I've used it for gluing laminated paddle blanks and adding material to the gunwales on skin on frame boats. It's waterproof and very strong when used properly. While it will expand to fill gaps, the resulting foamy glue is very weak. It's also rather thick and slippery, which can lead to pieces moving in relation to each other. For these reasons, it should be clamp firmly, so that the glue cannot expand (except outside of the joint) and the parts cannot shift.