What to wear for company party on a boat?

(F28) The company my husband works for is having a mid day party, on a boat (at a yacht club). His job requires a uniform but Id say the office workers dress business casual? I have to take my shoes off on the boat. Itll be 80 degrees.

That's about all the info I have. What would you wear? I was thinking a casual sundress but im worried it will be too windy.