It doesn't stay on except in the crevices for set screw holes etc. It does keep the holes clear, but hardly worth it. Perhaps it might be effective if you dive on the prop and wipe/reapply weekly, but that's about as practical as enclosing the prop in a plastic bag (which is also reputed to be effective). The bag or the Desitin might be a solution for people who leave their boat where the water is clear clean and warm, but not practical for me.