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With the development of the 62, P.A.E. began extensive tank testing of new models in order to verify hydrodynamic characteristics of hulls, with emphasis placed on resistance and “seakeeping” qualities. Most Nordhavn displacement hull forms are tested with both conventional as well as bulbous bows. The bulbous bows have been used for years on most tankers, freighters and large fishing vessels because the bulb reduces hydrodynamic drag at the speeds ships travel resulting in a considerable fuel savings. P.A.E.’s interest in the bulbous bow was originally focused on reducing resistance, improving efficiency and thereby increasing range. By affecting the bow wave, tank testing has shown that a bulbous bow reduces resistance in the range of 3 to 15 percent depending on the model and speed. This reduction in wave making resistance allows less horsepower to be used for a given speed, thereby increasing range, reducing engine rpm with a corresponding decrease in noise. While the primary benefit of bulbous bows was to increase efficiency, it was noted that that they also contributed to decreases in pitch motion on some models. Pitch amplitude on the Nordhavn 62 was reduced by 20% and pitch acceleration was reduced by l8%, contributing to the “seakindliness” of the boat in most sea conditions. The success of the 62 has lead to similar bow designs on the 57 and 50.
Extensive tank testing has determined that the benefits of a bulbous bow are most noticeable on boats 50 feet and longer. Because there is a relationship between the ideal diameter of the bulb and the existing area of the mid-ship section, a number of issues become inherently impractical with smaller boats. Tank testing during the Nordhavn 40's development did not show an appreciable reduction in resistance or pitch.
Extensive tank testing of the Nordhavn 62 revealed added benefits to the bulbous bow design including a noticeable reduction in pitch motion
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