Lesson 4: Flotation

1

Flotation Introduction Why are small boats required to have flotation, and why are

there different requirements?

Back in the 1950's and 60's the old Boating Industry

Association (now NMMA) and the Yacht Safety Bureau (now

ABYC) realized that one of the main reasons people died in

boat accidents was the boat sank out from under them. It

sounds obvious, but at the time it wasn't. Then in the

1970's a lot of research was done into hypothermia, and the

two came together. It was realized that if the boat did

not sink, it would give the people something to hang onto,

something that could be seen much better than just a head

sticking out of the water, and if the boat, although full

of water, did not sink, or roll over, then the people could

actually stay in the boat. Most of their torso would be

out of the water reducing the effects of hypothermia, and

providing a much better rescue platform.

So work started on developing a standard for flotation.

Through testing and experiments, techniques were developed

that would provide enough flotation to keep a small boat

afloat, and floating relatively level. However, this did

not work well for inboard boats, because the size and

weight of the engines required far too much flotation

material to float the boat level.

Meanwhile the Federal Boat Safety Act passed in 1971 and

went into effect in 1972. Even before that in 1969, the

Coast Guard had begun collecting statistical data on

boating accidents. Analysis of this data revealed that the

most significant contributors to fatalities were capsize,

sinking and falls overboard. Flotation in a boat could

eliminate the sinking, prevent capsizing, and prevent some

of the falls overboard. Many of the "falls overboard" were

actually the boat rolling over and dumping everyone in the

drink. Also, analysis revealed that by far the majority of

these accidents occurred in monohulled boats under 20 feet

in length, manually propelled or with outboard power. The

inboards contributed some of the fatalities.

NMMA, ABYC, and the Coast Guard determined that monohull

boats under 20 feet with outboard power or manually

propelled should have level flotation, and inboard boats,

basic flotation. Basic flotation simply keeps the boat

afloat with some of the boat sticking out of the water.

Lesson 4: Flotation

2

When the regulation was proposed many people in the classic

and wooden boat community felt that the level flotation

standard was too rigid to be applicable to small manually

propelled boats or boats with tiny engines. So after

testing and consultation with persons building these types

of boats the standard was modified to allow some latitude

in achieving the same performance. That is, these boats

have to float level to the same degree as larger boats with

bigger outboards, but the method of achieving it is

different. It was called modified level flotation.

Additionally small boats are allowed to carry a greater

percentage of their weight capacity as persons than larger

boats are and integral air chambers are allowed. This

seemed to satisfy everyone.

This particular standard has been very successful in

preventing deaths. It is not clear and probably not

quantifiable just how many deaths have been prevented but

the fatalities have dropped dramatically since 1972, but in

the United States, from about 19 per 100,000 boat, or about

1300 people, to less than 6 per 100,000 boats, about 600,

annually in 2005. At the same time the boating population

has grown to roughly 5 times what is was then. The drop in

fatalities is a combined result of education, engineering

and enforcement, so it is hard to say which has contributed

more, but certainly flotation standards have had an effect.

Finally; the flotation standard is a performance standard

that is, your boat must perform in a certain way. Rather

than make a rule that says something like, you must put so

many cubic feet of foam in your boat for every 160 pounds

per person, etc., this standard says how your boat must

perform under specific circumstances. The circumstances

are, loaded with an amount of weight determined by the

weight of the boat, the engine and the people, this boat

must remain afloat, in calm water, the way described in the

rule or standard. How you achieve this is left up to you

the builder.

In the ISO Standard for flotation ISO 12217 Small craft -- Stability and

buoyancy assessment and categorization -- Part 1: Non-sailing boats of hull length greater than or equal to

6m, and in the RCD, these test are performed in a different

manner. The principles are the same but the procedure is

different. For instance the weights used inside the boat in

the USA, are hung over the outside of the boat in the ISO

standard. In some instances this makes it more difficult to

Lesson 4: Flotation

3

pass the test. In others the results

are the same. The US Coast Guard and ABYC have done some

comparison tests using both methods. The results can vary

widely, so if you are using ISO or the RCD you will need to

obtain a copy of their standard. Additionally t6he ISO

standard covers stability and buoyancy for small sailboats

lees than or equal to 6 m. See the Appendix C for links to

various Standards.

