On Mon, 05 Mar 2007 07:20:39 +0100, BrianH wrote:

Matt O'Toole wrote:
On Fri, 02 Mar 2007 08:05:53 -0500, Roger Long wrote:

Shaun Van Poecke wrote:

If the waves are big enough to worry about this, the
real issue is breaking waves. Any time you are in
water less than about twice the depth of the average
size waves going by, there is the possibility of one of
the few largest waves of the day breaking on that spot.
If you think a wave twice the size of the average
breaking hard on your boat would create more excitement
than you care to deal with, you should keep at least
twice the average wave height under your keel and a
little more when passing over isolated ledges.

Shallow water may cause steep waves, but prevents them
from building beyond a certain point. So you don't have
to worry about the occasional huge wave in shallow water
like you do in the open ocean.

"You don't have to worry"??? Last summer in the entrance to
Laguna di Marano, northern Italy, a returning professional
fishing boat was slewed and rolled by an extra large
breaking wave and dropped on the bottom while inverted,
smashing in the wheelhouse and killing two men. A third, who
was on deck, was thrown in the sea and survived.

Well of course waves breaking as they hit shallow water, such as when they
hit a bar, is a big problem! But then the energy dissipates, and large
expanses of shallow water cannot carry big waves.

Matt O.