RedactedNarrative: Vessel 1 was heading back into harbor in fairway. Operator of vessel 1 as turning to enter slip, the wind carried the stern in the opposite direction. Vessel 1 swim platform (port side) collided with vessel 2 which was in the slip unoccupied on the portside of that swim platform. Vessel 1 sustained a crack in the fiberglass and no visible damage to vessel 2. Witness of vessel 1 tried to prevent the accident but wasn't successful. The owner of vessel 2 was on the dock covering the vessel 2 and witnessed the accident. No injuries.