Charlie Morgan wrote:
On Wed, 21 Feb 2007 12:26:28 -0500, katy
wrote:


Wilbur Hubbard wrote:

"Shaun Van Poecke" wrote in message ...


"Wilbur Hubbard" wrote in message ...


When you estimate leeway you end up plotting it on a chart, don't you?
That should tell you something. On a chart there's no apparent wind
and there's no apparent current. There is only true wind and true
current as it applies to the chart.

If you used apparent wind/current you'd have to extrapolate to true
prior to placing yourself on the chart. So why bother?

Leeway is a function of true wind and current when it comes to plotting
your position on a chart. Apparent is totally meaningless because you
have to ask yourself the burning question: apparent to what? Your ship,
of course. What you feel from the deck of your ship means nothing
as concerns your geographical position (GP)


Wilbur Hubbard

Im not so sure about that... leeway can be estimated on many levels.... the fellow out in a motor dinghy, another guy
out in a sailing dinghy, and the person out in a larger yacht with navigation instruments on board. estimating leeway
in a harbour is entirely a different matter from estimating it in the open ocean. leeway is also something that
varies a lot with the type of vessel.

I know when im out sailing in sydney harbour on my beach cat, i suffer leeway a lot, but i can eye it in off a
landmark to allow for my course. I know in relaity i will be lucky to end up with a course made good within 30
degrees of what i was helming for!

Out on my 26 foot keeler leeway is a lot less, but on a longer trip.... it sure can add up to a lot! If im out of
sight of land it gets to be impossible for me to estimate in my head and then its time to compare on a chart my GPS
course vs. compass steered course. It would take a very experienced and/or lucky person to be able to estimate leeway
on a vessel they were unfamiliar with in waters that were unknown to them.

Shaun


Over here in the U.S.A. we have something called waasGPS. It's a great invention.
It's accurate to within inches. You set a course to where you wish to arrive at.
Then you follow the compass course on the screen on the GPS. But if you have
any leeway, drift or set the GPS comes up with something called cross-track error
and it tells you which way to steer to get back on course. The cross-track error is
a combination of set, drift and leeway. It's not possible to tell them apart. It's a
combination figure only. What matters is you know your position on the chart and
you've corrected for any and all deviations from the course line. So, and I hate to
say it, Milton Waddams is asking a silly question. The people who are trying to sound
like some kind of authority figures are making fools out of themselves.

Wilbur Hubbard





And then the satellite gets shot out of the sky when you're in the
middle of the Gulf Stream....


All 30 of them?

CWM

Just the one you're using...or 2 or 3 or whatever...the point, so
obviously missed by your limited mind, is that GPS systems rely on other
devices that could prove unreliable...or unavailable...