Just tell him to be patient and enjoy the game. I had friends leave just because they couldn’t spawn a rowboat or get on my brig, hopefully, your friend lasts a little longer. His patience will pay off.
If he’s impatient then I think fishing would at least be a good way to pass the time while sailing, even if you can only catch 1 or 2 fish while your friend is driving a high speed boat to the next island