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Transcript of Advanced Piloting Course (Coastal Navigation) Chapter 8 Effects of Winds/Current Educational Officer...
Advanced Piloting Course (Coastal
Navigation)
Chapter 8
Effects of Winds/Current
Educational Officer – Dave [email protected] - 651-429-3840
Assistant Educational Officer – David Moberg
[email protected] – 715-386-8582 Instructor – Art Mollica
[email protected] - 651-777-0277
United States Power Squadrons®
22APPENDIX A - WEEKEND CRUISE
PART 4
33
24) You arrive at “1” BELL at the entrance to Menemsha Basin at 1300 and secure your boat to a dock. You call your friend and he tells you to check the tide charts to determine when you will be able to raft up to him. His dock is in 3’ of water at MLW. You need 2’ of clearance & your boat draws 3.0 feet.
24) You arrive at “1” BELL at the entrance to Menemsha Basin at 1300 and secure your boat to a dock. You call your friend and he tells you to check the tide charts to determine when you will be able to raft up to him. His dock is in 3’ of water at MLW. You need 2’ of clearance & your boat draws 3.0 feet.
1300
QHG1
MPG1
44
04 54
24a) Using the tide charts for Gay Head determine if you could raft up with your friend at 1400. Will you have enough water for clearance? NO clearance 12 inches under keel
24b) Which government agency is located at Menemsha Basin? Coast Guard
Slide 5
Currents – Horizontal Movement
Flood Current – from sea towards shore or up tidal river or estuary
Ebb Current – away from shore or down a tidal river or estuary
Slack – time at which horizontal movement stops
Slide 6
Why Worry About Currents
Slide 7
Perfect World – No Currents
SeabedCOG 276M
C 276MCourse through water
Course Over Ground
Slide 8
With Current – Crabbing
Seabed
COG 265M
C 276MSteered 276M
Course Over Ground
Slide 9
With Wind – Leeway
Seabed3º
C 276MSteered 276M
Course Over Ground 273M
Slide 10
Watch Your Wake
Steering steady course
No current/leewayC
ours
e s
teere
d
Current/leeway
Cours
e s
teere
d
Slide 11
Three VariablesWith Current Against Current
C 115M
Current
C 295MCurrent
Cross Current
Current
C 115M
S 8.0 S 8.0
SOG 9.5 COG 115M
SOG 6.5 COG 295M
1.5kn current
SOG ??? COG ???M
Slide 12
Current Vectors
Current Direction – Set
Current Speed – Drift
From sea toward land
Away from land
Slack water
Not Always Opposite Directions
Different Maximum Speeds
FLOOD 095
EBB 255
Slide 13
Rule of Twelfths (50-90)
Slack Water
Time Intervals
90%
100%
50%
50%
90%
100%1/3 1/3 1/3 1/3 1/3 1/3 1/3 1/3 1/3 1/3 1/3 1/3
Maxim
um
Flo
od S
peed
Maxim
um
Ebb S
peed
Sla
ck
Sla
ck
Sla
ck
Flood
Eb
b
Slide 14
Rule of Twelfths (50-90)Slack Water 0421
0616
0811
Max Flood 1006
1133
1300
Slack Water 1427
1520
1613
Max Ebb 1706
1805
1904
Slack Water 2003
5hr45min = 345min / 3 = 115min
4hr21min = 261min / 3 = 87min
2hr39min = 159min / 3 = 53min
2hr57min = 177min / 3 = 59min
0.0kn
0.8kn
1.4kn
1.5kn
1.4kn
0.8kn
0.0kn
1.3kn
2.3kn
2.6kn
2.3kn
1.3kn
0.0kn
50%
90%
90%
50%
50%
90%
90%
50%
Slide 15
Table 1
Slide 16
Table 2
10 9 8 7 6 5 4 3 2 1
10 MINUTE BREAK
PLEASE TAKE YOUR SEATS
Slide 18
Estimating CurrentOne Part at a Time
• Slack to Max Flood/Ebb
• Max Flood/Ebb to Slack
• Slack to Max Flood/Ebb
• Max Flood/Ebb to Slack
Determine Time Interval
Use Percentages
• Slack to Max
• Max to Slack
Slide 19
Example 1Location: Marblehead Channel (Sub-Station 996)
Reference Station: Boston Harbor (Deer Island)
Calculate speed & direction on 18 May 2004 1400 EDT
Figure 8-4 & 8-5
Marblehead Channel 998Boston Harbor (Deer Island)
18 May 2004 1300
