or multiday especially when making repetitive dives or multiday divesdives

• Better to deco longer than to push your oxygen limitsBetter to deco longer than to push your oxygen limits Mission may call for more conservative narcotic limit Mission may call for more conservative narcotic limit

of 30 metres/100 feet END or shallowerof 30 metres/100 feet END or shallower Seldom a blend divers commonly useSeldom a blend divers commonly use

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Hypoxic TrimixHypoxic TrimixHypoxic TrimixHypoxic Trimix

What is meant by a “hypoxic” trimix?What is meant by a “hypoxic” trimix?• ““Hypoxic” trimix means “low oxygen”Hypoxic” trimix means “low oxygen”

““Hypoxic trimix” means a trimix with less than 21 Hypoxic trimix” means a trimix with less than 21 percent oxygenpercent oxygen

18 percent oxygen is the recommended minimum 18 percent oxygen is the recommended minimum use at the surfaceuse at the surface

As low as 16 percent can be breathed at the surfaceAs low as 16 percent can be breathed at the surface Trimix with as little as 10.5 percent oxygen is Trimix with as little as 10.5 percent oxygen is

common for deeper exploration common for deeper exploration continued…continued…

What is meant by a “hypoxic” trimix?What is meant by a “hypoxic” trimix?• ““Hypoxic” trimix means “low oxygen”Hypoxic” trimix means “low oxygen”

““Hypoxic trimix” means a trimix with less than 21 Hypoxic trimix” means a trimix with less than 21 percent oxygenpercent oxygen

18 percent oxygen is the recommended minimum 18 percent oxygen is the recommended minimum use at the surfaceuse at the surface

As low as 16 percent can be breathed at the surfaceAs low as 16 percent can be breathed at the surface Trimix with as little as 10.5 percent oxygen is Trimix with as little as 10.5 percent oxygen is

common for deeper exploration common for deeper exploration continued…continued…


Hypoxic TrimixHypoxic TrimixHypoxic TrimixHypoxic Trimix

More on “hypoxic” trimixMore on “hypoxic” trimix ““Although the blend may have insufficient oxygen Although the blend may have insufficient oxygen

PO2 to breathe at the surface, it does at depth due to PO2 to breathe at the surface, it does at depth due to increased partial pressure at depthincreased partial pressure at depth

• Hypoxic trimix is used to reduceHypoxic trimix is used to reduceoxygen exposure on deeper divesoxygen exposure on deeper dives

More on “hypoxic” trimixMore on “hypoxic” trimix ““Although the blend may have insufficient oxygen Although the blend may have insufficient oxygen

PO2 to breathe at the surface, it does at depth due to PO2 to breathe at the surface, it does at depth due to increased partial pressure at depthincreased partial pressure at depth

• Hypoxic trimix is used to reduceHypoxic trimix is used to reduceoxygen exposure on deeper divesoxygen exposure on deeper dives


Travel GasTravel GasTravel GasTravel Gas

What is a “travel gas”?What is a “travel gas”?• Travel gas is a higher oxygen mix used until Travel gas is a higher oxygen mix used until

reaching a depth deep enough to use trimixreaching a depth deep enough to use trimix• Failure to use travel gas can cause loss of Failure to use travel gas can cause loss of

consciousnessconsciousness• Use travel gas until you reach a depth at which Use travel gas until you reach a depth at which

you have a PO2 of .16 ata or greater with you have a PO2 of .16 ata or greater with bottom gas bottom gas continued…continued…

What is a “travel gas”?What is a “travel gas”?• Travel gas is a higher oxygen mix used until Travel gas is a higher oxygen mix used until

reaching a depth deep enough to use trimixreaching a depth deep enough to use trimix• Failure to use travel gas can cause loss of Failure to use travel gas can cause loss of

consciousnessconsciousness• Use travel gas until you reach a depth at which Use travel gas until you reach a depth at which

you have a PO2 of .16 ata or greater with you have a PO2 of .16 ata or greater with bottom gas bottom gas continued…continued…


Travel GasTravel GasTravel GasTravel Gas

More on “travel gas”More on “travel gas”• Community practice is to use some of the Community practice is to use some of the

lowest oxygen deco gas for travel gas lowest oxygen deco gas for travel gas (example EANX 36)(example EANX 36)

• Travel gas may be an intermediate depthTravel gas may be an intermediate depthtrimix or enriched air nitroxtrimix or enriched air nitrox

• Travel gas may be used as decompression gas, Travel gas may be used as decompression gas, especially for some of the deep stopsespecially for some of the deep stops

More on “travel gas”More on “travel gas”• Community practice is to use some of the Community practice is to use some of the

lowest oxygen deco gas for travel gas lowest oxygen deco gas for travel gas (example EANX 36)(example EANX 36)

• Travel gas may be an intermediate depthTravel gas may be an intermediate depthtrimix or enriched air nitroxtrimix or enriched air nitrox

• Travel gas may be used as decompression gas, Travel gas may be used as decompression gas, especially for some of the deep stopsespecially for some of the deep stops


Back GasBack GasBack GasBack Gas

When do you need a travel gas?When do you need a travel gas?• If you need travel gas on the way down you’ll If you need travel gas on the way down you’ll

need it on the way backupneed it on the way backup• Handle travel gas like any other stage/deco Handle travel gas like any other stage/deco

gas – NO TOX switchesgas – NO TOX switches• Can’t use back gas between switches when Can’t use back gas between switches when

above back gas minimum depth,above back gas minimum depth,use travel gas between deco cylindersuse travel gas between deco cylinders

• High exertion or diving at altitude,High exertion or diving at altitude,16 to 18 percent oxygen may be16 to 18 percent oxygen may betoo low – use a travel gas withtoo low – use a travel gas with21 percent or more oxygen 21 percent or more oxygen continued…continued…

When do you need a travel gas?When do you need a travel gas?• If you need travel gas on the way down you’ll If you need travel gas on the way down you’ll

need it on the way backupneed it on the way backup• Handle travel gas like any other stage/deco Handle travel gas like any other stage/deco

gas – NO TOX switchesgas – NO TOX switches• Can’t use back gas between switches when Can’t use back gas between switches when

above back gas minimum depth,above back gas minimum depth,use travel gas between deco cylindersuse travel gas between deco cylinders

• High exertion or diving at altitude,High exertion or diving at altitude,16 to 18 percent oxygen may be16 to 18 percent oxygen may betoo low – use a travel gas withtoo low – use a travel gas with21 percent or more oxygen 21 percent or more oxygen continued…continued…