Goals: Learn the rules and flotation standards for small

boats.

Learn how to test a boat to for Flotation.

I strongly suggest that to complete this course you obtain

the US Coast Guard Boatbuilders Handbook (the URL is below)

and the Canadian Rules (also given below). These are free

and will give you a lot of additional information. You can

purchase the others, but they will only benefit you if you

are planning on building boats for the European market. The

exception is the ABYC Standards. If you are building boats

I can’t recommend strongly enough joining ABYC and getting

copies of the standards either through on-line access, or

on CD, or printed.

The US Rules can be found at

http://uscgboating.org/regulations/boatbuilders-

handbook.php

The Canadian Rules can be found at

http://www.tc.gc.ca/eng/marinesafety/tp-tp1332-menu-521.htm

The Recreational Craft Directive for the EU can be found

at. http://www.rcdweb.com/ There is a fee for these

documents.

The ISO Standards for recreational boats are at

http://www.iso.org/iso/en/CatalogueListPage.CatalogueList?I

CS1=47&ICS2=80&ICS3=&scopelist= There is a fee for these

documents.

ABYC Standards can be found at htpp://www.abycinc.org There

is a fee for these documents for non-members. Members can

access these documents on-line.

Lesson 4: Flotation

4

The USA rules for Flotation are found

in Title 33 Code of Federal Regulations 183, Subparts F, G

and H, beginning at 183.101 to 183.335

The ABYC standards for Flotation are found in H-8, Buoyancy

In The Event Of Swamping.

The USA and ABYC Flotation Standards are divided into three

categories,

Definitions: From ABYC H-8

Basic Flotation: For inboard and sterndrive boats: A

flotation system that will keep a swamped boat from sinking

when its passengers are in the water clinging to it,

provided that the aggregate weight of the engine,

passengers and equipment carried in or attached to the boat

does not exceed that boat's maximum weight capacity. With

basic flotation the swamped boat may float at any attitude

Level Flotation: outboard powered boats over 2 HP (1.49

Kw); A flotation system that will keep a swamped boat and a

specified quantity of the weights of its engine, equipment,

and passengers floating in an approximately level attitude.

Sufficient stability is provided to prevent the swamped

craft from capsizing in calm water. Level flotation does

not provide a self-righting capability.

Modified Level Flotation: manually propelled boats, or

boats with 2 HP (1.49 KW) or less. - A flotation system

providing the same buoyancy as basic flotation but the

flotation material is arranged to achieve an approximately

level floating attitude.

Monohull: US Coast Guard Definition. Monohull boat: A boat

on which the line of intersection of the water surface and

the boat at any operating draft forms a single closed

curve. For example, a catamaran, trimaran, or a pontoon

boat is not a monohull boat.

ABYC Definition of Monohull Boat: Monohull boat – A boat on

which the line of intersection of the water surface and the

boat at any operating draft forms a single closed curve.

Lesson 4: Flotation

5

Basic Flotation

Applies to:

Monohulls under 20 feet (6m) which are:

inboards

sterndrives

airboats

jetboats

With inboard engines (gas, diesel, electric, stern-drive,

etc.):

Less than 20 feet (6m)(measured on the center line,

including rub rails):

This category includes most stern-drive and inboard motor

boats.

It does not include:

canoes kayaks

inflatables multihulls

submersibles raceboats

surface effect vehicles amphibious vehicles

sailboats

Exception

Mini Jet Boats must meet either:

FED REGS – Basic (33 CFR 183.101)

Or:

ABYC H-8, 8.5.1 – Level Flotation

Requirements:

The boat has to float when swamped, (that is; full of

water), with some part of the boat out of the water.

So how do I test the boat to see if it meets the standard?

To test the boat you need to know the following:

Lesson 4: Flotation

6

The maximum weight capacity (the safe

load – covered in Lesson 3) your boat will carry. This can

be found on the capacity label or taken from your capacity

calculations.

How much weight in people it will carry, that is, the

persons capacity.

