One important feature to insist on, is "agree value". This should be the real value of the boat--what it will cost to replace, including accessories and electronics. For example when I put new electronics etc on the boat, it increases the replacement cost. I call my agent, tell why and they will increase the value.
I never will understand why people insure the boat for a fraction of value, thinking that nothing will every happen to them which will cost more than XX dollars. Insurance is for the unthinkable. This brings to mind the several sailboats whose loss was discussed in another thread. At least one of them was insured for only 1/3 of the value. Also in that case, the owner had gone was a less than well known insurance company which went out of business, because of a high number of claims. I remember this, because Seven Seas Cruising Association when I was on the Board of Directors was always looking for "Affordable" long distance cruising insurance....a good policy is expensive, for very good reasons!