91251-935-004 Water (17mm) Seal - Overview. The 91251-935-004 Water (17mm) Seal is a critical OEM component manufactured to support Honda marine engine systems, specifically designed to fit a 17mm propeller shaft. This seal plays a vital role in preventing water from entering the engine housing and protects internal mechanical parts from water damage, thereby ensuring optimal operation and reliability of your marine engine. With its precise dimensions and perfect adherence to Honda's stringent f