10261429 E 1.2
+ 01 09+ 01 09 0.3
11351538 E 0.4 105
153811350403243
81
1135 1256
81
1417
81
1538
81
0.4E 50 0.2 105
Figures 8-7 & 8-9
JJ – Exercise 8-1
Chris G – Exercise 8-2
Karen – Exercise 8-3
Figures 8-11 & 12
Terry – Exercise 8-4
Dean – Exercise 8-5
Chris S – Exercise 8-6
Slide 20
Exercise 8-1Location: 0.2nm west of West Chop, Ma (Sub-Station 1941)
Calculate speed & direction on 1 Sep 2004 1000 EST
West Chop 0.2nm West 1941Pollack Rip Channel
1 Sep 2004 1000
0751 F1056
2.2 + 01 34+ 01 50
1.3 0925 F1246
2.9 059
124609250321201
67
0925 1032
67
1139
67
1246
67
2.9F 90 2.6 059
Slide 21
Exercise 8-2Location: Waquoit Bay Entrance (Sub-Station 1926)
Calculate speed & direction on 26 Aug 2004 1100 EST
Waquoit Bay Entrance 1926Pollack Rip Channel
26 Aug 2004 1100
0811 E0536
1.4 + 04 01+ 03 40
0.8 1212 E0916
1.1 203
121209160256176
59
0916 1015
59
1114
59
1213
59
1.1E 90 1.0 203
Slide 22
Exercise 8-3Location: Southeast of Nobska Point (Sub-Station 1946)
Calculate speed & direction on 24 Sep 2004 0100 EST
Nobska Point 1946Pollack Rip Channel
24 Sep 2004 0100
0210 F2225
1.8 + 02 15+ 02 33
1.3 0425 F0058
2.3 071
042500580327207
69
0058 0207
69
0316
69
0425
69
0.0F 0 0.0 ----
Slide 23
Exercise 8-4Location: 0.8 miles east of Yellow Bluff (Sub-Station 551)
Calculate speed & direction on 1 Sep 2004 1000 PST
0.8 miles east of Yellow Bluff 1946Golden Gate Bridge
1 Sep 2004 1000
1122 F0819
3.6 + 00 15+ 00 19
1.0 1137 F0838
3.6 022
113708380259179
60
0838 0938
60
1038
60
1138
60
3.6F 50 1.8 022
Slide 24
Exercise 8-5Location: Richardson Bay Entrance (Sub-Station 601)
Calculate speed & direction on 26 Aug 2004 1100 PST
Richardson Bay Entrance 1946Golden Gate Bridge
26 Aug 2004 1100
1243 E1507
1.0 - 02 34-03.06
0.3 1009 E1201
0.3 225
120110090152112
37
1009 1046
37
1123
37
1200
37
0.3F 90 0.3 225
Slide 25
Exercise 8-6Location: 0.75 miles east of Angel Island (Sub-Station 586)
Calculate speed & direction on 24 Sep 2004 0100 PST
0.75 miles east of Angel Island 1946Golden Gate Bridge
24 Sep 2004 0100
2342 E2000
2.2 + 01 50+ 01 33
0.5 0132 E2133
1.1 192
013221330359239
80
2133 2253
80
2413
80
0133
80
1.1F 100 1.1 192
Advanced Piloting Course (Coastal
Navigation)
Chapter 9
Piloting with Wind/Currents
Educational Officer – Dave [email protected] - 651-429-3840
Assistant Educational Officer – David Moberg
[email protected] – 715-386-8582 Instructor – Art Mollica
[email protected] - 651-777-0277
United States Power Squadrons®
Course
Direction Traveled Between Two Fixes
Actual Direction of Travel Over Ground
Current
Track
Speed
Speed of Advance Intended Speed along the Track (SOA)
Direction boat is steered (C)
Course Made Good (CMG) - Track Made Good (TMG)
Course Over the Ground (COG) Direction of flow (Set) – speed of current (Drift) Intended Direction of Movement (Trk)
Rate of motion through water (S)
Terminology
Course to SteerUse same baseline for each vector
Distance between 1130DR and 1130 GPS = 4nm
Direction from 1130DR to 1130 GPS = 042º
Time = 2hrs
COG 305M
0930 GPS
1030 GPS
1030
1130
1130 GPSSet 042 Dft 2.0
C 305M S 10.0
C 295MS 10.0C 295M S 10.0
Set 042
Dft 2.0
Determine course to steer to maintain COG 305M
Apply expected Set/Drift from 1130 GPS
Draw arc equal to boat speed = 10.0kn
Draw course from Set/Drift to intersection
Distance from 1130 GPS to intersection = SOG
From 1130 GPS draw course line at 295M
SOG 9.0
60D = ST S = 60 X 4.0 / 120 Dft = 2.0nm
Course to SteerUse same baseline for each vector
Exercise 8-1 Computed Set 059º Drift 2.6
What is course to steer to reach destination from N”3” at 15kn?