The machinery weight: the weight of the engine.

These will be used to determine the amount of weight to

load into the boat to test it for flotation.

Then measure the following reference areas on your boat.

Reference areas are specific areas on the boat where

weights representing the load are placed.

Cockpit area: 40% reference area.

Passenger area: 70% reference areas.

Two foot reference areas fore and aft.

Fig 1

Lesson 4: Flotation

7

Fig 2

Measuring reference areas:

First determine what is the cockpit, or passenger carrying

area of the boat. This is different on every boat. Measure

the length of this area. Divide the length in half. Measure

from one end or the other, to the mid point of the length.

Then multiply the length by 0.20 (20%) and measure that

distance aft of the midpoint and the same amount forward of

the midpoint. That is 40% of the length of the passenger

carrying area.

Repeat for the width. Measure the width of the passenger

carrying area. Divide by half and mark the midpoint. Then

measure 20% to one side and 20% to the other side. This

area can be marked off with duct tape, which won’t damage

the boat and can be easily removed after the test. (see

photographs illustrating this in the section on level

flotation)

Then you need to load the boat with the following weights:

2/15 of the Person Capacity.

25% of the Dead Weight.

Dead Weight = Maximum Weight Capacity - Persons Weight

(this figure can be zero or negative. If negative use zero)

Lesson 4: Flotation

8

62.4 times the volume of the 2 largest

air chambers in cubic feet, if you used air chambers. If

air chambers are used; the 2 largest will be punctured and

flooded during the test. (I cubic meter = 1 metric ton or

1000 kg or 1 liter= 1 kg)

Air chambers integral with the hull are not allowed. (33

CFR 183.112(b))

Note: The weights you use do not weigh the same under

water, so they must be multiplied by a factor to compensate

for their “loss” of weight when submerged. For instance,

iron weights have to be multiplied by a factor of 0.86.

A ten pound iron weight would weigh 8.6 lbs (4.53 kg X .86

= 3.9 kg) under water. So you must then add weights to make

up the difference. For instance, if your persons weight is

1124 pounds, then 2/15 that is 150 pounds. So you need to

put 150 pounds in the boat. But 150 pounds of iron does not

weigh 150 pounds under water. To get the correct amount

divide the weight by 0.86 to get how much you actually need

to put on the boat.

150 lb/ 0.86 = 174.42 lb. (68.04 kg x 0.86 = 58.5 kg) This

is the amount you would load into the boat. However if the

weight will be dry (even though the boat is swamped) do not

compensate. Use the actual weight. In some cases the

weight for the engine may stay completely out of the water,

and weights placed on seats or on top of fuel tanks may be

out of the water. All of this depends on how much flotation

the boat has and how high it sits when swamped. At the end

of this lesson in Appendix C is a table of Material

Conversion Factors. You will also use this table

extensively in Lesson five when calculation amounts of

flotation.

Initially the boat is flooded with water and allowed to

soak for 18 hours. Then the weights for the basic flotation

test are added, and if any part of the boat is above the

water it passes. With this weight aboard and the boat fully

swamped, it must float with some part of the boat out of

the water.

ABYC H-8.7.3.1.2, SAYS THAT IN ADDITION TO THE ABOVE:

“WEIGHTS THAT, WHEN SUBMERGED, EQUALS 75% OF THE DRY

WEIGHTS OF THE PROPULSION SYSTEM AND BATTERIES."

Lesson 4: Flotation

9

ABYC assumes you will test without the engines and

sterndrive installed. The Coast Guard tests the boat

with the engines installed but removes the sterndrive

and batteries, and substitutes weights.

The biggest difficulty with the basic flotation test is

finding a test tank or pool that is deep enough. Often the

boat is almost vertical with only the bow out of the water.

If the pool is only 6 or 7 (2.13 m)feet deep the stern of

the boat will be resting on the bottom of the tank.

Sometimes by shifting weights forward you can level out the

boat so it can be tested in a shallower tank.

Lesson 4: Flotation

10

Level Flotation:

Applies to:

Mono-hull outboard boats (not catamarans, trimarans, or

pontoon boats. Mono-hull means that if you can draw a

continuous line around the hull at the waterline when the

boat is at rest it's a mono-hull. If it makes two or more

footprints in the water it's a multi-hull.

