There are two movies I'm trying to find the names of...
I probably say they could be around 1986 vintage at a guess.
First one, focuses about a group on a yacht, but one of them enjoys s*ex and likes to look after all the women on board. His signature move was to use his knife from his ankle holster and slice the skinny part of the biking off whoever he's looking after. I remember some suspense as you were concerned that he was going to stab the woman but doesn't.
Second one involves a family
on a yacht abandoning ship and spending time in a life raft. I recall
that they caught and ate a turtle and got sick from it and they also had a submarine pass underneath them.
Any suggestions welcome!