COG 130M
Dest
C 139M S 15.0
SOG 14.8
N “3”
Set 059 Dft 2.6
1hr
2hr
3hr
BBR4
BBG7
Plot waypoints R”4” Fl R 6s BELL as BBR4 and G“7” Fl G 4s as BBG7
Depart BBR4 at 1000 for BBG7, speed 10kn
At 1031, BBG7 bears 239ºM at 4.5nm
Determine set and drift and plot new course to BBG7
Qualify new course
1000 Visual
C 251M
S 10.0
1031 GPS
1031
239M
D4.5
60D = ST D = 10.0 X 31 / 60 D = 5.16 = 5.2
1031
T = 002 V = 15 W M = 017
60D = ST S = 60 X 1.2 / 31 S = 2.3nm
T = 236 V = 15 W M = 251M = 239 V = 15 W T = 224
Set 017M Dft 2.3
T = 212 V = 15 W M = 227 C
227
M
S 1
0.0
CMG 262M
SMG 9.0
T = 247 V = 15 W M = 262
COG
239
M
Set 017M Dft 2.3
SOG
9.0
Exercise 9-1
COG T = 236 V = 15 W M = 251
Set T = 355 V = 15 W M = 010
Course T = 227 V = 15 W M = 242
SOG 9.9
Set 010M Dft 2.1
COG 251M
C 242
M
S 11.
0
Plot waypoints R”4” Fl R 6s BELL as BBR4 and G“7” Fl G 4s as BBG7
Speed of advance is 9.9kn,
Set is 010ºM and drift is 2.1kn.
What is the course to steer?
What is the required boat speed?
Qualify the course.
What would you do?
BBG7
BBR4
C 242
M
S 11.
0
BBG5
NLT 251
M
Exercie 9-2
C 255M
Track T = 250 V = 15 W M = 265
Set T = 355 V = 15 W M = 010Course T
= 240 V = 15 W M = 255
SOA 9.9
Set 010M Dft 2.1
S 11.0
Trk 265M
BBR6
Track T = 211 V = 15 W M = 226
Trk
226M
C 255M
S 11.0
Plot waypoints R”4” Fl R 6s BELL as BBR4 and G“7” Fl G 4s as BBG7
Speed of advance is 9.9kn,
Set is 010ºM and drift is 2.1kn.
What is the course to steer?
What is the required boat speed?
Qualify the course.
What would you do?
BBG7
BBR4
Exercise 9-2 (another solution)
Plot waypoints RN”2” (Shark River) as SRR2 and R“2” Fl R (Oyster River) as ORR2 – depart ORR2 at 0945.
Minimum speed to arrive RN”2” by 1100?
You leave with boat speed of 6.8kn.
At 1030 your GPS position is L 41º 41.7’N Lo 71º 58.4’W - determine current set and drift.
You fish and end up at GC”3” at 1100 and decide to head back to ORR2 at a reduced speed of 4.0kn. Assume set/drift remains the same.
What is your DR course to ORR2?
What is your COG and SOG to ORR2?
What is your ETA at ORR2?
SRR2
ORR2 0945 Visual
D 6
.55
1100 – 0945 = 0115 = 75min
60D = ST S = 60x6.6 / 75 S = 5.27 = 5.3kn
C 0
29M
S
6.8
T = 014 V = 15 W M = 029
1030 – 0945 = 45min
60D = ST D = 6.8 X 45 / 60 D = 5.1
1030 GPS
1030
5.3kn
T = 117 V = 15 W M = 132
60D = ST S = 60x1.1 / 45 S = 1.5
Set 132M Dft 1.5
1100 Visual
T = 159 V = 15 W M = 174
T = 175 V = 15 W M = 190
Set 132M Dft 1.5
CO
G 174M
SO
G 5.0
C 190M
S 4.0
190M
174M 5.0kn
60D = ST T = 60x6.2 / 5.0 T = 74
1100 + 74 = 1214
1214
C 190M
S 4.0
Exercise 9-3
Slide 34
Questions ? … Comments
Slide 35
Finish Weekend Cruise
Next Class – 24 May
Homework