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Obviously, the power passagemaker depends entirely on its engine for propulsion, and a great amount of attention must be paid to selecting, installing and maintaining the power plant. The marine diesel engine has proven to be one of the world's most dependable machines ever made, and today's new diesels are better and more reliable than ever.
Because of the great reliability of these engines, the many advantages of a single engine installation usually outweigh the desire to have a twin engine boat. Greater economy and reduced noise and vibration are the most obvious benefits. But single engine boats also handle better in rough conditions, especially when running off the wind, due to the prop blast against a large rudder. The propeller and shaft of single engine boats are also more protected from damage caused by hitting submerged objects or running aground. And, of course, maintenance is half of what a twin engine installation requires. Most Nordhavns are ordered with a single main engine plus a smaller wing engine for "get home" power, although twin engines have been installed on some models at the owner's request.
Because of the inherent efficiency of a displacement hull, the amount of horsepower required to drive the boat at hull speed is far less than what typical "trawler-like" semi-displacement boats require. When specifying horsepower, P.A.E. also uses the far more conservative, "continuous rating" figure provided by the engine manufacturer, which is often half of what other boat builders will claim for the same engine. Be sure to compare horsepower ratings carefully, and remember that full displacement hulls require far less power than other types of hull designs. All Nordhavn designs call for extremely reliable and durable engines built to run for virtually weeks-on-end and to be serviceable worldwide. Large, slow-turning props are best, so P.A.E. specifies 3-to-l gear ratios. All engines are de-rated to ensure trouble-free, continuous use. In order to further reduce noise, wear and vibration, engines that develop their rated horsepower at low RPM are specified.
Owners sometimes have specific engine preferences, and because P.A.E. provides custom capabilities, it is able to accommodate the requests. Caterpillar, Cummins, Lugger, Mann, and Yanmar diesels have all been successfully installed on Nordhavns.
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