On Mon, 09 Jun 2008 19:24:42 +0000, Larry wrote:

What I always thought we needed was a sort of underwater "curb feeler"
like we used to put on the pimpmobiles. A couple of stiff wires that
would protrude down into the water 3 ft from the BOW that would make an
awful griding noise

Such devices exist.

They are frequently called propellers.