I cannot swim but the rest of my family can. Will this be a problem?
Staying onboard a superyacht is perfectly safe for anyone who does not know how, or does not want, to swim.
If you do not fancy a dip in the ocean, there are lots of non water related activities to be had, and any shuttle to and from the shore will be done on tenders, without having to touch the water. Life jackets will always be provided ; so you really need not worry if you cannot swim.