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Advanced Piloting Course (Coastal Navigation) Chapter 8 Effects of Winds/Current Educational Officer – Dave West dwest@voyager.net - 651-429-3840 Assistant Educational Officer – David Moberg davidmoberg@att.net – 715-386-8582 Instructor – Art Mollica artmollica@usfamily.net - 651-777-0277 United States Power Squadrons ®

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2 APPENDIX A - WEEKEND CRUISE PART 4

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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. 1300 QHG1 MPG1

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4 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

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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

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Slide 6 Why Worry About Currents

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Slide 7 Perfect World – No Currents Seabed COG 276M C 276M Course through water Course Over Ground

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

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

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

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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

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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

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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

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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 5 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%

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Slide 15 Table 1

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Slide 16 Table 2

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10987654321 10 MINUTE BREAK PLEASE TAKE YOUR SEATS

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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

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Slide 19 Example 1 Location: 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 998 Boston Harbor (Deer Island) 18 May 2004 1300 1026 1429 E1.2 + 01 09 0.3 1135 1538 E0.4 105 1538 1135 0403 243 81 1135 1256 81 1417 81 1538 81 0.4E500.2105 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

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Slide 20 Exercise 8-1 Location: 0.2nm west of West Chop, Ma (Sub-Station 1941) Calculate speed & direction on 1 Sep 2004 1000 EST West Chop 0.2nm West 1941 Pollack Rip Channel 1 Sep 2004 1000 0751 F 1056 2.2+ 01 34 + 01 50 1.3 0925 F 1246 2.9 059 1246 0925 0321 201 67 09251032 67 1139 67 1246 67 2.9F902.6059

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Slide 21 Exercise 8-2 Location: Waquoit Bay Entrance (Sub-Station 1926) Calculate speed & direction on 26 Aug 2004 1100 EST Waquoit Bay Entrance 1926 Pollack Rip Channel 26 Aug 2004 1100 0811 E 0536 1.4+ 04 01 + 03 40 0.8 1212 E 0916 1.1 203 1212 0916 0256 176 59 09161015 59 1114 59 1213 59 1.1E901.0203

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Slide 22 Exercise 8-3 Location: Southeast of Nobska Point (Sub-Station 1946) Calculate speed & direction on 24 Sep 2004 0100 EST Nobska Point 1946 Pollack Rip Channel 24 Sep 2004 0100 0210 F 2225 1.8+ 02 15 + 02 33 1.3 0425 F 0058 2.3 071 0425 0058 0327 207 69 00580207 69 0316 69 0425 69 0.0F0 ----

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Slide 23 Exercise 8-4 Location: 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 1946 Golden Gate Bridge 1 Sep 2004 1000 1122 F 0819 3.6+ 00 15 + 00 19 1.0 1137 F 0838 3.6 022 1137 0838 0259 179 60 08380938 60 1038 60 1138 60 3.6F501.8022

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Slide 24 Exercise 8-5 Location: Richardson Bay Entrance (Sub-Station 601) Calculate speed & direction on 26 Aug 2004 1100 PST Richardson Bay Entrance 1946 Golden Gate Bridge 26 Aug 2004 1100 1243 E 1507 1.0- 02 34 -03.06 0.3 1009 E 1201 0.3 225 1201 1009 0152 112 37 10091046 37 1123 37 1200 37 0.3F900.3225

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Slide 25 Exercise 8-6 Location: 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 1946 Golden Gate Bridge 24 Sep 2004 0100 2342 E 2000 2.2+ 01 50 + 01 33 0.5 0132 E 2133 1.1 192 0132 2133 0359 239 80 21332253 80 2413 80 0133 80 1.1F1001.1192

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Advanced Piloting Course (Coastal Navigation) Chapter 9 Piloting with Wind/Currents Educational Officer – Dave West dwest@voyager.net - 651-429-3840 Assistant Educational Officer – David Moberg davidmoberg@att.net – 715-386-8582 Instructor – Art Mollica artmollica@usfamily.net - 651-777-0277 United States Power Squadrons ®

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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

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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 1030 1130 1130 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 9.0 60D = ST S = 60 X 4.0 / 120 Dft = 2.0nm

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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

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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 = 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

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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

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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)

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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 = 75 min 60D = ST S = 60x6.6 / 75 S = 5.27 = 5.3kn C 029M S 6.8 T = 014 V = 15 W M = 029 1030 – 0945 = 45 min 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 COG 174M SOG 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

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Slide 34 Questions ? … Comments

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Slide 35 Finish Weekend Cruise Next Class – 24 May Homework

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