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That's why I like waypoints connected by route lines.  On a longer crossing,
I watch the tide, wind, compass heading and GPS chartplotter route line.  I
estimate the heading I need to steer to correct for leeway and current, then
follow that for a while.  If the GPS trackline starts to fall off the route
line, then I correct the heading appropriately.  This method allows me to
stay fairly close to the route line, without having to make large
corrections.  I end up following a course that approximates the route line
fairly well.

See this page for some screenshots of the process I follow, which I think is
a fairly efficient compromise.  In fact I doubt that I could do better if I
tried to do the formal DR process, including calculating leeway and current
vectors to derive headings.
http://jimthompson.net/boating/Steering.htm

Jim Thompson
jim2@jimthompson.net
www.jimthompson.net
Outgoing mail scanned by Norton Antivirus
-----------------------------------------

> -----Original Message-----
> From: Navigation Mailing List
> [mailto:NAVIGATION-L@LISTSERV.WEBKAHUNA.COM]On Behalf Of George Huxtable

> If the vessel was following a ground-track using GPS, waypoints would be
> set at A and B, and a straight-line ground track drawn between them. The
> helmsman would be commanded to steer West of South during the
> first 6 hours
> to keep to that track and counteract the tide, and then, later, East of
> South, to do the same. In the case of a slow vessel, and a hot tide, the
> attempt to keep to the straight track may even become impossible. But in
> any case, those Eastings and Westings are quite counterproductive,
> cancelling each other out, and are made at the expense of the Southing,
> which in this case is all that matters. Sceptics may find that a simple
> vector diagram will convince them, but are welcome to argue back if it
> doesn't.

   

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