The need for travel gasThe need for travel gas• If you experience any CNS oxygen toxicity If you experience any CNS oxygen toxicity

symptoms switch to a low oxygen gas to lower symptoms switch to a low oxygen gas to lower your PO2your PO2

Use caution with a hypoxic trimixUse caution with a hypoxic trimix Most likely to experience CNS oxygen toxicity at Most likely to experience CNS oxygen toxicity at

shallow depthsshallow depths Hypoxic trimix back gas may not have enough Hypoxic trimix back gas may not have enough

oxygen if you’re too shallow, switch to youroxygen if you’re too shallow, switch to yourtravel gas travel gas continued…continued…

The need for travel gasThe need for travel gas• If you experience any CNS oxygen toxicity If you experience any CNS oxygen toxicity

symptoms switch to a low oxygen gas to lower symptoms switch to a low oxygen gas to lower your PO2your PO2

Use caution with a hypoxic trimixUse caution with a hypoxic trimix Most likely to experience CNS oxygen toxicity at Most likely to experience CNS oxygen toxicity at

shallow depthsshallow depths Hypoxic trimix back gas may not have enough Hypoxic trimix back gas may not have enough

oxygen if you’re too shallow, switch to youroxygen if you’re too shallow, switch to yourtravel gas travel gas continued…continued…



The need for travel gasThe need for travel gas• Stay within the depth limits of the courseStay within the depth limits of the course

(75 metres/245 feet) and you’ll seldom if(75 metres/245 feet) and you’ll seldom ifever need less than 16 percent oxygen inever need less than 16 percent oxygen inyour back gasyour back gas

The need for travel gasThe need for travel gas• Stay within the depth limits of the courseStay within the depth limits of the course

(75 metres/245 feet) and you’ll seldom if(75 metres/245 feet) and you’ll seldom ifever need less than 16 percent oxygen inever need less than 16 percent oxygen inyour back gasyour back gas


Repetitive DivesRepetitive DivesRepetitive DivesRepetitive Dives

What is the recommendation regarding What is the recommendation regarding using air or enriched air for a repetitive using air or enriched air for a repetitive dive after a trimix dive?dive after a trimix dive?• Make repetitive dives to the same orMake repetitive dives to the same or

shallower depthshallower depth Oxygen content can be the same or higherOxygen content can be the same or higher Helium content should be appropriate for the depthHelium content should be appropriate for the depth

What is the recommendation regarding What is the recommendation regarding using air or enriched air for a repetitive using air or enriched air for a repetitive dive after a trimix dive?dive after a trimix dive?• Make repetitive dives to the same orMake repetitive dives to the same or

shallower depthshallower depth Oxygen content can be the same or higherOxygen content can be the same or higher Helium content should be appropriate for the depthHelium content should be appropriate for the depth


Repetitive DivesRepetitive DivesRepetitive DivesRepetitive Dives

More recommendationsMore recommendations• Not recommended to make a repetitive dive using Not recommended to make a repetitive dive using

enriched air as the bottom gasenriched air as the bottom gasafter a trimix diveafter a trimix dive

The concerns are theoreticalThe concerns are theoretical This is the conservative approachThis is the conservative approach

More recommendationsMore recommendations• Not recommended to make a repetitive dive using Not recommended to make a repetitive dive using

enriched air as the bottom gasenriched air as the bottom gasafter a trimix diveafter a trimix dive

The concerns are theoreticalThe concerns are theoretical This is the conservative approachThis is the conservative approach


Decompression IIDecompression IIDecompression IIDecompression II

Deep StopsDeep Stops Desktop Deco SoftwareDesktop Deco Software Multigas Trimix Dive ComputersMultigas Trimix Dive Computers General Rule on Deep StopsGeneral Rule on Deep Stops Air BreaksAir Breaks Deco GasesDeco Gases AscentsAscents

Deep StopsDeep Stops Desktop Deco SoftwareDesktop Deco Software Multigas Trimix Dive ComputersMultigas Trimix Dive Computers General Rule on Deep StopsGeneral Rule on Deep Stops Air BreaksAir Breaks Deco GasesDeco Gases AscentsAscents


Deep StopsDeep StopsDeep StopsDeep Stops

What is a deep stop?What is a deep stop?• Common practice in decompression divingCommon practice in decompression diving

Deep stops are stops one to five minutes between Deep stops are stops one to five minutes between the bottom and the first deco stopthe bottom and the first deco stop

Some desktop deco software can be set to enterSome desktop deco software can be set to enterdeep stopsdeep stops

• Field experience and theory support using Field experience and theory support using deep stops deep stops

Less fatigue after the diveLess fatigue after the dive Used widely, no indications of problemsUsed widely, no indications of problems Bubble dynamic models all predict aBubble dynamic models all predict a

benefit to making decompressionbenefit to making decompressionstops deeperstops deeper

What is a deep stop?What is a deep stop?• Common practice in decompression divingCommon practice in decompression diving

Deep stops are stops one to five minutes between Deep stops are stops one to five minutes between the bottom and the first deco stopthe bottom and the first deco stop

Some desktop deco software can be set to enterSome desktop deco software can be set to enterdeep stopsdeep stops

• Field experience and theory support using Field experience and theory support using deep stops deep stops

Less fatigue after the diveLess fatigue after the dive Used widely, no indications of problemsUsed widely, no indications of problems Bubble dynamic models all predict aBubble dynamic models all predict a



Deep StopsDeep StopsDeep StopsDeep Stops

What information supports the use of deep What information supports the use of deep stops in trimix diving?stops in trimix diving?• Field experience and theory support using Field experience and theory support using

deep stops deep stops Less fatigue after the diveLess fatigue after the dive Used widely, no indications of problemsUsed widely, no indications of problems Bubble dynamic models all predict aBubble dynamic models all predict a


What information supports the use of deep What information supports the use of deep stops in trimix diving?stops in trimix diving?• Field experience and theory support using Field experience and theory support using

deep stops deep stops Less fatigue after the diveLess fatigue after the dive Used widely, no indications of problemsUsed widely, no indications of problems Bubble dynamic models all predict aBubble dynamic models all predict a



Desktop Deco SoftwareDesktop Deco SoftwareDesktop Deco SoftwareDesktop Deco Software

What are three ways that you determine What are three ways that you determine deep stops using desktop deco software?deep stops using desktop deco software?• Desktop deco software can calculate deep Desktop deco software can calculate deep

stops three waysstops three ways Automatic deep stopsAutomatic deep stops

• Set the software to generate themSet the software to generate them Use a bubble dynamics modelUse a bubble dynamics model

