Engine Types
Before selecting an engine, first check the rating that applies to your application to ensure that you select the most appropriate engine for your requirements.
"A" CONTINUOUS
"A" ratings are for heavy duty service in ocean-going displacement hulls such as freighters, tugboats, bottom drag trawlers, and deep river towboats when the engine is operated at rated load and speed up to 100% of the time without interruption or load cycling.
For 3600 engines only: Continuous Service Rating is suitable for continuous duty applications, including dredges, for operation without interruption or load cycling. Maximum Continuous Rating is generally used for vessel applications involving varying loads. The engine power actually produced is limited by application guidelines, leaving a power reserve for unusual operating conditions. - Load factor: 80% to 100% time at rated rpm
- Typical hours/year: 5000 - 8000
"B" MEDIUM DUTY
"B" ratings are for displacement hull vessels such as mid-water trawlers, purse seiners, crew and supply boats, ferries and towboats where locks, sandbars, and curves dictate frequent slowing and engine load and speed are constant with some cycling.
- Load factor: 40% to 80%. Up to 80% time at rated rpm
- Typical time at full load: 10 hours out of 12
- Typical hours/year: 3000 - 5000
"C" INTERMITTENT
"C" ratings are for planing hull vessels such as ferries, fishing boats moving at higher speeds out and back, off-shore service boats and displacement hull yachts, and short trip coastal freighters where engine load and speed are cyclical. Chp - Fast commercial and passenger vessels and cruising yachts with moderate load factors.
- Load factor: 20% to 80%. Up to 50% time at rated rpm
- Typical time at full load: 6 hours our of 12
"D" PATROL CRAFT
"D" rating typical application: Planing hull vessels such as off-shore patrol boats, customs, police and some fire and fishing boats. Also used for bow and stern thrusters.
Dhp - Patrol craft, fast passenger vessels and cruising yachts with low load factors ( 2 out of 12 hours).
Military Fast Vessel Ratings - (3612, 3616) For patrol craft and other naval vessels with low load factors. - Load factor: Up to 50%. Up to 16% time at rated rpm
- Typical time at full load: 2 hours out of 12
- Typical hours/year: 1000 - 3000
"E" HIGH PERFORMANCE
"E" rating typical applications: Planing hull vessels such as pleasure craft, harbor patrol, harbor master and some fishing and pilot boats.
Ehp - Fast patrol craft and fast yachts with low load factors (1/2 hour out of 6).
- Load factor: Up to 30%. Up to 8% time at rated rpm
- Typical time at full load: 1/2 hour out of 6
- Typical hours/year: 250 to 1000
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