Greater than 2 Horsepower (1.49 kw):

Less than 20 (6 m) feet (measured on the center line,

including rub rails):

It does not include:

canoes kayaks

inflatables multihulls

submersibles raceboats

surface effect vehicles amphibious vehicles

sailboats

This category includes most outboard motor boats.

Requirements:

The boat has to float when swamped, (that is; full of

water), in an upright level attitude. See the diagrams in

each test for specific requirements.

At the end of this lesson in Appendix B, are tables of

weights for outboard motors, batteries and portable fuel

tanks. Table 4 is from The US CFR 183, and Tables 1a and

1b are from ABYC Standard S-30. These tables must be used

for calculating capacity, and flotation, and for doing the

flotation test. Do not use the actual weight of any

particular outboard. The weights of the heaviest outboards

are included in the tables. This is so no matter which

brand the owner of the boat uses, they will have enough

flotation to float level.

To test the boat you need to know the following:

1. The maximum weight capacity (the safe load – covered in

Lesson 3) your boat will carry.

Lesson 4: Flotation

11

2. The weight of the persons. This

comes from the persons weight on the capacity label or your

capacity calculations.

3. The machinery weight: the weight of the engine from

Table 4 or the ABYC tables

These will be used to determine the amount of weight to

load into the boat to test it for flotation.

Then measure the following reference areas on your boat.

Reference areas are specific areas on the boat where

weights representing the load are placed.

The cockpit area. 40% reference area.

The following photos illustrate measuring the 40% reference

area

Photo #1

Lesson 4: Flotation

12

Photo #2

The passenger carrying area: 70% reference areas.

The two foot (61 cm) reference areas fore and aft.

There are three tests to do.

The first is the level flotation test, after an 18 hour

soak.

Put your boat in the water. Put half the persons weight in

the boat assuming the maximum persons weight is less than

550 pounds. If over 550 pounds (249.5 kg), add 0.125 (1/8)

times persons weight minus 550) in the 40% reference area.

The Center of Gravity of all the weights needs to be in the

40% reference area. That doesn't mean all the weights have

to be in the 40% area, just the Center of Gravity of all

the weights.

Place weights to simulate the engine in a basket on the

transom. You get this weight from table 4 column 2, Swamped

Engine weights, or column 4 from the ABYC table. Why

swamped? Because only the lower portion of the engine will

Lesson 4: Flotation

13

be underwater. The center of gravity

of the engine weights must be no more than three inches aft

of the transom and no more than three inches above the top

of the transom.

Place weights to simulate the battery in the position where

the battery is normally mounted. This weight comes from

Table 4 Column 4, Submerged Battery Weights, or ABYC table

column 8. If no position for the battery is indicated, put

them on the centerline of the boat. Place weights to

simulate the full portable full tank, also from Table 4 or

the ABYC table, in the position where the tank would be

placed or if no position is indicated, on the centerline.

If the boat has a permanently installed full tank, either

fill the tank ¾ full of water, or use weights to simulate

the weight of the tank. These weights should be place so

their center of gravity is a close to where the tanks

center of gravity would be.

Pull the plug! Let the boat fill up with water. Leave it

that way for 18 hours. Fig 3

Lesson 4: Flotation

14

The 18 hour soak is primarily designed

to get trapped air out of areas on the boat. To test the

boat properly you should drill small holes in areas where

air may be trapped, open up the backs of upholstered seats

and open hatches or covers to compartments. All areas of

the boat should be flooded. The easiest way to do the 18

hour soak is to prepare the boat in the afternoon, put it

in the water at four or five pm, and let it sit overnight.

You can then test it first thing in the morning.

Test 1. After the 18 hour soak the boat should float in the

following way:

One end out of the water.

The other end 6 (15.24 cm) inches or less under water (or

out of the water too) measured at the 2 foot (61 cm)

reference area.

No more than a 10 degree heel angle. (You can buy a device

at a hardware store that measures this. See Photo #4).