• Neo-Haldanean modelNeo-Haldanean model• Buhlmann model Buhlmann model

Determine deep stops and insert themDetermine deep stops and insert themas waypointsas waypoints

• Common to use multiple deep stopsCommon to use multiple deep stopscontinued…continued…

What are three ways that you determine What are three ways that you determine deep stops using desktop deco software?deep stops using desktop deco software?• Desktop deco software can calculate deep Desktop deco software can calculate deep

stops three waysstops three ways Automatic deep stopsAutomatic deep stops

• Set the software to generate themSet the software to generate them Use a bubble dynamics modelUse a bubble dynamics model

• Neo-Haldanean modelNeo-Haldanean model• Buhlmann model Buhlmann model

Determine deep stops and insert themDetermine deep stops and insert themas waypointsas waypoints

• Common to use multiple deep stopsCommon to use multiple deep stopscontinued…continued…


Determining Deep StopsDetermining Deep StopsDetermining Deep StopsDetermining Deep Stops

To determine the deep stops:To determine the deep stops:• First deep stop is the approximate halfway First deep stop is the approximate halfway

point between bottom and first required stoppoint between bottom and first required stop• Each successive deep stop is next halfway Each successive deep stop is next halfway

point between current deep stop and first point between current deep stop and first required stop, until reaching a stop 3 required stop, until reaching a stop 3 metres/10 feet deeper than first required stopmetres/10 feet deeper than first required stop

Enter into deco softwareEnter into deco software Typically one to five minutes,Typically one to five minutes,

one-two minutes most common one-two minutes most common continued…continued…

To determine the deep stops:To determine the deep stops:• First deep stop is the approximate halfway First deep stop is the approximate halfway

point between bottom and first required stoppoint between bottom and first required stop• Each successive deep stop is next halfway Each successive deep stop is next halfway

point between current deep stop and first point between current deep stop and first required stop, until reaching a stop 3 required stop, until reaching a stop 3 metres/10 feet deeper than first required stopmetres/10 feet deeper than first required stop

Enter into deco softwareEnter into deco software Typically one to five minutes,Typically one to five minutes,

one-two minutes most common one-two minutes most common continued…continued…


Calculating Deep StopsCalculating Deep StopsCalculating Deep StopsCalculating Deep Stops

To calculate the deep stop depth:To calculate the deep stop depth:• Subtract the first required stop depth from the Subtract the first required stop depth from the

bottom or previous stop depthbottom or previous stop depth Divide this by two and subtract from the bottom or Divide this by two and subtract from the bottom or

previous stop depthprevious stop depth Typical to round to the next deeper stop in 3 Typical to round to the next deeper stop in 3

metres/10 foot incrementsmetres/10 foot increments Can use Deep Stop Calculation TableCan use Deep Stop Calculation Table

To calculate the deep stop depth:To calculate the deep stop depth:• Subtract the first required stop depth from the Subtract the first required stop depth from the

bottom or previous stop depthbottom or previous stop depth Divide this by two and subtract from the bottom or Divide this by two and subtract from the bottom or

previous stop depthprevious stop depth Typical to round to the next deeper stop in 3 Typical to round to the next deeper stop in 3

metres/10 foot incrementsmetres/10 foot increments Can use Deep Stop Calculation TableCan use Deep Stop Calculation Table

MetricExample

ImperialExample

Next


Deep Stop Calculation Table - MetricDeep Stop Calculation Table - MetricDeep Stop Calculation Table - MetricDeep Stop Calculation Table - Metric

Example: You’re ascending from 60 metres. Your Example: You’re ascending from 60 metres. Your first stop is at 9 metres. What are your deep first stop is at 9 metres. What are your deep stops?stops? • First deep stop is approximately 35 metres (midpoint First deep stop is approximately 35 metres (midpoint

between 60 metres and 9 metres)between 60 metres and 9 metres)• Second deep stop is 23 metres (midpoint from 35 Second deep stop is 23 metres (midpoint from 35

metres, rounded to 36 metres, and 9 metres)metres, rounded to 36 metres, and 9 metres)• Third deep stop is 17 metres (rounded to 18 metres)Third deep stop is 17 metres (rounded to 18 metres)• Fourth deep stop is 14 metres (rounded to 15 metres)Fourth deep stop is 14 metres (rounded to 15 metres)

Example: You’re ascending from 60 metres. Your Example: You’re ascending from 60 metres. Your first stop is at 9 metres. What are your deep first stop is at 9 metres. What are your deep stops?stops? • First deep stop is approximately 35 metres (midpoint First deep stop is approximately 35 metres (midpoint

between 60 metres and 9 metres)between 60 metres and 9 metres)• Second deep stop is 23 metres (midpoint from 35 Second deep stop is 23 metres (midpoint from 35

metres, rounded to 36 metres, and 9 metres)metres, rounded to 36 metres, and 9 metres)• Third deep stop is 17 metres (rounded to 18 metres)Third deep stop is 17 metres (rounded to 18 metres)• Fourth deep stop is 14 metres (rounded to 15 metres)Fourth deep stop is 14 metres (rounded to 15 metres)

Imperial Example

Next


Deep Stop Calculation Table - ImperialDeep Stop Calculation Table - ImperialDeep Stop Calculation Table - ImperialDeep Stop Calculation Table - Imperial

Example: You’re ascending from 200 feet.Example: You’re ascending from 200 feet.Your first stop is at 30 feet. What are yourYour first stop is at 30 feet. What are yourdeep stops?deep stops? • First deep stop is approximately 115 feet (midpoint First deep stop is approximately 115 feet (midpoint

between 200 feet and 30 feet)between 200 feet and 30 feet)• Second deep stop is 75 feet (midpoint from 115 feet, Second deep stop is 75 feet (midpoint from 115 feet,

rounded to 120 feet, and 30 feet)rounded to 120 feet, and 30 feet)• Third deep stop is 55 feet (rounded to 60 feet)Third deep stop is 55 feet (rounded to 60 feet)• Fourth deep stop is 45 feet (rounded to 50 feet)Fourth deep stop is 45 feet (rounded to 50 feet)

Example: You’re ascending from 200 feet.Example: You’re ascending from 200 feet.Your first stop is at 30 feet. What are yourYour first stop is at 30 feet. What are yourdeep stops?deep stops? • First deep stop is approximately 115 feet (midpoint First deep stop is approximately 115 feet (midpoint

between 200 feet and 30 feet)between 200 feet and 30 feet)• Second deep stop is 75 feet (midpoint from 115 feet, Second deep stop is 75 feet (midpoint from 115 feet,

rounded to 120 feet, and 30 feet)rounded to 120 feet, and 30 feet)• Third deep stop is 55 feet (rounded to 60 feet)Third deep stop is 55 feet (rounded to 60 feet)• Fourth deep stop is 45 feet (rounded to 50 feet)Fourth deep stop is 45 feet (rounded to 50 feet)

