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The Tektron 35

The cruiser racer that really means it, John Shuttleworth's flared hull cat points high and reaches fast in surprising comfort.

Don Peaslee ©1992

Coming at you, the Tektron 35's hulls are so widely separated that they appear to be only nodding acquaintances. Passing by, this low slung catamaran displays a rising profile that is completely absent of our old visual friend, the sweeping, hard-edged, clearly delineated sheer line. Instead, we see a constantly rounded shape as reminiscient of an aircraft as it is a boat. "That's fine" says Britain's progressive multihull designer John Shuttleworth: "If you're going to maximize the performance of a boat, expect it to look somewhat like an airplane, as they both must slip through the air with a minimum of drag. And build it with absolute dedication to high strength with extremely light weight-also just like an airplane".

This philosophy, and a superior comprehension of the problems inherent in simultaneously driving a sailing vessel through two mediums (water and air), had by the early '80s put Shuttleworth into the forefront of the world's multihull designers. A succession of winning blue water racers had solidified his position as a producer of light, stiff multis (mainly trimarans) that went very fast in difficult waters while proving rugged enough to always stay the course. He also provided the crews of these boats with reasonably manageable, predictable craft that recognized the human factors of fatigue and confidence that were so important to winning the multi-thousand mile, frequently single handed races that were being contested.

A blue water sailor of many years experience, Shuttleworth had often pondered the problem of providing sharp upwind ability in a multihull cruiser while also offering a truly comfortable amount of space to live in. Maintaining good speeds always seemed to require long, thin hulls, with their resulting claustrophobic interiors. He eventually hit upon the idea of designing catamaran hulls with the hull flared a short distance above the waterline, in order to create more living room within the hulls while keeping a fine, easily driven hull shape in the water. His trimaran main hulls already featured this flare, and in 1983 a commission from British yachtsman Bob Sutton for a fast cruising catamaran created the opportunity for his first design of a flared-hull cat. The result was the first Spectrum 42, Timshel, an open bridgedeck (no center cabin) cat with 27' of beam. This successful design led over the next few years to several successors which differed in size and interior details. But all shared the following important characteristics:
  • Modern, light weight, extremely stiff cored construction throughout.
  • Extraordinary attention to reduction of wind resistance.
  • Extremely wide beam to enhance sail carrying ability.
  • Slim, low wetted surface hulls (9:1 fineness or better) flared to a wide hull beam above the waterline to enhance crew accomodation.
  • Elliptical sections forward in each hull which, when to leeward and depressed into the water, cause the bouyancy point to move forward (and, in the weather hull, to move aft somewhat in compensation). This bouyancy shift acts to keep the leeward bow from burying when reaching at high speeds, and also greatly reduces pitching by shifting the water's support of the hull away from its middle and towards its ends.

In addition to the features listed above, let us discuss one other characteristic that Shuttleworth insists his designs possess. "Integrated Structure", his name for a method of laying up composite materials that avoids any obvious "joint" at the hull to beam juncture and other structural meeting points, helps assure that stress points are not created. Stress points occur when a strong area is directly adjacent to a weaker area. The place where they meet is forced to take more than its share of the bending loads, and is prone to early fatigue failure for this reason. The elimination of stress points is particularly critical in the design of a lightweight vessel. Stress point elimination guarantees that loads are evinced as very tiny deflections spread over a very large part of the structure. Their magnitude, even under violent loads, never approaches the elastic limits of the part of the boat being stressed. To avoid stress points, areas of excessive weight and strength are avoided just as much as weakness, as either condition will set the stage for a concentration of stress. Correctly executed, stress reduction design results is a light, stiff structure with its strength well distributed and tailored to its anticipated loads. It will bend, but it will not break. Until the mid-seventies this sophistication of design was available only to the major aerospace firms due to the extremely high cost of stress analysis, which required the use of main frame computers. It then started to "trickle down" to the yacht design field, where Shuttleworth-a graduate engineer-was among the first to reduce the early PC stress analysis and subsequent composite layout programs to practice.

Shuttleworth is adamant about the strength of his vessels. "All of my boats, whether racers or cruisers, are designed to be driven hard offshore, without failure" he said. "I might be persuaded to allow some additional weight in order to use less expensive materials, but I will never allow the strength to be reduced".

The benchmark by which the performance of Shuttleworth's new catamaran designs would be judged was the performance cruising trimaran, which had previously always displayed superior windward performance. By 1986 Shuttleworth was able to announce that his 42' catamaran for Spectrum Yachts was nearly equal in windward ability to a 42' trimaran cruiser-racer, also of his own design-even though the cat had twice the accomodation.

