Correction for Leeway - Coastal Navigation Question - Page 3 - SailNet Community
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post #21 of 24 Old 07-31-2011
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I thinkthat JRD is probably correct and the OP is trying for a captains license or taking Coastal Nav from ASA which is I think more difficult. It is all fine to suggest that he just look at it or use his GPS, but that does not answer his question.

Leeway and current set can be calculated. I suggest Pyzel's Coastal Navigation book which is used for ASA. I took the course but lent the book to someone and have never gotten it back. I admit that I do just look at it and use my GPS, but also keep paper charts and plot for the practice. I just don't worry about Leeway or set as usually my next mark is not more than 50 miles away.
OP, know that there are some incorrect answers in both Pyzel and the USCG books, as well as many of the ASA books.
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post #22 of 24 Old 07-31-2011 Thread Starter
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Hi All,

Thanks so much for your help. This question is actually from a home study workbook from a sailing school in the West Coast (SF Bay Area) for a U.S. Sailing Coastal Navigation certification. The problem is written by the school.

The problem states that "the winds are west at 22 knots when you depart point A at 1530 assuming a leeway of 4 degrees and a boat speed of 6 knots.

The variation on the chart is 14 degrees East. There is no mention of deviation.
The track from A to B is 145 degrees magnetic.

My assumption (correct me if I'm wrong) is the wind is coming from the WEST as opposed to from the EAST.

Let me add more information, if this helps. From the Current Tables, current velocity is 3.48 Ebb, and Ebb direction is 266 degrees TRUE.

Does this help? Thanks.
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post #23 of 24 Old 07-31-2011
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Let me add more information, if this helps. From the Current Tables, current velocity is 3.48 Ebb, and Ebb direction is 266 degrees TRUE.

Does this help? Thanks.[/QUOTE]


Well...yeah, Information regarding a 3.5 kn current would have been useful.

Any more rabbits in the hat?

So this is a compound problem... Set and Drift... and Leeway.

You need to compute the course to steer using the set and drift.... This is where your, time, distance and speed now become a factor....

Then apply the leeway... after.... you figure out the CST from the set and drift problem

Good luck...

Don't forget to use TVMDC..to go from true to mag..or visa versa..

Normally when I see these course books...they give you a deviation table to work with too...keep looking..I'll bet you it's there somewhere.

here's a you tube video for ya ... he could have done this a little better..but you get the idea.


Tempest
Sabre 34
Morgan, NJ

Last edited by Tempest; 07-31-2011 at 06:22 PM.
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post #24 of 24 Old 08-03-2011 Thread Starter
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Thank you everyone for taking the time to reply. It all make sense to me now.
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