MetricExample

Previous


Multigas Trimix Dive ComputersMultigas Trimix Dive ComputersMultigas Trimix Dive ComputersMultigas Trimix Dive Computers

What are two ways to determine deep stops What are two ways to determine deep stops using a multigas trimix dive computer that using a multigas trimix dive computer that does not calculate deep stops?does not calculate deep stops?• If multigas computer doesn’t provide deep stops If multigas computer doesn’t provide deep stops

you may have to determine deep stops onyou may have to determine deep stops onthe flythe fly

Calculate in your head (not recommended)Calculate in your head (not recommended) Use Deep Stops Calculation Table slate and the first Use Deep Stops Calculation Table slate and the first

required stop shown on computerrequired stop shown on computer• Round to the next deeper 3 metre/10 footRound to the next deeper 3 metre/10 foot

increment stop depth on tableincrement stop depth on table• Dive computer automatically calculatesDive computer automatically calculates

your deep stops into decompressionyour deep stops into decompressionrequirementsrequirements

What are two ways to determine deep stops What are two ways to determine deep stops using a multigas trimix dive computer that using a multigas trimix dive computer that does not calculate deep stops?does not calculate deep stops?• If multigas computer doesn’t provide deep stops If multigas computer doesn’t provide deep stops

you may have to determine deep stops onyou may have to determine deep stops onthe flythe fly

Calculate in your head (not recommended)Calculate in your head (not recommended) Use Deep Stops Calculation Table slate and the first Use Deep Stops Calculation Table slate and the first

required stop shown on computerrequired stop shown on computer• Round to the next deeper 3 metre/10 footRound to the next deeper 3 metre/10 foot

increment stop depth on tableincrement stop depth on table• Dive computer automatically calculatesDive computer automatically calculates

your deep stops into decompressionyour deep stops into decompressionrequirementsrequirements

Previous


General Rule on Deep StopsGeneral Rule on Deep StopsGeneral Rule on Deep StopsGeneral Rule on Deep Stops

As a general rule, what gas should you use As a general rule, what gas should you use at your deep stop and why?at your deep stop and why?• You generally make your deep stops using back You generally make your deep stops using back

gas (lowest oxygen gas)gas (lowest oxygen gas) This reduces PO2 to nearly 1.4 on the bottomThis reduces PO2 to nearly 1.4 on the bottom First stop after gas switch often puts your PO2 up to First stop after gas switch often puts your PO2 up to

1.6, wise to keep oxygen exposure lower as long as 1.6, wise to keep oxygen exposure lower as long as possible possible continued…continued…

As a general rule, what gas should you use As a general rule, what gas should you use at your deep stop and why?at your deep stop and why?• You generally make your deep stops using back You generally make your deep stops using back

gas (lowest oxygen gas)gas (lowest oxygen gas) This reduces PO2 to nearly 1.4 on the bottomThis reduces PO2 to nearly 1.4 on the bottom First stop after gas switch often puts your PO2 up to First stop after gas switch often puts your PO2 up to

1.6, wise to keep oxygen exposure lower as long as 1.6, wise to keep oxygen exposure lower as long as possible possible continued…continued…


More on Deep StopsMore on Deep StopsMore on Deep StopsMore on Deep Stops

What gas to use?What gas to use?• On some dives, deep stops may be deep On some dives, deep stops may be deep

enough to stay on trimix to manage narcosisenough to stay on trimix to manage narcosis• Recommended to stay on lowerRecommended to stay on lower

oxygen back gas until reaching a deep stop oxygen back gas until reaching a deep stop shallow enough for the travel gas PO2 to be shallow enough for the travel gas PO2 to be less than 1.4 ata or lowerless than 1.4 ata or lower

• May be possible to plan deep stop asMay be possible to plan deep stop asextended second level ofextended second level ofmultilevel profilemultilevel profile

What gas to use?What gas to use?• On some dives, deep stops may be deep On some dives, deep stops may be deep

enough to stay on trimix to manage narcosisenough to stay on trimix to manage narcosis• Recommended to stay on lowerRecommended to stay on lower

oxygen back gas until reaching a deep stop oxygen back gas until reaching a deep stop shallow enough for the travel gas PO2 to be shallow enough for the travel gas PO2 to be less than 1.4 ata or lowerless than 1.4 ata or lower

• May be possible to plan deep stop asMay be possible to plan deep stop asextended second level ofextended second level ofmultilevel profilemultilevel profile


Air BreaksAir BreaksAir BreaksAir Breaks

What are air breaks? What are air breaks? • An air break is a break from high oxygen deco An air break is a break from high oxygen deco

gas to air (or lowest oxygen gas available) for gas to air (or lowest oxygen gas available) for five minutes each 20 to 25 minutes maximumfive minutes each 20 to 25 minutes maximum

Reduces risk of CNS toxicityReduces risk of CNS toxicity Does not count as deco timeDoes not count as deco time Switch multigas gas computers to the break gasSwitch multigas gas computers to the break gas Some desktop deco software automaticallySome desktop deco software automatically

add air breaksadd air breaks Air breaks more frequent are fineAir breaks more frequent are fine 20 to 25 minutes is the maximum20 to 25 minutes is the maximum

without a break, more is better without a break, more is better continued…continued…

What are air breaks? What are air breaks? • An air break is a break from high oxygen deco An air break is a break from high oxygen deco

gas to air (or lowest oxygen gas available) for gas to air (or lowest oxygen gas available) for five minutes each 20 to 25 minutes maximumfive minutes each 20 to 25 minutes maximum

Reduces risk of CNS toxicityReduces risk of CNS toxicity Does not count as deco timeDoes not count as deco time Switch multigas gas computers to the break gasSwitch multigas gas computers to the break gas Some desktop deco software automaticallySome desktop deco software automatically

add air breaksadd air breaks Air breaks more frequent are fineAir breaks more frequent are fine 20 to 25 minutes is the maximum20 to 25 minutes is the maximum

without a break, more is better without a break, more is better continued…continued…


