42374F 6 Mercury COVER, MOUNT (BLACK)

Rating Definitions
It is important to know how the boat will be operating, so the rating can match the operating profile. Additionally, proper rating selection is important so that customer perception of price/value is realized.In selecting a rating for a specific application, the most important consideration is time spent at full throttle. These rating definitions identify percent of time at full throttle and corresponding times below rated rpm. A (Continuous): For heavy-duty service in ocean-going displacement hull vessels such as freighters, tugboats, bottom drag trawlers, and deep river towboats when the engine is operated at rated load and speed up to 100 percent of the time without interruption or load cycling. Typical use is 5,000 to 8,000 hours per year. B (Medium Duty): 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 when engine load and speed are constant with some cycling. The engine may be operated up to 80 percent load factor and at rated load and speed for up to 80 percent of the duty cycle, or 10 hours out of every 12 hours. Typical use is 3,000 to 5,000 hours per year. C (Intermittent): For planing hull vessels such as ferries, fishing boats moving at higher speeds out and back (i.e. lobster, crayfish and tuna) offshore service boats, and also displacement hull yachts and short trip coastal freighters where engine load and speed are cyclical. The engine may be operated at up to 80 percent load factor and at rated load and speed for up to 50 percent of the duty cycle, or 6 hours out of every 12 hours. Typical use is 2,000 to 4,000 hours per year. D (Patrol Craft): For planing hull vessels such as offshore patrol boats, customs, police, and some fire and fishing boats. Also used for bow and stern thursters. The engine may be operated at up to 50 percent load factor and at rated load and speed for up to 16 percent of the duty cycle or 2 hours out of every 12 hours. Typical use is 1,000 to 3000 hours per year. E (High Performance): For planing hull vessels such as pleasure craft, harbor patrol, harbor master, and some fishing and pilot boats. The engine may be operated at up to 30 percent load factor and at rated load and speed for up to 8 percent of the duty cycle or 1/2 hour out of every 6 hours. Typical use is 250 to 1,000 hours per year.The above rating definitions assure the customer obtains an acceptable and competitively priced match between initial cost and total life and lifetime costs.When operating the engine in an application consistently requiring more time at full throttle than the designated level, higher maintenance costs and premature wear of the engine will be encountered.
Operating engines above the rating definitions will result in shorter service life before overhaul.
For most applications, the customer can provide profile information from similar vessels or the actual vessel, if repowering. If such information does not sufficiently indicate the operating profile, instruments are available to more precisely define engine operation. A 7D-1513 Tachograph Group can establish an operating profile. The tachograph records engine speeds versus time on a paper chart.Marine Classification Society Certification Requirements
The major seafaring nations have established technical groups called marine classification societies. Caterpillar has established and maintained product standards and factory quality under the guidelines set forth by the eleven major marine classification societies listed below. For more information, refer to LEKM1428, Marine Power Systems- General.* ABS = American Bureau of Shipping (U.S.A.)* BV = Bureau Veritas (France)* CCG = Canadian Coast Guard (Canada, formerly CBSI)* DnV = Det norske Veritas (Norway)* GL = Germanischer Lloyd (Germany)* KR = Korean Register of Shipping (Korea)* LR = Lloyd's Register of Shipping (Great Britain)* NK = Nippon Kaiji Kyokai (Japan)* RINa = Registro Italiano Navale (Italy)* RS = Register of Shipping (Russia)* ZC = Zhong Chuan (China)