Hello. I have seen this problem before on RV rubber roofs. It tends to be vultures that do the damage. Where is the boat located? If it's Indiana or a neighboring state it is probably turkey vultures. The RV's I've seen damaged were from Vultures in Arizona. I've read many studies on vultures and rubber/vinyl damage and there is no conclusive reason why they attack the rubber. The old theory was that the oils and or fats used in the production would emit an odor in extreme heat however that doesn't seem to be a solid theory as vultures have a horrible sense of smell and are usually visual scavengers. Can you please have your neighbor send me a DM and I will see if there is anything we can do to help them at Godfrey?