Air BreaksAir BreaksAir BreaksAir Breaks

Why and how should you do them?Why and how should you do them?• Total oxygen exposure typically higher on Total oxygen exposure typically higher on

trimix, air breaks even more importanttrimix, air breaks even more important• The lowest oxygen deco gas without helium or The lowest oxygen deco gas without helium or

with very low helium is best choicewith very low helium is best choice• Don’t count as deco time unless entered with Don’t count as deco time unless entered with

the appropriate gas into deco softwarethe appropriate gas into deco software• Count as deco time with multigasCount as deco time with multigas

trimix computerstrimix computers

Why and how should you do them?Why and how should you do them?• Total oxygen exposure typically higher on Total oxygen exposure typically higher on

trimix, air breaks even more importanttrimix, air breaks even more important• The lowest oxygen deco gas without helium or The lowest oxygen deco gas without helium or

with very low helium is best choicewith very low helium is best choice• Don’t count as deco time unless entered with Don’t count as deco time unless entered with

the appropriate gas into deco softwarethe appropriate gas into deco software• Count as deco time with multigasCount as deco time with multigas

trimix computerstrimix computers


Deco GasesDeco GasesDeco GasesDeco Gases

What are the most common decompression gases What are the most common decompression gases for trimix diving?for trimix diving?• Trimix diving requires accelerated decompressionTrimix diving requires accelerated decompression• Practice is to NO TOX switch to higher oxygen, lower Practice is to NO TOX switch to higher oxygen, lower

helium gases to speed elimination of helium and helium gases to speed elimination of helium and nitrogennitrogen

• Most common gassesMost common gasses 100 percent oxygen from 6 metres/20 feet to the surface100 percent oxygen from 6 metres/20 feet to the surface EANx50 from 21 metres/70 feetEANx50 from 21 metres/70 feet EANx36 from 33 metres/110 feetEANx36 from 33 metres/110 feet Other variations of EANx mayOther variations of EANx may

be necessary be necessary continued…continued…

What are the most common decompression gases What are the most common decompression gases for trimix diving?for trimix diving?• Trimix diving requires accelerated decompressionTrimix diving requires accelerated decompression• Practice is to NO TOX switch to higher oxygen, lower Practice is to NO TOX switch to higher oxygen, lower

helium gases to speed elimination of helium and helium gases to speed elimination of helium and nitrogennitrogen

• Most common gassesMost common gasses 100 percent oxygen from 6 metres/20 feet to the surface100 percent oxygen from 6 metres/20 feet to the surface EANx50 from 21 metres/70 feetEANx50 from 21 metres/70 feet EANx36 from 33 metres/110 feetEANx36 from 33 metres/110 feet Other variations of EANx mayOther variations of EANx may

be necessary be necessary continued…continued…


Deco GasesDeco GasesDeco GasesDeco Gases

Why is there some theoretical benefit to having a Why is there some theoretical benefit to having a small percentage of helium in some of your deco small percentage of helium in some of your deco gases?gases?• Growing trend to use five to 20 percent helium in the Growing trend to use five to 20 percent helium in the

deco gasesdeco gases Helium in gas important on extreme divesHelium in gas important on extreme dives Isobaric counterdiffusion not substantial issueIsobaric counterdiffusion not substantial issue Benefits largely theoreticalBenefits largely theoretical Helium in deco gases raise dive costs Helium in deco gases raise dive costs Keep helium in decompression by usingKeep helium in decompression by using

deco for stops shallower than youdeco for stops shallower than youotherwise mightotherwise might

• Important to balance the advantages andImportant to balance the advantages anddisadvantages of different deco gas choicesdisadvantages of different deco gas choices

Why is there some theoretical benefit to having a Why is there some theoretical benefit to having a small percentage of helium in some of your deco small percentage of helium in some of your deco gases?gases?• Growing trend to use five to 20 percent helium in the Growing trend to use five to 20 percent helium in the

deco gasesdeco gases Helium in gas important on extreme divesHelium in gas important on extreme dives Isobaric counterdiffusion not substantial issueIsobaric counterdiffusion not substantial issue Benefits largely theoreticalBenefits largely theoretical Helium in deco gases raise dive costs Helium in deco gases raise dive costs Keep helium in decompression by usingKeep helium in decompression by using

deco for stops shallower than youdeco for stops shallower than youotherwise mightotherwise might

• Important to balance the advantages andImportant to balance the advantages anddisadvantages of different deco gas choicesdisadvantages of different deco gas choices


AscentsAscentsAscentsAscents

What is the optimum way to ascend What is the optimum way to ascend when making a trimix decompression when making a trimix decompression dive?dive?• Ascents should be gradual, controlled and Ascents should be gradual, controlled and

not faster than 10 mpm/30 fpmnot faster than 10 mpm/30 fpm• Use gauges to assist ascentUse gauges to assist ascent• Stop at each 3 metres/10 feet for controlStop at each 3 metres/10 feet for control• Make deep stops a habitualMake deep stops a habitual

part of ascentspart of ascents

What is the optimum way to ascend What is the optimum way to ascend when making a trimix decompression when making a trimix decompression dive?dive?• Ascents should be gradual, controlled and Ascents should be gradual, controlled and

not faster than 10 mpm/30 fpmnot faster than 10 mpm/30 fpm• Use gauges to assist ascentUse gauges to assist ascent• Stop at each 3 metres/10 feet for controlStop at each 3 metres/10 feet for control• Make deep stops a habitualMake deep stops a habitual

part of ascentspart of ascents


AscentsAscentsAscentsAscents

Optimum way to Optimum way to ascendascend• Better not to skip stops even Better not to skip stops even

if multigas gas if multigas gas computer/desktop deco computer/desktop deco table allows ittable allows it

• Last part of ascent biggest Last part of ascent biggest gas volume changegas volume change

• Team work and Team work and communicationcommunicationessentialessential

Optimum way to Optimum way to ascendascend• Better not to skip stops even Better not to skip stops even

if multigas gas if multigas gas computer/desktop deco computer/desktop deco table allows ittable allows it

• Last part of ascent biggest Last part of ascent biggest gas volume changegas volume change

• Team work and Team work and communicationcommunicationessentialessential


Techniques & Procedures IITechniques & Procedures IITechniques & Procedures IITechniques & Procedures II

Wearing Travel GasWearing Travel Gas Using Travel GasUsing Travel Gas

Wearing Travel GasWearing Travel Gas Using Travel GasUsing Travel Gas


Wearing Travel GasWearing Travel GasWearing Travel GasWearing Travel Gas

Where do you wear travel gas whenWhere do you wear travel gas whenusing it?using it?• When using travel gas follow these proceduresWhen using travel gas follow these procedures

To avoid using back gas during ascent and blacking To avoid using back gas during ascent and blacking out from hypoxia out from hypoxia

