"Amanda" wrote in message
...

I have the opportunity to crew on a racing yacht as tactitician and
would like to learn more about racing with a GPS. Apart from the
obvious (distance and bearing to the next mark) what other uses can a
GPS be put to in yacht racing?

I've raced dinghies and cruised yachts so I'm familiar with general
tactics and how to use GPS, but I need to put the two together.

Jeff Richards wrote:

VMG - velocity made good towards a waypoint. That will tell you
whether pinching (and slowing) or freeing (for speed) will get you to
the windward mark quicker, or exactly what course on a downwind gybe
gets you to the lee mark quickest. You will need a 'relative bearing'
(angle off the bow, or pelorus) device to tell you when to tack or
gybe onto the equivalent course for the mark. You will need to get
all the marks as waypoints, so this may mean visiting each mark and
entering the waypoint before the start.

If you can link the GPS to boat speed and direction then it can
calculate tide set and rate, or you can do it manually if they can't
be electronically connected.

The other useful feature is to be able to save the course sailed for
later analysis, but general purpose GPS software doesn't usually
provide decent analysis tools, so you may have to write your own. You
should be able to replay the whole race or selected parts,
identifying where you gained or lost ground and perhaps working out
why.

How do you mean, Jeff? I find that Maptech, etc., make this pretty clear. With
my path drawn on the screen, I can see exactly what was going on, where I gained
or lost ground, etc., better than ever before. A picture is worth a thousand
spreadsheets!

PC-based navigation programs all have their warts. In fact most of them are
pretty bad in one way or another. But for the most part they do a good job
telling you what you need to know.

However, I'm not familiar with the software/firmware in most self-contained GPS
units.

Matt O.