Patent ID: 8864538

Claim:
A method for cooling a marine propulsion system on a marine vessel, the method comprising pumping with a lift pump raw cooling water from a body of water in which the marine vessel is situated through an open cooling circuit from an upstream inlet for receiving the raw cooling water to a downstream outlet for discharging the raw cooling water back to the body of water; indicating with at least one sensing device whether the lift pump is connected to the body of water, wherein the sensing device is in communication with a control circuit; and preventing with the control circuit operation of the lift pump when the sensing device indicates that the lift pump is not connected to the body of water; wherein the at least one sensing device comprises a depth transducer disposed on a hull of the marine vessel, and further comprising determining with the control circuit that the lift pump is not connected to the body of water when the depth transducer does not indicate a water depth reading.