The key to a successful hull design is efficiency, as it is vital that the boat move through the water with the least amount of effort in all conditions. As detailed in the P.A.E. company brochure, the displacement hull is designed to run most efficiently in the speed/length ratio range of between l.l and l.2. The boat's ideal ocean crossing speed is therefore computed by multiplying the square root of the waterline length by l.l or l.2. In the case of the Nordhavn 57, this ideal speed is between 8 and 9 knots, and at this speed it has a range in excess of 2,600 nautical miles. At the more customary cruising speed of l.34 S/L, the 57 will achieve a very comfortable, efficient 9 to l0 knots. Here, the 57's speed is optimum for most long distance voyages. She's running quietly and smoothly, and she's moving along at a speed that covers 240 nautical miles every 24 hours.

Appreciating the needs of today's time conscious owner, P.A.E. worked even further on improving the upper speed range of the 57. With the help of extensive tank testing, the hull design was refined to include the utilization of a parabolic shaped bulbous bow, full sections aft, and a stern which minimizes drag-inducing suction at higher speeds. The results were significant gains in efficiency, allowing the boat to run easily at the S/L of l.5, or approximately 11.5 knots. At this speed, the Nordhavn 57 has a range of l,400 nautical miles, making it ideal for coastal cruising or wherever a medium cruising range is called for. If an owner wishes even higher speeds, the 57 can be ordered with twin engines. This arrangement will provide cruising speeds of ll to l3 knots.

Because the efficient speed range of the Nordhavn 57 has been extended to 11.5 knots, the vessel appeals to those who have been considering planing speed motor yachts or semi-displacement "fast trawlers." It offers reasonable speed without all of the costs associated with attaining higher speeds. For large vessels to achieve planing speeds, enormous amounts of horsepower are required, and sometimes drastic weight-saving construction techniques must be followed. Add the effects of light displacement-to-length ratios, small rudders and shallow keels, and the results are often noisy, fuel-guzzling boats that behave best when at the marina. Some popular semi-displacement hulls are being fitted with oversized engines in an attempt to satisfy the latest marketing demands of going fast, but these hulls are often being pushed beyond their limit. The resulting ride is wet, rough and noisy, as they are being asked to do what they were not designed to do. Alternatively, the overall operation costs of a modified full displacement hull are often a fraction of what planing or semi-displacement boats run. With a single, moderate sized diesel engine doing the job, fuel and maintenance costs are far less than with two high horsepower engines, noisily pushing a boat beyond its comfort level.

The question must be asked, "How fast is fast enough?" Owners who have had faster boats have found the overall performance of a full displacement hull to be far superior to their previous planing hulls. One new Nordhavn owner said, "This was the fastest voyage I ever made in the slowest boat I've ever owned." Indeed, running in the range of l0 knots is often sited as the most ideal speed to enjoy the experience of being on the water while at the same time having a sense of getting somewhere in a reasonable amount of time.