the water visibility was about 8-10 feet. The water did circulate, but not well... and in the summer time the temp went up to about 78 degrees. The water was fairly alive with critters such as fish and crabs.

These worms would attach to the hull and leave a crusty trail that was really hard to remove... took a good scraper like a plastic putty knife. The worms were sort of gelatinous and sort of clear... you could just sweep them away with your hand, until they established. They were heck on the knotmeter impeller. Just a royal pain to keep that wheel clean.

The pic below shows the crusty trail these things left as a sort of web. Imagine a spider web of a hard calcium sort of material covering parts of the bottom and the prop.