I'm not sure about the multiplicities. That was never my strength.
From a design point of view, I might consider rearranging the bottom row to reduce the amount of line crossing, but that is based purely preference.
I do get tripped up by this part though:
North Marina also offers boat repair service which requires an owner to sign a contract with a company representative responsible for repair.
The details are a bit vague. Does the owner have any direct relationship with the representative (your diagram suggests no, and I sort of agree based on the lack of information)? But, more concerning, would the contract have some reference to either boat or agreement? I mean, a boat repair contract isn't very useful if there is no mention of what boat is being repaired...
I think, as is, your diagram is fine (unless someone says the multiplicities are wrong). I assume this is for school. If your professor takes off points because s/he intended on contract doing any of what I said, you should argue that the instructions were vague.