TEST 2. The second test is the stability test. You need to

do this one twice, once on each side of the boat.

Place half the weight for persons on one side of the boat.

The center of gravity of these weights has to be in the 70%

reference area on that side of the boat. You have a lot of

lee way here. You can move the weights from front to back,

or back to front to get the boat to pass as long as the

Center of Gravity is in the 70% area, and 30% of the total

passenger weight is in the 70% area.

Take the other half of the passenger weight out of the

boat.

Leave the engine, batteries, fuel and control weights where

they are.

WARNING! Make sure you have some ropes or straps attached

to the boat to keep it from rolling over. If you don't have

enough flotation to keep it upright, that's what it will

do. Then the weights will fall out and go to the bottom of

the pool or lake. When it settles down it should float like

this. (See diagram)

Lesson 4: Flotation

15

Fig 4

The final results should be:

One end out of the water.

The other end 12 inches (30.48 cm)or less under water (or

out of the water too) measured at the 2 foot (61 cm)

reference area.

No more than a 30 degree heel angle.

Experience has shown that if it goes 30 degrees it will

probably roll all the way over.

Lesson 4: Flotation

16

Photo #3 above, Photo #4 below

REPEAT THIS TEST ON THE OTHER SIDE.

Lesson 4: Flotation

17

TEST 3. The final test is without the

passenger weights.

Take all of the passenger weight out of the boat. Leave

the engine batteries and gear weights where they are. Let

the boat settle

Fig 5

The final result should be:

One end out of the water.

The other end 6 inches (15.24 cm)or less under water (or

out of the water too) measured at the 2 foot reference (61

cm) area.

No more than a 10 degree heel angle.

Lesson 4: Flotation

18

Modified Level Flotation: Applies to:

Mono-hull Boats (not catamarans, trimarans, or pontoon

boats): Mono-hull means that if you can draw a continuous

line around the hull at the waterline when the boat is at

rest it's a mono-hull. If it makes two or more footprints

in the water it's a multi-hull. I am repeating this

definition because a lot of small pedal boats and small

fishing boats are not mono-hulls until you put the

passengers in them. With this load they are monohulls and

must meet this standard.

Less than 2 Horsepower (1.49 kw), gas or electric outboard

motor, or:

Manually propelled. (Oars, sculls, paddles or pedals, etc.)

This category includes most dinghies and rowboats, and some

small john boats.

Requirements:

The boat has to float when swamped, (that is; full of

water), in an upright attitude. See the diagram in each

test for the specific requirements.

To test the boat for modified level flotation, you need to

know the following:

The maximum weight capacity (the safe load) your boat will

carry. This is taken from the capacity label or from your

capacity calculations.

How much weight in people it will carry. This is also taken

from the capacity label or from your capacity calculations.

If you want to use 2 horsepower (1.49 kw) or less you need

the engine weight: = 25 lb. (11.34 kg)

Then measure the following reference areas on your boat:

Cockpit area. 40% reference area.

Passenger area 70% reference areas.

Lesson 4: Flotation

19

Two foot reference areas fore and aft.

These are the same as the reference areas for Basic

flotation and level flotation.

There are three tests to do.

TEST 1. The first is the level flotation test after an 18

hour soak.

Put your boat in the water. Put half the persons weight in

the boat assuming the maximum persons weight is less than

550 pounds. If over 550 pounds (249.5 kg), add 0.125 (1/8)

times persons weight minus 550) in the 40% reference area.

The Center of Gravity of all the weights needs to be in the

40% reference area. That doesn't mean all the weights have

to be in the 40% area, just the Center of Gravity of all

the weights.

Pull the plug! Let the boat fill up with water. Leave it

that way for 18 hours. When done it should float like this:

Fig 6

Lesson 4: Flotation

20

One end out of the water.

The other end 6 (15.24 cm) inches or less under water (or

out of the water too) measured at the inner side of the 2

foot reference (61 cm) area, at the centerline of the boat.

No more than a 10 degree heel angle. (You can buy a device

at a hardware store that measures this).

TEST 2. The second test is the stability test. You need to

do this one twice, once on each side of the boat.

Place half the weight for persons on one side of the boat.

