I'm insured (auto) with the company that drives the white explorers with their blue letters all down the side, yet they tell me they will not write a policy for a "high performance" catamaran (or any cat for that matter)

I'm a college student with a lot to lose if I hurt someone. Someone help me find insurance (State Farm wants an auto policy, which costs DOUBLE what mine does now)
I'm in FL btw.

Any help would be appriciated GREATLY!