There are two main parts to marine insurance policies – the physical damage coverage and the liability coverage. These two parts are really important when discussing coverage for trailering your boat. Generally, marine policies will cover physical damage to the boat while trailering, but not liability because liability comes from the auto policy. Why? The trailer isn’t under it’s own power, it’s movement is controlled by the car. For example, if while turning a corner your trailer side-swipes a car, the liability for the damage to the third party’s car would be covered by your auto policy. As another example, your boat wasn’t secured properly on the trailer and you turn the same corner. Your boat rolls off the trailer, landing in the ditch. This is a physical damage loss – your marine insurance policy would cover the damage to the boat.