BoatSafe® Jr 300 WattPart #: JR-300WOur mid-sized marine bilge heater provides forced-air heat through a patented case design to keep your engine compartment safely above freezing. The Boatsafe® boat heater does this while maintaining ignition protection. When the boat heater's sensor detects an ambient temperature of approximately 45° Fahrenheit (7.2°C), it turns on and remains on until the engine compartment reaches approximately 55° Fahrenheit (12.7°C).Benefits of using Boatsafe® Marine Engine Compartment Heaters