I also spoke to John at Total Dollar Insurance, a Markel rep, and he said Markel has horsepower limits that they will insure, twin 575's for 32', twin 700's for 36'. Over that it is considered "over powered". He also said for similar sized boats, similar value, and similar top speeds, the cat insurance is approximately three times more expensive than a V. He cited a higher incident rate, and higher loss levels per incident for cats vs. V's. As an example, I asked about two boats both worth $100K and capable of 110 mph. The V "ballpark" (don't hold him to it) was $1800, while the Cat was $4.5K to $5K.
Also their policies state that if alcohol is found to be involved, the claim will automatically be denied. He mentioned that one of his customers doesn't allow drinking by ANYONE on the boat until the boat ride is over, in case he needs that person to be an eyewitness or help out after a crash.