Wayne. B wrote:

The de-icer you describe works by bringing warmer water up from the
bottom. It will work OK as long as the water is deep enough to have
a
decent temperature gradient; you have enough units to cover the area
in question; and you have a reliable source of power.

Thanks Wayne
the water will only be about 2 feet to 3 feet at low tide depending on
which end of the dock that you are at, at high tide it may be another 6
feet. I was under the impression that it stirred up the water and
moving water would not freeze. I did not relize that it was going to
depend on the water's depth. Thanks for the info.
Anyone have any ideas?