The center of gravity of these weights has to be in the 70%

reference area on that side of the boat. You have a lot of

lee way here. You can move the weights from front to back,

or back to front to get the boat to pass as long as the

Center of Gravity is in the 70% area, and 30% of the total

passenger weight is in the 70% area.

Take the other half of the passenger weight out of the

boat.

If this is a 2 HP 1.49 kw)or less boat, leave the 25 lbs

(11.33 kg) where it is.

WARNING! Make sure you have some ropes or straps attached

to the boat to keep it from rolling over. If you don't have

enough flotation to keep it upright, that's what it will

do. Then the weights will fall out and go to the bottom of

the pool or lake.

Lesson 4: Flotation

21

Fig 7

One end out of the water.

The other end 12 inches (30.48 cm) or less under water (or

out of the water too) measured at the 2 foot (61 cm )

reference area.

No more than a 30 degree heel angle.

Experience has shown that if it goes 30 degrees it will

probably roll all the way over.

REPEAT THIS TEST ON THE OTHER SIDE.

TEST 3. The final test is without the passenger weights.

Take all of the passenger weight out of the boat. Let the

boat settle

Lesson 4: Flotation

22

Fig 8

One end out of the water.

The other end 6 inches (15.24 cm) or less under water (or

out of the water too) measured at the inner side of the 2

foot (61 cm) reference area, at the centerline of the boat.

No more than a 10 degree heel angle.

Some procedures to be used during testing

Permanently Installed Fuel Tanks:

20 Gals (75.7 L) or Less. Place weight of fuel on deck over CG of Fuel Tanks.

Greater Than 20 Gal. (75.7 L) : Initially same as above. If boat fails fill tank to ¾

level with water. If still fails fill tank full with water.

Time Allowed to stabilize between tests: 15 minutes.

Hull to Deck Joint:

Seal Hull to deck Joint with tape on all boats prior to test.

Lesson 4: Flotation

23

Location Of Outboard Motor Weight

3 Inches aft of transom. (+/- 1 inch) (7.62 cm)

3 inches above transom. (+/- 1 inch) (7.62 cm)

Flooded Bait Wells During Flotation Tests

Remove riser from drain hole and let bait well flood /drain naturally.

Trolling Motor Weight for Flotation Test.

If equipped with or wired for a trolling motor, the trolling motor and battery are to

be considered gear weight.

Kicker Motors:

If the boat is equipped with a pad or wiring for a kicker motor then flotation must

be provide for the submerged weight of motor and controls.

If the manufacture of the boat does not specify the horsepower for the kicker motor

the the horsepower will be assumed to be 10% of the main motor’s horsepower.

Weights will be from table 4 .

How do I know it works? Test it!

The best way to find out if your boat passes is to test it.

You can do the test yourself, or have a laboratory do it,

or if you are newly in business as a boat builder the Coast

Guard will do it for you. Call the Coast Guard at 1-202-

372-1073.

Lesson 4: Flotation

24

Questions

1. The level flotation standard applies to:

a. Outboard boats of two horsepower or less b. Inboard and sterndrive boats c. Manually propelled boats d. Outboard powered boat over 2 hp (1.49Kw) ***

2. Level flotation will keep a swamped boat afloat when loaded with specified weights. It will also;

a. Make the boat self righting b. Keep the boat from heeling more than 30 degree in

calm water ***

c. Allow the boat to float with a heel angle greater than 30 degrees.

d. None of the above.

3. A steel weight weighs 55 lbs out of the water. If there are two 55 lb steel weights, and during the test

one is submerged and the other is out of the water,

what is the combined weight.

a. 103.4 lb (46.89kg) *** b. 102.3 lb (46.39kg) c. 96.8 lb (43.9kg) d. 110 lb (49.88kg)

(48.4 + 55)=103.4 (21.95kg + 24.94kg=46.89kg) ***

(47.3 + 55) = 102.3 (21.45kg+24.94kg=46.39kg)

(48.4 + 48.4) = 96.8 lbs (21.95 x 2 =43.9kg)

(55 + 55) = 110 lbs (24.94 X 2 = 49.88kg)

4. When a boat has basic flotation it may float:

a. In a level attitude with one end out of the water b. At any attitude with any part of the boat out of

the water ***

c. Must float at less than 30 degree heel angle and upright

d. None of the above.

