My prindle 18 and trailer is covered by Auto Club. I also have a 1,000,000 liability add-on, which at one time was required for us to keep our boats on the beach by the County of L.A.
It's about $70 per year.

An uninsured driver ran off the road years ago and landed on my boat which was parked on the adjacent sand, just below grade level. Auto Club paid the full claim, no problem.

Sheldon