I disagree that they are worthless on a catamaran. They are if you think of them as something you throw as speed along as somebody fell off. But consider bad conditions and how tough it is to get your boat close enough to somebody so they don't have to swim. For the cases where it is tough to get that close, loop back to the COB, park then throw the throwable with a line attached. You won't need to drive close enough to hit/scare them...