Lesson 4: Flotation

25

5. A 19 foot catamaran with an outboard motor under the US CFR, requires

a. Level Flotation b. Basic Flotation c. Modified level flotation d. No Flotation. ***

6. A 16 foot outboard motor boat is tested for flotation with the following results. The first test after the

18 hour soak with persons and gear weight; The heel

angle is 11 degrees, the bow is out of the water and

the stern is 4 inches underwater at the 2 foot

reference area measured at the centerline. Does this

boat pass or fail?

a. Pass b. Fail *** (10 degrees is the limit)

7. The minimum flotation standard that would apply to a small dinghy with a 2 hp (1.49 Kw) motor would be?

a. Basic Flotation b. Modified level flotation *** c. Level Flotation d. This boat is not required to have flotation.

8. Which of the following must have flotation?

a. canoe

b. kayak

c. pedal boat with two hulls

d. rowboat ***

9. A single 150 Hp (111.85 Kw) engine is used on an outboard boat. What is the total swamped weight of the

engine. Use Table 4 from the US CFR, and the value for

fresh water.

a. 540 lb(244.9 kg) b. 450 lb(204.1 kg) c. 380 lb(172.4 Kg) **** d. 405 lb, 6.7 cu ft (183.7 kg, .184 cu meters)

Lesson 4: Flotation

26

10. An outboard boat is tested for level flotation. On the stability test, when measured

at the aft 2 foot reference area the measurement must

be at least.

a. 6 inches b. 12 inches ***** c. 30 degrees d. 10 degrees

Lesson 4: Flotation

27

Appendix A

Table 4 from 33CFR183

Weights of Outboard Motors and Related Equipment For

Various Boat Horsepower Ratings

Boat Horsepower

Rating

Motor and Control

Weight Battery weight

Full

Portable

Fuel Tank

Weight

column

Dry Swamped Dry Submerged 1+3+5

1 2 3 4 5 6

.01 to 2 25 20 - - - 25

2.1 to 3.9 40 34 - - - 40

4.0 to 7 60 52 - - 25 85

7.1 to 15 90 82 20 11 50 160

15.1 to 25 125 105 45 25 50 220

25.1 to 45 170 143 45 25 100 315

45.1 to 60 235 195 45 25 100 380

60.1 to 80 280 235 45 25 100 425

80.1 to 145 405 352 45 25 100 550

145.1 to 275 430 380 45 25 100 575

275.1 and up 605 538 45 25 100 750

Transoms Designed for Twin Motors

50.1 to 90 340 286 90 50 100 530

90.1 to 120 470 390 90 50 100 660

120.1 to 160 560 470 90 50 100 750

160.1 to 290 810 704 90 50 100 1000

290.1 to 550 860 760 90 50 100 1050

550.1 and up 1210 1076 90 50 100 1400

Below are tables 1a and 1b published in ABYC Industry

Conformity Standard S-30, Outboard Engine and Related

Equipment Weights. It is updated on a five year cycle and

contains the weights for four stroke outboards..

Lesson 4: Flotation

28

Lesson 4: Flotation

29

Lesson 4: Flotation

30

Appendix B

© 2004 American Boat & Yacht Council, Inc.

Lesson 4: Flotation

31

Appendix C

The US Rules can be found at

http://uscgboating.org/regulations/boatbuilders-

handbook.php

The Canadian Rules can be found at

http://www.tc.gc.ca/eng/marinesafety/tp-tp1332-menu-521.htm

The Recreational Craft Directive for the EU can be found

at. http://www.rcdweb.com/ There is a fee for these

documents.

The ISO Standards for recreational boats are at

http://www.iso.org/iso/en/CatalogueListPage.CatalogueList?I

CS1=47&ICS2=80&ICS3=&scopelist= There is a fee for these

documents.

ABYC Standards can be found at htpp://www.abycinc.org There

is a fee for these documents for non-members. Members can

access these documents on-line.