The image that everyone in the US sues is overblown. It's more frequent than in many countries but I've managed to live in the US for over 50 years, owned six boats, 12 cars, three homes and four businesses (not at the same time) and never had to sue or been sued on a personal basis. A few threats both ways but it was always figured out short of court.
Since you've got insurance - I assume from a good company and a fairly complete policy - I'd let them handle it. It's their business. My policy from Markel has coverage for "uninsured watercraft". I assume most do.
You were tied to a dock
and he wasn't and there are law enforcement reports -- this isn't a very difficult case to sort out blame.
Your insurance company will to after the other boat's insurance company or if he doesn't have any they'll go after him.
The only trick I've learned with insurance companies is to not assume anything and to over communicate (in a nice way). I ask questions and check in every few days until I get a check.