To avoid failing to switch to back gas at depth and To avoid failing to switch to back gas at depth and risking CNS oxygen toxicityrisking CNS oxygen toxicity

• Whether stage deco cylinders are all left or Whether stage deco cylinders are all left or right/left, travel gas is normallyright/left, travel gas is normallyupper left cylinder, the lowestupper left cylinder, the lowestoxygen gasoxygen gas

Where do you wear travel gas whenWhere do you wear travel gas whenusing it?using it?• When using travel gas follow these proceduresWhen using travel gas follow these procedures

To avoid using back gas during ascent and blacking To avoid using back gas during ascent and blacking out from hypoxia out from hypoxia

To avoid failing to switch to back gas at depth and To avoid failing to switch to back gas at depth and risking CNS oxygen toxicityrisking CNS oxygen toxicity

• Whether stage deco cylinders are all left or Whether stage deco cylinders are all left or right/left, travel gas is normallyright/left, travel gas is normallyupper left cylinder, the lowestupper left cylinder, the lowestoxygen gasoxygen gas


Using Travel GasUsing Travel GasUsing Travel GasUsing Travel Gas

What is the procedure for beginning a dive What is the procedure for beginning a dive on travel gas?on travel gas?• Begin dive by confirming the team is breathing Begin dive by confirming the team is breathing

correct travel gascorrect travel gas With hypoxic bottom mix, clip primary second stage With hypoxic bottom mix, clip primary second stage

to prevent using it at start of diveto prevent using it at start of dive May enter water with travel gas already secured to May enter water with travel gas already secured to

use, if in rough conditionsuse, if in rough conditions

• After confirmation everyone’sAfter confirmation everyone’sbreathing travel gas, the dive beginsbreathing travel gas, the dive beginscontinue…continue…

What is the procedure for beginning a dive What is the procedure for beginning a dive on travel gas?on travel gas?• Begin dive by confirming the team is breathing Begin dive by confirming the team is breathing

correct travel gascorrect travel gas With hypoxic bottom mix, clip primary second stage With hypoxic bottom mix, clip primary second stage

to prevent using it at start of diveto prevent using it at start of dive May enter water with travel gas already secured to May enter water with travel gas already secured to

use, if in rough conditionsuse, if in rough conditions

• After confirmation everyone’sAfter confirmation everyone’sbreathing travel gas, the dive beginsbreathing travel gas, the dive beginscontinue…continue…


Using Travel GasUsing Travel GasUsing Travel GasUsing Travel Gas

The dive beginsThe dive begins• At depth team switches to back gas together at At depth team switches to back gas together at

predetermined depthpredetermined depth• If travel gas is used for decompression treat as If travel gas is used for decompression treat as

any other deco gas – NO TOX switchesany other deco gas – NO TOX switches• If isobaric counterdiffusion or ascending above If isobaric counterdiffusion or ascending above

a hypoxic trimix’s usable depth are possible a hypoxic trimix’s usable depth are possible issues, go to travel gasissues, go to travel gasinstead of back gas betweeninstead of back gas betweencylinders when NO TOX switchingcylinders when NO TOX switching

The dive beginsThe dive begins• At depth team switches to back gas together at At depth team switches to back gas together at

predetermined depthpredetermined depth• If travel gas is used for decompression treat as If travel gas is used for decompression treat as

any other deco gas – NO TOX switchesany other deco gas – NO TOX switches• If isobaric counterdiffusion or ascending above If isobaric counterdiffusion or ascending above

a hypoxic trimix’s usable depth are possible a hypoxic trimix’s usable depth are possible issues, go to travel gasissues, go to travel gasinstead of back gas betweeninstead of back gas betweencylinders when NO TOX switchingcylinders when NO TOX switching


Emergency Procedures IIEmergency Procedures IIEmergency Procedures IIEmergency Procedures II

Loss of Loss of Decompression Decompression Gases Gases

Multigas Trimix Multigas Trimix Computer FailureComputer Failure

Loss of Loss of Decompression Decompression Gases Gases

Multigas Trimix Multigas Trimix Computer FailureComputer Failure


Loss of Decompression GasesLoss of Decompression GasesLoss of Decompression GasesLoss of Decompression Gases

What are your options if you lose your What are your options if you lose your decompression gasses on a trimix dive?decompression gasses on a trimix dive?• Loss of decompression gases limits your options and Loss of decompression gases limits your options and

emphasis must be on preventionemphasis must be on prevention Never stage deco cylinders if you doubt you can relocate themNever stage deco cylinders if you doubt you can relocate them Don’t rely on gases supplied by a dive boatDon’t rely on gases supplied by a dive boat

• If you lose your deco gases the best option is to have If you lose your deco gases the best option is to have support divers bring down the gases you needsupport divers bring down the gases you need

If no support divers deco with your teammate’s reservesIf no support divers deco with your teammate’s reserves Last resort deco as long as possible withLast resort deco as long as possible with

your back gasyour back gas

• Emphasis on prevention – wear decoEmphasis on prevention – wear decocylinders for entire divecylinders for entire dive

What are your options if you lose your What are your options if you lose your decompression gasses on a trimix dive?decompression gasses on a trimix dive?• Loss of decompression gases limits your options and Loss of decompression gases limits your options and

emphasis must be on preventionemphasis must be on prevention Never stage deco cylinders if you doubt you can relocate themNever stage deco cylinders if you doubt you can relocate them Don’t rely on gases supplied by a dive boatDon’t rely on gases supplied by a dive boat

• If you lose your deco gases the best option is to have If you lose your deco gases the best option is to have support divers bring down the gases you needsupport divers bring down the gases you need

If no support divers deco with your teammate’s reservesIf no support divers deco with your teammate’s reserves Last resort deco as long as possible withLast resort deco as long as possible with

your back gasyour back gas

• Emphasis on prevention – wear decoEmphasis on prevention – wear decocylinders for entire divecylinders for entire dive


Multigas Trimix Computer FailureMultigas Trimix Computer FailureMultigas Trimix Computer FailureMultigas Trimix Computer Failure

How do you handle a failure of your multigas How do you handle a failure of your multigas trimix computer during a dive?trimix computer during a dive?• If your multigas trimix computer fails use your backup If your multigas trimix computer fails use your backup

multigas trimix computermultigas trimix computer• No backup computer, use your backup tables with depth No backup computer, use your backup tables with depth

gauge and bottom timergauge and bottom timer• Use the following steps to enter your backup tablesUse the following steps to enter your backup tables

Find the contingency table for the time and maximum Find the contingency table for the time and maximum depth of your divedepth of your dive

