Advanced Piloting Course (Coastal Navigation) Chapter 8 Effects of Winds/Current Educational Officer – Dave West Assistant Educational Officer – David Moberg – Instructor – Art Mollica United States Power Squadrons ®

2 APPENDIX A - WEEKEND CRUISE PART 4

3 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 QHG1 MPG1

a) Using the tide charts for Gay Head determine if you could raft up with your friend at 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 Seabed COG 276M C 276M Course through water Course Over Ground

Slide 8 With Current – Crabbing Seabed COG 265M C 276M Steered 276M Course Over Ground

Slide 9 With Wind – Leeway Seabed 3º3º C 276M Steered 276M Course Over Ground 273M

Slide 10 Watch Your Wake Steering steady course No current/leeway Course steered Current/leeway Course steered

Slide 11 Three Variables With CurrentAgainst Current C 115M Current C 295M Current Cross Current Current C 115M 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 landAway from landSlack 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% 90% 100% 1/3 Maximum Flood Speed Maximum Ebb Speed Slack Flood Ebb

Slide 14 Rule of Twelfths (50-90) Slack Water Max Flood Slack Water Max Ebb Slack Water hr 45 min = 345 min / 3 = 115min 4 hr 21 min = 261 min / 3 = 87min 2 hr 39 min = 159 min / 3 = 53min 2 hr 57 min = 177 min / 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% 50% 50% 90% 90% 50%

Slide 15 Table 1

Slide 16 Table 2

MINUTE BREAK PLEASE TAKE YOUR SEATS

Slide 18 Estimating Current One 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 1 Location: Marblehead Channel (Sub-Station 996) Reference Station: Boston Harbor (Deer Island) Calculate speed & direction on 18 May EDT Figure 8-4 & 8-5 Marblehead Channel 998 Boston Harbor (Deer Island) 18 May E E E 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 8-1 Location: 0.2nm west of West Chop, Ma (Sub-Station 1941) Calculate speed & direction on 1 Sep EST West Chop 0.2nm West 1941 Pollack Rip Channel 1 Sep F F F

Slide 21 Exercise 8-2 Location: Waquoit Bay Entrance (Sub-Station 1926) Calculate speed & direction on 26 Aug EST Waquoit Bay Entrance 1926 Pollack Rip Channel 26 Aug E E E

Slide 22 Exercise 8-3 Location: Southeast of Nobska Point (Sub-Station 1946) Calculate speed & direction on 24 Sep EST Nobska Point 1946 Pollack Rip Channel 24 Sep F F F0 ----

Slide 23 Exercise 8-4 Location: 0.8 miles east of Yellow Bluff (Sub-Station 551) Calculate speed & direction on 1 Sep PST 0.8 miles east of Yellow Bluff 1946 Golden Gate Bridge 1 Sep F F F

Slide 24 Exercise 8-5 Location: Richardson Bay Entrance (Sub-Station 601) Calculate speed & direction on 26 Aug PST Richardson Bay Entrance 1946 Golden Gate Bridge 26 Aug E E F

Slide 25 Exercise 8-6 Location: 0.75 miles east of Angel Island (Sub-Station 586) Calculate speed & direction on 24 Sep PST 0.75 miles east of Angel Island 1946 Golden Gate Bridge 24 Sep E E F

Advanced Piloting Course (Coastal Navigation) Chapter 9 Piloting with Wind/Currents Educational Officer – Dave West Assistant Educational Officer – David Moberg – Instructor – Art Mollica 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 Steer Use same baseline for each vector Distance between 1130DR and 1130 GPS = 4nm Direction from 1130DR to 1130 GPS = 042 º Time = 2hrs COG 305M 0930 GPS 1030 GPS GPS Set 042 Dft 2.0 C 305M S 10.0 C 295M S 10.0 C 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 D = ST S = 60 X 4.0 / 120 Dft = 2.0nm

Course to Steer Use same baseline for each vector Exercise 8-1 Computed Set 059 º 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 GPS M D4.5 60D = ST D = 10.0 X 31 / 60 D = 5.16 = T = 002 V = 15 W M = D = ST S = 60 X 1.2 / 31 S = 2.3nm T = 236 V = 15 W M = 251 M = 239 V = 15 W T = 224 Set 017M Dft 2.3 T = 212 V = 15 W M = 227 C 227M S 10.0 CMG 262M SMG 9.0 T = 247 V = 15 W M = 262 COG 239M 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 242M 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 242M S 11.0 BBG5 NLT 251M Exercie 9-2

C 255M Track T = 250 V = 15 W M = 265 Set T = 355 V = 15 W M = 010 Course 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 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 ORR Visual D – 0945 = 0115 = 75 min 60D = ST S = 60x6.6 / 75 S = 5.27 = 5.3kn C 029M S 6.8 T = 014 V = 15 W M = – 0945 = 45 min 60D = ST D = 6.8 X 45 / 60 D = GPS kn T = 117 V = 15 W M = D = ST S = 60x1.1 / 45 S = 1.5 Set 132M Dft Visual T = 159 V = 15 W M = 174 T = 175 V = 15 W M = 190 Set 132M Dft 1.5 COG 174M SOG 5.0 C 190M S M 174M 5.0kn 60D = ST T = 60x6.2 / 5.0 T = = C 190M S 4.0 Exercise 9-3

Slide 34 Questions ? … Comments

Slide 35  Finish Weekend Cruise  Next Class – 24 May Homework