I'd take the $30,000 and buy the boat back, When you are doing the repair with your own money, you can cut corners that you would not permit the insurance company to do. Consider replacing the rail only on the damaged side, with something that cosmetically matches the other side...only you are likely to notice the difference.
After the repair, if your existing insurance company has any reluctance to fully insure the boat (I wouldn't blame them...), get a clean survey and switch to another company. Does your state even have titles for boats...many don't...
A fellow at my club had a similar situation, he bought the boat back for $1000, and used the insurance proceeds for a professional repair, included a full awlgrip job of the topsides and a new set of sails, and ended up with a boat far more pristine than prior to the accident, and with money in the bank.
Certified...in several regards...