I tried it on an old plank that was floating in the sea. Didn't work too well.

I also found a hydrofoil board floating in the surf on time, I dragged it in to the beach and left it for a while. After half an hour no one had claimed it so I thought I'd have a go and see what it was like. Someone came and claimed it and shouted at me

A boogie board, a jetski, a large wooden palette. Take your pick.

ironing board - bottle was because it sinks - fast!