RedactedNarrative: The owner of Sebago Lake Cottages reported that one of his rental boats had been involved in a crash. The operator of the vessel (V1) was operating on Sebago Lake. The water was rough and he was unfamiliar with the lake. Operator 1 tried to stay closer to shore and struck some submerged rocks doing damage to one of the boats pontoons and the lower unit of the outboard. One of the passengers in the boat complained that the rocks were not marked causing an unsafe condition.