I use an 8mm line, about 4m long, tied AND TAPED around the dolphin striker. The key thing is, it's kept in a pocket that closes with velcro, and it's on the UNDERSIDE of my trampoline just behind the main beam. It's protected from wave bashing by the mainbeam itself and is instantly and easily accessible once the boat's gone over.

It also doesn't take long to stuff the line back in once the boat's 'pointy stick up'.