Used this to float foam under my bottom of my '88 Malibu ski boat. The thing is worth the money. Make sure the boat is at an angle so the product is rubbed into the cavity to be filled. Also note that you should test mixing in larger amounts for a smaller area first. See how much this material stretches in front of your hand. This puts pressure on the object being filled and can cause some bending if you add too much. But great product for the money.