We had to demonstrate (i.e. paperwork) that we had at least $SOMANYDOLLARS policy on our boat at the NAF18 North Americans. The Tybee 500 also requires you to demonstrate an insurance policy.
The insurance company will readily provide you a document showing what your coverage and limitations are...usually a one page sheet. With my company I can print it online. My insurance is a replacement policy (i.e. if I can't find a 2004 Nacra F18, they will cover the expense for the next newest boat I can find or new). It also covers me if I were to charter another boat for an event. They cover it while trailering and cover me if I foul someone resulting in damage or personal harm up to a limit. They also reduce my $500 deductable by 25% (to $0 in four years) each year that I don't have a claim. All for $181 a year.