G There is a simplistic explanation I've been given which may or may
not be entirely correct, so I'll skip it. However, two points to keep in
mind when under this condition.....
Reduce power.... this will reduce the strain on engines and boat and
even give back some of that speed lost while you sat there at full
throttle, digging a hole.
Watch your wakes, Port and Stbd. If they start to move from a their
normal trailing position to 90 deg off the side, your running out of
water .... this is particularly useful in channels as an aid to stay in
the channel .. i.e. .. if the wake on the stbd side moves up toward 90
deg and the wake on the port side trails normally, move to port. You're
getting too close to the Stbd bank.

otn

Dean wrote:

For the same reason a wave breaks when it nears shore. Your bow wave
is in ground effect, and encounters more resistance....

On Sat, 26 Jul 2003 21:23:48 GMT, Pete Drez
wrote:


I have a trawler that draws 5 feet of water. Nornal cruising speed is
8.5 knots, with 10 feet of water or more under the keel. As the depth
under the keel decreases the speed starts to slow, down to about 7
knots when there is 3 to 4 feet under the keel.

I have heard that boats will slow in shallow water and am interested
in the physics of why this happens. I would appreciate a link to
information on this subject or an explanation of it if someone
understand the subject.

Thanks

Pete Drez


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