I don't have a hoist for my boat because the harbor that I keep it in can get too shallow, so it sits in the water all spring, summer, and fall. Getting the algae off is very difficult and I usually end up using a hydrochloric acid-based product that can burn your skin, eyes, lungs, and just about anything else it gets on. I bought a couple of these recently and used on the parts of my hull I can get to while the boat is in the water. Lo and behold, it easily removes the algae completely without much effort. I would highly recommend this product, especially since the cost is so low. The only improvement would be to make it float. It sinks very slowly so this is not a big deal.