There are two important covers to consider when insuring your boat. They are, Hull & Machinery (your boat and attached equipment) and Liability.
You should insure your boat (hull & machinery) to the current market value. This will ensure that in the event of a total loss to your boat, you will recover what the boat is worth.
Liability coverage protects you if you are at fault for property damage and bodily injury claims to third parties or passengers in your boat . The coverage has three key components. It will investigate your loss, defend you if you are not at fault and pay up to the policy limit if you are at fault.