If you want to take someone sailing on a boat and you ask them if they can swim, what exactly are you asking? Everyone can float if they have a life jacket right?
My understanding is that someone is being asked if they can take care of themselves and/or tread water until they are rescued and/or if they are a strong swimmer, but I could be wrong.
I think the implication is that they want to know if you can swim.
Floating doesn’t mean not panicking
Yeah, plus being able to swim means being able to maneuver with the lifejacket on in addition to basic water safety knowledge. Being able to maneuver a short distance with a life jacket makes getting back on the boat s lot easier.