The big round clamp holds the bowl to the base. If it is loose it will leak. It pretty easy to take it apart.
1) Turn off the water pump
2) Disconnect the fresh water hose from the bowl.
3) Loosen the ring all the way and drop it down on the base, out of the way.
4) The bowl will now lift off.
5) Two rubber seals are there, either stuck to the bowl or the base.
6) They are different and different colors, remember the order
7) Inspect them, if they are not worn or ripped, clean them well with soap and water.

If worn or turn, buy new ones online.
9) Reassemble, should be OK
Get a new shrink wrap guy. Sloppy fit allows the wrap to rattle in the wind and scratch your gel coat. It shows worse on colored hulls. You need to buff them out. I'd look for a professional, if cleaner wax doesn't take them out.