M-rating

Source: John Deere Marine Engine Pocket Guide / Marine Applications, Diesel Engine Ratings.

M1

The M1 rating is for marine propulsion applications that may operate up to 24 hours per day at uninterrupted full power. These applications typically operate more than 3,000 hours per year and have load factors* over 65 percent. The M1 rating is the ISO 8665 standard power rating and the SAE J1228 crankshaft power rating. Both are defined as the power level at which an engine can run continuously between recommended service intervals. Possible applications: Line haul tugs and towboats, fish and shrimp trawlers/draggers, and displacement hull fishing boats over 18 m (60 ft).

M2

The M2 rating is for marine propulsion applications that operate up to 3,000 hours per year and have load factors* up to 65 percent. This rating is for applications that are in continuous use, and use full power for no more than 16 hours out of each 24 hours of operation. The remaining time of operation must be at cruising† speeds. Possible applications: Short-range tugs and towboats, long-range ferryboats, large passenger vessels, and offshore displacement hull fishing boats under 18 m (60 ft). Marine auxiliary power engines for dedicated hydraulic pump drives, dredge pumps, or other constant-load marine applications should use the M2 rating.

• Load factor is the actual fuel burned over a period of time divided by the full-power

fuel consumption for the same period of time. For example, if an engine burns 160 liters of fuel during an eight-hour run, and the full-power fuel consumption is 60 liters per hour, the load factor is 160 liters / (60 liters per hour x 8 hours) = 33.3 percent. † Cruising is any operating time where the engine speed is more than 200 rpm less than the maximum attainable engine speed.

M3

The M3 rating is for marine propulsion applications that operate up to 2,000 hours per year and have load factors* up to 50 percent. This rating is for applications that use full power for no more than four hours out of each 12 hours of operation. The remaining time of operation must be at cruising† speeds. Possible applications: Coastal fishing boats, offshore crew boats, research boats, short-range ferryboats, and dinner cruise boats.

M4

The M4 rating is for marine propulsion applications that operate up to 800 hours per year and have load factors* below 40 percent. This rating is for applications that use full power for no more than one hour out of each 12 hours of operation. The remaining time of operation must be at cruising† speeds. Possible applications: Inshore crew boats, charter fishing boats, pilot boats, dive boats, and planing hull commercial fishing boats.

M5

The M5 rating is for marine recreational propulsion applications that operate 300 hours or less per year and have load factors* below 35 percent. This rating is for applications that use full power for no more than 30 minutes out of each eight hours and cruising† speed the remainder of the eight hours, and do not operate for the remaining 16 hours of the day. Possible applications: Recreational boats in the U.S., tactical military vessels, and rescue boats outside the U.S.