Choices like engine brand are personal. We didn’t make a Deere vs Lugger decision on our Nordhavn 52—we would have been happy with either. Although the high quality support offered by Lugger clearly is important, the reason why 5263 will have a John Deere main is that we wanted a little bit more power and Lugger didn’t produce one that would fit.
The Nordhavn 52 is a longer, heavier version of the Nordhavn 47, and we had heard from many Nordhavn 47 owners “wonderful boat, but I wish it was just a little faster.” This is not a universal sentiment. Many hold the opposite view and argue that the boats would be better with less power. Nonetheless, many owners I respect wanted more speed, and this influenced our decision.
The arguments against higher horsepower include greater fuel consumption, increased engine weight and the risk of engine underload. What folks sometimes don’t understand is that a 265 HP engine operating at 150 HP will consume very nearly the same fuel as a similarly designed engine rated at 165 HP also operating at 150 HP. Fuel consumption is driven by the horsepower produced, rather than the engine’s rated horsepower. And in this case, engine weight is not a factor. The Lugger 1066T.2 that is standard with the Nordhavn 47 and 52 is a marinized John Deere 6068—the same engine series that we are installing.
Some folks agree that a higher horsepower engine occasionally would be nice for increased speed, but argue that the additional horsepower rarely would be used. As a consequent, the main would spend much of its life very lightly loaded. There is no question that engines need to be run at the designed operating temperature to reach full life. My experience with 4,000 hours on my current Cummins engines is that engines can be operated at very low HP outputs while still maintaining proper operating temperature. This, however, is a hotly debated topic. Personally, given the choice of 1) not having the power to achieve a speed-length ratio of at least 1.34 or 2) being able to achieve 1.34 but with the engines often operated at a lighter load, I prefer the second camp. And, I’ve seen more engines damaged by overload than under. But I don’t discount the concern entirely. Boating is full of compromises and tough decisions.
In thinking through whether the 52 needed more horsepower, we calculated horsepower per thousand pounds across the Nordhavn fleet:
• N40: 3.30 (50,000 lb @ 165 HP)
• N43: 2.75 (60,000 lb @ 165 HP)
• N43: 1.75 (60,000 lb @ 105 HP original engine)
• N46: 1.75 (60,000 lb FD @ 105 HP)
• N47: 1.94 (85,000 lb FD @ 165 HP)
• N50: 3.75 (80,000 lb FD @ 300 HP)
• N55: 2.66 (124,500 lb FD @ 330 HP)
• N57: 2.66 (122,000 lb FD @ 325 HP)
• N62: 2.19 (155,000 lb FD @ 340 HP)
Note: Weights are based on published specs at the time we did the calculations. Some are full load (FD), others are ambiguous. It’s rare, however, that any boat weighs exactly what a manufacturer claims.
With the extended cockpit and flybridge, not to mention all the equipment we planned to install, the 52 would be a heavier boat that the 47. If we assume it would weigh 100,000 lbs fully loaded, the standard 165 HP would be make it the lowest powered boat in the fleet with a ratio of only 1.65 HP/1000 lbs. I’ve been on the original 43 with only 105 HP, and did not want to have less power to weight.
Lugger doesn’t make a more powerful engine that will fit, so in this case, the decision was not really based on brand as much as output requirements. We went with a keel-cooled John Deere 265HP 6068AFM75. This provides 2.65 HP/1000 lbs, which is just about identical to the Nordhavn 55 and 57, although still less than the 50. As an added bonus, the 6068AFM75 is 14% more efficient at rated output, is more efficient across the operating range, and is closer to a continuous duty engine than the Lugger 1066T.2.