Sparkman & Stephens Dark Harbor 20 - A Real Knockout Knockabout

So this is just about my ideal version of a knockabout sloop with only one exception, its age. I am looking for a modern Knockabout Sloop so I can maintain a fiberglass and aluminum boat rather that a wood one. But she sure is tempting and beautiful. Here is what her designer Olin Stephens had to say about the Dark Harbor 20 in his book "Lines: A Half-Century of Yacht Designs by Sparkman & Stephens, 1930-1980"

Dark Harbor 20
Design No. 68, 1934
Lenght Overall: 30' 2"
Datum Waterline: 20' 0"
Beam: 6' 6"
Draft: 4' 2"
Displacement: 4,800 lbs
Sail Area: 380 sq ft

The Dark Harbor 20s were new in 1934 and they are still sailing actively. I have always been sure that Clinton Crane, the distinguished Glasgow-trained navel architect whose designs included the J-boat WEETAMOE and the twelve meter GLEAM, was responsible for putting the design in our hands, and have been gratified that the

class met the needs of the Dark Harbor summer community on Isleboro. My recollection is that sixteen boats were originally built by Lawley in Neponset, Massachusetts, and all are still sailing with the help of some replacements parts and good upkeep. Five locally-built boats were added to the fleet just after the war with no difference in performance. The one-design character of the class has bee well maintained

I think longevity of the class is due to the fact that the boats are simple, relatively easy to build and maintain, and well-balanced in their ability to meet the varying weather conditions, averaging moderate to strong south westerlies. They are nimble, exciting to race, and typically carry a crew of three in addition to the skipper. Displacement is light and beam is moderated toward narrow; the hull easily driven. Draft of the fin keel is al

so moderate. The fractional sloop rig seems suitably proportioned. The boats are also attractive in appearance, as would be expected of a class sailed in this stylish and long-established enclave.

Drake Sparkman, my partner, and I worked with Henry Nevins, who was then considered the best wooden boat builder, on a boat called GIMCRACK that ended up being the prototype for the Dark Harbor 20. We built GIMCRACK in 1932 hoping to get the commission to design the new International One-Design class for Long Island Sound. We missed out on that one, but we had this boat when Clinton Crane asked us to design the Dark Harbor class.

The historical significance of GIMCRACK lies also in that she was one of our first designs used to establish the validity of tank test data. We took her out and carefully measured the speed of the boat in two or three different ways. We did the same for the wind velocity and heel angle, the pointing angle, and as much of that kind of data as we could accumulate. We worked out the sail forces we had to achieve to drive the boat, and, having tested the model of it, actually towed the boat itself to confirm the model test.

Having the ability to test a model in a tank at relatively low cost made it possible to check a lot of new ideas and to make some real progress. Thus, the design for GIMCRACK and the Dark Harbor 20 was really kind of a pioneering job, the first experiment in a long series that provided reliable answers in knots as to how fast a boat would go.