One simple but effective precaution is to mark the toe rail directly above the propeller and not going more than a foot or so below the water line when scrubbing that part. The waterline can of course be cleaned all the way to the transom. This is a good idea as you can then clean around the propeller as the propeller will not be turning. Subscrub works on Hydrodynamics so must have water moving past it, in order to function. Subscrub works at speeds between 2 and 5 knots.
Slow speeds give a gentle scrub, faster speeds a stronger scrub.
Click graph on right to see larger version. Click on graph for larger size. Try scrubbing horizontally instead of vertically if necessary. If your question is not answered here, send us an e-mail and we will be pleased to answer your question. Subscrub - Worldwide Patent applied for.