Find the decompression stop depth at which your computer Find the decompression stop depth at which your computer failed, complete the time indicatedfailed, complete the time indicatedby the tableby the table

Finish your decompression following theFinish your decompression following thetable’s stop timestable’s stop times

How do you handle a failure of your multigas How do you handle a failure of your multigas trimix computer during a dive?trimix computer during a dive?• If your multigas trimix computer fails use your backup If your multigas trimix computer fails use your backup

multigas trimix computermultigas trimix computer• No backup computer, use your backup tables with depth No backup computer, use your backup tables with depth

gauge and bottom timergauge and bottom timer• Use the following steps to enter your backup tablesUse the following steps to enter your backup tables

Find the contingency table for the time and maximum Find the contingency table for the time and maximum depth of your divedepth of your dive

Find the decompression stop depth at which your computer Find the decompression stop depth at which your computer failed, complete the time indicatedfailed, complete the time indicatedby the tableby the table

Finish your decompression following theFinish your decompression following thetable’s stop timestable’s stop times


Team Diving IITeam Diving IITeam Diving IITeam Diving II

Roles and Roles and Benefits of a Benefits of a Support DiverSupport Diver

Characteristics Characteristics of a Support of a Support DiverDiver

Roles and Roles and Benefits of a Benefits of a Support DiverSupport Diver

Characteristics Characteristics of a Support of a Support DiverDiver


Roles and Benefits of a Support DiverRoles and Benefits of a Support DiverRoles and Benefits of a Support DiverRoles and Benefits of a Support Diver

What are the roles of a support diver and What are the roles of a support diver and why are support divers especially why are support divers especially beneficial on a trimix dive ?beneficial on a trimix dive ?• Support divers check on divers to make sure Support divers check on divers to make sure

they have ample gasthey have ample gas Especially beneficial as inadequate deco gas likely Especially beneficial as inadequate deco gas likely

means insufficient gas to decompress adequatelymeans insufficient gas to decompress adequately

• Support divers shuttling gear Support divers shuttling gear Trimix dives employ more cylindersTrimix dives employ more cylinders

• Support divers watch for and locateSupport divers watch for and locateseparated divers separated divers continued…continued…

What are the roles of a support diver and What are the roles of a support diver and why are support divers especially why are support divers especially beneficial on a trimix dive ?beneficial on a trimix dive ?• Support divers check on divers to make sure Support divers check on divers to make sure

they have ample gasthey have ample gas Especially beneficial as inadequate deco gas likely Especially beneficial as inadequate deco gas likely

means insufficient gas to decompress adequatelymeans insufficient gas to decompress adequately

• Support divers shuttling gear Support divers shuttling gear Trimix dives employ more cylindersTrimix dives employ more cylinders

• Support divers watch for and locateSupport divers watch for and locateseparated divers separated divers continued…continued…


Roles and Benefits of a Support DiverRoles and Benefits of a Support DiverRoles and Benefits of a Support DiverRoles and Benefits of a Support Diver

More roles and benefits of support diversMore roles and benefits of support divers• Support divers hover near decoing diversSupport divers hover near decoing divers

Confirming gas switches, tables and runtimesConfirming gas switches, tables and runtimes

• Support divers sit standby on the boat or shore Support divers sit standby on the boat or shore ready to assist in an emergencyready to assist in an emergency

Need to be qualified and equipped for deep divesNeed to be qualified and equipped for deep dives

• Support divers shuttle communications Support divers shuttle communications between the divers and surface supportbetween the divers and surface support

More roles and benefits of support diversMore roles and benefits of support divers• Support divers hover near decoing diversSupport divers hover near decoing divers

Confirming gas switches, tables and runtimesConfirming gas switches, tables and runtimes

• Support divers sit standby on the boat or shore Support divers sit standby on the boat or shore ready to assist in an emergencyready to assist in an emergency

Need to be qualified and equipped for deep divesNeed to be qualified and equipped for deep dives

• Support divers shuttle communications Support divers shuttle communications between the divers and surface supportbetween the divers and surface support


Characteristics of a Support DiverCharacteristics of a Support DiverCharacteristics of a Support DiverCharacteristics of a Support Diver

What characteristics does an effective What characteristics does an effective support diver have?support diver have?• Qualified for support dive and depthsQualified for support dive and depths

Complex missions require greater qualificationsComplex missions require greater qualifications

• Good communicatorGood communicator• Creative problem solverCreative problem solver

Able to take care of what a diver needsAble to take care of what a diver needs

What characteristics does an effective What characteristics does an effective support diver have?support diver have?• Qualified for support dive and depthsQualified for support dive and depths

Complex missions require greater qualificationsComplex missions require greater qualifications

• Good communicatorGood communicator• Creative problem solverCreative problem solver

Able to take care of what a diver needsAble to take care of what a diver needs


Characteristics of a Support DiverCharacteristics of a Support DiverCharacteristics of a Support DiverCharacteristics of a Support Diver

More characteristicsMore characteristics• PatientPatient

Able to hang out and watch divers decoAble to hang out and watch divers deco

• Stay out of decompression exceptStay out of decompression excepton highly complex dives where it’son highly complex dives where it’splanned forplanned for

Support divers may need set up diversSupport divers may need set up diversfor this reasonfor this reason

More characteristicsMore characteristics• PatientPatient

Able to hang out and watch divers decoAble to hang out and watch divers deco

• Stay out of decompression exceptStay out of decompression excepton highly complex dives where it’son highly complex dives where it’splanned forplanned for

Support divers may need set up diversSupport divers may need set up diversfor this reasonfor this reason


Thinking Like a Trimix Diver IIThinking Like a Trimix Diver IIThinking Like a Trimix Diver IIThinking Like a Trimix Diver II

Becoming a Trimix Diver Sets You ApartBecoming a Trimix Diver Sets You Apart Distinction comes with ResponsibilitiesDistinction comes with Responsibilities

Becoming a Trimix Diver Sets You ApartBecoming a Trimix Diver Sets You Apart Distinction comes with ResponsibilitiesDistinction comes with Responsibilities


Becoming a Trimix Diver Sets You ApartBecoming a Trimix Diver Sets You ApartBecoming a Trimix Diver Sets You ApartBecoming a Trimix Diver Sets You Apart

Why does becoming a trimix diver put you Why does becoming a trimix diver put you in a position of distinction in the dive in a position of distinction in the dive community?community?• You will be “at the bottom of the top”You will be “at the bottom of the top”

You will be part of less than 1 percent of divers You will be part of less than 1 percent of divers qualified to dive in the sport’s deepest rangesqualified to dive in the sport’s deepest ranges

