Jet Boat Autopilot
On Sun, 30 Nov 2003 09:49:02 +1030, BruceM wrote:
Sorry I don't know the construction history of "drunkboat" but I'm sure that
everything is still as it was when constructed. The problem is not so much
with the auto pilot as it is to do with the jet.
Have you ever let a high pressure hose go seen how it goes back & forth?
The effect on the last foot of hose is determined on the direction the hose
was pointing milliseconds before, not where it's pointing now.
The effect on the boat is IDENTICAL to what happens to the hose. Of course
steering by hand you tend to anticipate the "direction of thrust" & can
counteract BEFORE it happens. (if you are on the ball)
The auto pilot only reacts after it is determined that it is offcourse &
also off by a certain amount off course. In other words, much too late.
There might be a brand that can be set with quicker react time or something,
but I'm not sure.
I guess after all is said & done that if you got given one for Chrissy, then
I'd still put it on your boat. Just don't expect it to go "as the crow
flies" as us Aussies say.
BruceM
Thanks, Bruce,
I recall from years ago that handling large craft was very much the same
thing: you applied rudder and the reaction was delayed. Stopping was
similar - you approached slowly and with caution and reversed engines well
before you wanted to stop. All of this is what I generically call
"damping" - anticipation of the effect and a delayed reaction to change.
Now my experience with autopilots is practically nil - the only time I used
one was very brief and basically it just kept the boat on course. I had
hoped that when you set up an autopilot, that you could trim the amount of
steerage. Are you saying that you can't?
Best,
--
Larry
email is rapp at lmr dot com
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