RedactedNarrative: Vessel has a Penta Volvo forward drive engine with dual propellers. Vessel hit a rock near Bird Island going an estimated 10 MPH. Speed was estimated by one of the passengers. There were no injuries due to the collision, but the vessel began to take on water. Vessel was towed back to Provo Marina and loaded onto the trailer. Upon being pulled from the water to look for damage, it was noted that there was damage to the first propeller, but the rear propeller looked to be ok. There was also damage to the skeg where it appears to have drug across the object that was hit. There was no fiberglass damage that was seen. It is beleived the engine seal broke, and that is where the water was entering the vessel from. Passenger also mentioned the engine did not sound right when they tried to restart, and that the engine had got very hot. Possible impeller damage done.