You will be among those who accept the sport’s You will be among those who accept the sport’s greatest potential risksgreatest potential risks

Your level of expertise with respectYour level of expertise with respectto dive skill and knowledge will beto dive skill and knowledge will beexpected to be almost professionalexpected to be almost professional

Why does becoming a trimix diver put you Why does becoming a trimix diver put you in a position of distinction in the dive in a position of distinction in the dive community?community?• You will be “at the bottom of the top”You will be “at the bottom of the top”

You will be part of less than 1 percent of divers You will be part of less than 1 percent of divers qualified to dive in the sport’s deepest rangesqualified to dive in the sport’s deepest ranges

You will be among those who accept the sport’s You will be among those who accept the sport’s greatest potential risksgreatest potential risks

Your level of expertise with respectYour level of expertise with respectto dive skill and knowledge will beto dive skill and knowledge will beexpected to be almost professionalexpected to be almost professional


Distinction comes with ResponsibilitiesDistinction comes with ResponsibilitiesDistinction comes with ResponsibilitiesDistinction comes with Responsibilities

What four responsibilities do you have in What four responsibilities do you have in that role?that role?• Be a role modelBe a role model

Respect and follow all the rules and procedures Respect and follow all the rules and procedures

• Show humilityShow humility Diving is diverse, broad and evolving discipline – Diving is diverse, broad and evolving discipline –

no one knows everything about itno one knows everything about it Keep an open mind to learn more Keep an open mind to learn more continued…continued…

What four responsibilities do you have in What four responsibilities do you have in that role?that role?• Be a role modelBe a role model

Respect and follow all the rules and procedures Respect and follow all the rules and procedures

• Show humilityShow humility Diving is diverse, broad and evolving discipline – Diving is diverse, broad and evolving discipline –

no one knows everything about itno one knows everything about it Keep an open mind to learn more Keep an open mind to learn more continued…continued…


Distinction comes with ResponsibilitiesDistinction comes with ResponsibilitiesDistinction comes with ResponsibilitiesDistinction comes with Responsibilities

Two more Two more responsibilitiesresponsibilities• Bring up less Bring up less

experienced tec diversexperienced tec divers Pass your experience on to Pass your experience on to

less experiencedless experienced

• Staying currentStaying current Keep informed, dive Keep informed, dive

frequently and develop a frequently and develop a reference libraryreference library

Two more Two more responsibilitiesresponsibilities• Bring up less Bring up less

experienced tec diversexperienced tec divers Pass your experience on to Pass your experience on to

less experiencedless experienced

• Staying currentStaying current Keep informed, dive Keep informed, dive

frequently and develop a frequently and develop a reference libraryreference library


Practical Application Two - Practical Application Two - ObjectivesObjectivesPractical Application Two - Practical Application Two - ObjectivesObjectives

Demonstrate the use of oxygen and (if available) Demonstrate the use of oxygen and (if available) helium analyzers to determine the contents of helium analyzers to determine the contents of trimix blendstrimix blends

Working as a team and using desktop deco Working as a team and using desktop deco softwaresoftware• Plan two trimix dives, both with deep stopsPlan two trimix dives, both with deep stops

First dive requiring a travel gas and three deco gassesFirst dive requiring a travel gas and three deco gasses Second dive requiring three or four deco gases but no Second dive requiring three or four deco gases but no

travel gastravel gas

• Plans to include gas consumption, oxygenPlans to include gas consumption, oxygenexposure, decompression schedules, turnexposure, decompression schedules, turnpressures and contingency decompressionpressures and contingency decompressionschedules for each team memberschedules for each team member

Demonstrate the use of oxygen and (if available) Demonstrate the use of oxygen and (if available) helium analyzers to determine the contents of helium analyzers to determine the contents of trimix blendstrimix blends

Working as a team and using desktop deco Working as a team and using desktop deco softwaresoftware• Plan two trimix dives, both with deep stopsPlan two trimix dives, both with deep stops

First dive requiring a travel gas and three deco gassesFirst dive requiring a travel gas and three deco gasses Second dive requiring three or four deco gases but no Second dive requiring three or four deco gases but no

travel gastravel gas

• Plans to include gas consumption, oxygenPlans to include gas consumption, oxygenexposure, decompression schedules, turnexposure, decompression schedules, turnpressures and contingency decompressionpressures and contingency decompressionschedules for each team memberschedules for each team member


Presentation Two ReviewPresentation Two ReviewPresentation Two ReviewPresentation Two Review




Let’s Go DivingLet’s Go DivingLet’s Go DivingLet’s Go Diving

Training Dive Two - Training Dive Two - ObjectivesObjectives Training Dive Two - Training Dive Two - ObjectivesObjectives


Training Dive Two - Training Dive Two - ObjectivesObjectivesTraining Dive Two - Training Dive Two - ObjectivesObjectives

Working within a teamWorking within a team• Rig gearRig gear• AA GGood ood DDiver’s iver’s MMain ain OObjective bjective IIs s TTo o LLiveive• BBeing eing WWary ary RReduces educes AAll ll FFailuresailures

Plan and execute a simulated trimix Plan and execute a simulated trimix accelerated decompression diveaccelerated decompression dive

Deploy a lift bag and ascend along theDeploy a lift bag and ascend along thelift bag line following thelift bag line following thedecompression schedule decompression schedule continued…continued…

Working within a teamWorking within a team• Rig gearRig gear• AA GGood ood DDiver’s iver’s MMain ain OObjective bjective IIs s TTo o LLiveive• BBeing eing WWary ary RReduces educes AAll ll FFailuresailures

Plan and execute a simulated trimix Plan and execute a simulated trimix accelerated decompression diveaccelerated decompression dive

Deploy a lift bag and ascend along theDeploy a lift bag and ascend along thelift bag line following thelift bag line following thedecompression schedule decompression schedule continued…continued…


Training Dive Two - Training Dive Two - ObjectivesObjectivesTraining Dive Two - Training Dive Two - ObjectivesObjectives

Respond to simulated emergenciesRespond to simulated emergencies Monitor and record depth, time and gas Monitor and record depth, time and gas

supply informationsupply information Complete dive mission assignedComplete dive mission assigned Demonstrate time, depth and gas supply Demonstrate time, depth and gas supply

awarenessawareness

Respond to simulated emergenciesRespond to simulated emergencies Monitor and record depth, time and gas Monitor and record depth, time and gas

supply informationsupply information Complete dive mission assignedComplete dive mission assigned Demonstrate time, depth and gas supply Demonstrate time, depth and gas supply

awarenessawareness

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Trimix2

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Transcript of Trimix2