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The Nordhavn 56 Motor/Sailing Performance
March 16, 2009
By Don Kohlmann
Ed. note: Don Kohlmann is the sales manager of our Nordhavn Yachts Northwest sales office. He has had an extensive sailing career that has rendered him a bit of an “expert” in the area and we are pleased to present his take on the capabilities of the brand new Nordhavn 56 Motorsailer. Don’s been sailing boats nearly his entire life and for well over the past 30 years has made sailing his profession. Early on in his career, Don worked as a rigger and project manager of race boats, followed up by positions at Ericson Yachts and later Pacific Seacraft where he was promoted to General Manager of the company. He has spent countless hours racing, practicing and testing a myriad of hulls. And along the way, he has sailed with some of the best names in the industry including Lowell North, Dennis Connor, Tom Blackaller and Paul Cayard, participating in projects such as the America’s Cup programs, various IOR campaigns and several 6-meter campaigns, one-design programs and the Santa Cruz series of “sleds”.
Although the motorsailer concept is not new, it now has more versatility and value than ever. The apportioning of a motorsailer’s sail-to-power, or power-to-sail, bias has always been a trade-off, but the advances in machinery, deck hardware, and sail technology have made it more attractive and enhanced the all-around performance by making sail handling easier, and sail and engine power more effective and easier to integrate. To be successful requires a great design. The Nordhavn 56 is the product of a designer, Jeff Leishman, and a company, Pacific Asian Enterprises/Nordhavn, with critical experience designing and building both cruising powerboats and cruising sailboats.
There are many reasons to be attracted to a motorsailer that could perhaps be summarized by a combination of the following points:
For folks who don’t feel comfortable going offshore without a sail
For fuel conservation – extending the cruising range, even in light air, with sailplan flexibility to create supplemental power and substitute power
For stability and roll resistance
For water collection – the mainsail can be a very effective watershed
For aesthetics – quiet propulsion when conditions permit
For the interior volume afforded a boat that is not biased primarily toward sailing
For a view underway whether from the pilothouse, or from the forward steering cockpit
Nothing gives a vessel windward and all-around ability like an engine and propeller. Early tests under power have had the N56 easily achieving speeds of 10 knots. The combination of a well balanced hull and sailplan, plus the 165hp Lugger diesel engine driving a Hundested variable pitch/feathering propeller – as significant as its cost is − provides the optimum interface between sail propulsion and power propulsion through a very broad range of conditions, and ties together every point referred to above. The N56 drive train completes the motorsailer concept by providing the ability to adjust the power output, and attendant fuel consumption, to complement the power developed in the sailplan.
Performance Under Sail
Ever since the inception of the Nordhavn 56 Motorsailer, the question of performance under sail has been the most pivotal. Now we can say unequivocally, that the boat fulfills its purpose extraordinarily well – the interior living and operating areas are spacious and comfortable, and the performance under power and under sail is superb. The results of our early light/moderate air sailing trials prove that the sail plan, in addition to being a supplemental source of propulsion, is also a substitute source as well. In fact, the results are as impressive for the 56’s windward ability as they are for its speed through the water.
Our early trials with working sails – full mainsail and 100% high-clewed headsail - were conducted first in light-to-moderate conditions of 8 to 13 knots true wind speed (TWS), averaging 12-13 apparent wind speed (AWS), and then, on a subsequent day, with an asymmetrical 1.5oz. all-purpose cruising spinnaker in true wind speeds averaging 11 knots. The water conditions were light Pacific swell and light chop as the accompanying photos will show. The 100% headsail is built of suitable cloth weight for widely ranging conditions, and by its clew height is intended to produce minimal sensitivity to lead position, better visibility under the foot of the sail, easier and more even furling or roller reefing, and to allow more room on the headsail lead track for furled lead positions. The fact is, that it was under its wind range, and actually limited the boat’s performance in our test conditions. The tank conditions were full fuel and full water. The boat is in live-aboard condition with respect to stores and personal gear.
These conditions and the sail combination are one of the truest tests of basic performance under sail for any boat. Going upwind at apparent wind angles of 50 degrees produced apparent wind speeds of up to 15 knots and boat speed through the water of 5.6 knots, with no indication of excessive leeway. Tacking angles were a very respectable 130 degrees on the compass - especially given the boat’s relative shoal draft of 6 feet - and would clearly be closer in the wind range of the headsail, or with a larger headsail.
As we sailed wider apparent wind angles (AWA), 70 degrees yielded a speed of 6 knots, and in these conditions, further off the wind to 120 degrees resulted in reduced boat speed of 4.25 knots as expected.
The next day’s results with the cruising spinnaker in conditions that averaged about 9 knots true wind speed, produced speeds of a solid 6 knots at an apparent wind angle of 75 degrees and 11 knots of apparent wind. The results are shown in the table below.
Tacking Angle on Compass
1.5oz. Cruising Spinnaker
Tacking Angle on Compass
Aside from straight line speed through the water, the 56 responded very nicely to the helm when manually steered and was very easy on the autopilot when engaged. The helm felt quite neutral, and most pleasing of all, it showed no tendency toward lee helm which saps the windward ability of many cruising sailboats, especially those in the heavier displacement-to-length and sail area-to-displacement ratio categories.
There are often conditions in the ocean when the wind velocity would provide sufficient propulsion, but the wave conditions will not allow the boat to accelerate sufficiently to build apparent wind. The result is that the boat will tend to slat in away that will prevent the sailplan from being effective at propelling the boat and also prevent it from producing an effective component of stability. The addition of engine power creates forward motion, which, at the right apparent wind angle, will create enough apparent wind to render the sailplan effective at supplementing the engine power and at providing roll resistance. As it does, the boat will settle down, the flow around the sails will remain attached, sail shape is maintained, and the engine power can be reduced to the threshold necessary to keep the process going. Under some conditions, this apparent wind feedback benefit could occur with very light true wind, but very flat sea conditions.
Sail setting and sail trimming were quite easy with the Lewmar self-tailing hydraulic winch package. With the push of a button for the main halyard winch, hoisting the mainsail is quick and smooth. The same hydraulic winch can be used with the Leisure Furl boom furling line that rolls the mainsail in and eases it out. The mainsail luff tape feeds smoothly into the luff groove with negligible drag. The beauty of the boom furling system is that the mainsail remains fully battened and retains plenty of draft to give it the kind of power required to achieve the lighter air performance that we experienced. In addition, all of the mechanical components of the furling system are near deck level for easy inspection and maintenance.
With the hydraulic furling system for the headsail, setting it is even easier. As with the mainsail, the sail rolls in and out very smoothly, and is trimmed using the hydraulic sheet winches mounted at arm’s length just outside the port and starboard pilothouse doors.
The hydraulic spinnaker sheet/secondary headsail winches are located in the aft cockpit just outside the aft pilothouse door and provide the same ease of trim as the headsail winches.
It doesn’t take long to adjust to monitoring sail trim from the pilothouse. It’s a comfortably advantageous vantage point.
Please note that hulls #1 and #2 are currently at our Dana Point location, and #1 will run north to arrive here in Seattle, by the end of April, in time to go on display at the Anacortes Trawler Fest, May 7-9, 2009.
Don Kohlmann is the sales manager of our Nordhavn Yachts Northwest sales office. He can be reached at email@example.com.