On 24 Jan 2005 20:06:41 -0800, "richard"
wrote:

I was under the impression that it stirred up the water and
moving water would not freeze.

=================================

That's part of it but the big thing is bringing warmer water to the
surface. You have shallow water but a big tide range so it's hard to
predict just how it will work out. If the weather is cold enough,
frozen pilings are a real problem. I've heard stories of using chain
saws at low tide to free the ice.