Enter Canadian entepreneur, high-tech executive, boat builder and multihull racer Eugene Tekatch. Founder and owner of Tektron Equipment Corporation, a major supplier of electronic assemblies to North America's automobile and other industries, the level-spoken, otherwise rational Tekatch is completely taken with the racing and building of fast multis. By 1985 he was already a major Shuttleworth design client and in 1988 launched the largest, fastest Shuttleworth cruising cat of the time, the Tektron 50. Tekatch had sailed this boat from Ontario to Bermuda in the summer of '88, and had successfully weathered a near-hurricane by using the T50's moderate wing mast as a storm sail. On his return trip in July the strength of the T50 was inadvertently demonstrated. Reaching at 25 knots, it stuffed and capsized in a freakish current-against-wind sea north of Prince Edward Island in the Gulf of St. Lawrence. Once rescued, and with his injured crewmen being treated, the relatively unfazed Tekatch reluctantly cancelled his entry in the Quebec-St MÅlo Race and took to inspecting his salvaged yacht. Its composite structure had come through nearly unscathed. This demonstrated ruggedness reinforced his confidence in Shuttleworth's design and construction ideas, and was to be emphasized in the Tektron 35, a craft then on the drawing board that was scheduled to be the Tektron Marine Division's production entry in the high performance cruiser-racer market.

The new T35's forebear was a craft that had been christened with one of the most splendid, evocative names ever applied to a catamaran. "Two Hoots" is an open bridge deck, 35' Shuttleworth flared hull racer/cruiser that was built in 1987 by Scotsman Curly Mills of County Fife, who soon established the new yacht's reputation with a victory in the 1989 running of the Scottish Islands Peaks Race. Reviewing the boat's track record and the space available within its commodious hulls, Tekatch found an attractive platform from which to develop the T35. He envisioned the new boat as a combination of performance and accomodation that would have no direct competition within the marketplace.

But the idea of a new Two Hoots-based Shuttleworth cat had occurred not only to Tekatch. Fascinated by Two Hoots, Marblehead yachtsman Ted Grossbart had already been in communication with Mills concerning his boat, and was shortly to discuss a modified successor with John Shuttleworth at the Newport Multihull Symposium in June of 1988. Tekatch was waiting in the wings for someone to show interest in the new design, Shuttleworth introduced them, and Grossbart's position as Tektron's kickoff buyer for the T35 was committed that fall.

Tekatch's customer for T35 #1 was a member of the new wave of multihull enthusiasts. Dr. Ted Grossbart is a Marblehead psychologist and prior owner of a succession of one-hullers, culminating in a C&C 40 that he skippered in 1981 to the Azores, where he became one of the exclusive few to painstakingly, proudly paint his boat's name on the famous sea wall at Horta. Athletic, analytical, hands on and very self contained, Grossbart started his multi career in the mid '80s by rebuilding a Vince Bartalone designed 28' Warrior catamaran. The Warrior provided great experience and lots of fun, but proved an increasingly tight fit for his growing family. To determine the Warrior's successor, Ted embarked on a two-year study of catamaran designs so thorough that he ended up in Australia at one point. But his quest ended with a vessel inspired by the efforts of a Scotsman, designed by a South African now resident in England, and built a day's drive away, just over the border near Hamilton, Ontario.

The triumvirate of Shuttleworth, Tekatch, and Grossbart-abetted by the practical advice of Curly Mills, Two Hoots' owner-proceeded to the task of distilling a host of possible ideas into the specification that would describe the first T35. The lanky Grossbart pushed for and got a substantial increase in headroom; the North Americanization of Curly Mills' Scottish speedster had started. During previous cruises on the Spectrum 42 Miranda Shuttleworth had impressed upon husband John the desirability of relocating the dining area. The dining table and seats, located in the middle of the starboard hull, created too great an impediment to movement forward to the galley, head, and forward double berth. The final answer was to move the dining table of the T35 to the aft end of the hull, abaft the companionway from the cockpit. This made the galley longer and freed up movement all around. But good leg room within the dinette required more beam, so the flare of the hulls was increased-resulting in over 6' of beam at eye level, and an even larger port aft double berth than had existed in Two Hoots. In the end the T35 had grown noticeably in volume, but not particularly in weight. It was now even easier to live in, albeit at a small increase in projected and surface area from that of Two Hoots. But unlike Two Hoots, the T35's deck edges are rounded to reduce resistance, and Shuttleworth feels that there has been no net increase in upwind drag from that of the T35's Scottish predecessor.

The size and shape of the boat above the waterline are very important. Shuttleworth's aircraft analogy to boats is not just limited to construction. He emphasizes that a vessel's windward ability will be limited by its lift over drag (L/D)- both of the immersed hulls and of the vessel above the waterline, which is subject to the very substantial effects of wind resistance. The T35's rounded hull decks were not just to enhance torsional rigidity (which they do); they also were designed to minimize drag. Nor is the absence of the popular bridgedeck saloon uncalculated; Shuttleworth contends that the projected area it would add upwind would cost as much as 3 degrees of pointing on each tack. Our mind's eye may always picture a multi screaming along on a reach, but the T35's most difficult jousts are likely to be hard on the wind, against sharp sailing trimarans and serious keel sloops. The reduction of drag is critical here. In addition to keeping drag low, great attention is paid to the all-important windward factor of maintaining a tight, straight forestay. Carbon fiber braces the mainbeam against the enormous download of the rotating carbon mast. Running backstays can be set up to augment the already substantial forestay tension imparted by the cap shrouds. Carbon fiber distributed through the integrated structure fights the loads that bend hulls and beams to create forestay sag, particularly in a seaway. "Right", you say- "but let's get back to wind resistance. Aren't those wide, comfortable hulls going to create a lot of wind drag going to weather ?" "No", says Shuttleworth, and here's the rather surprising answer why: A fat-hulled cat and a skinny-hulled cat of the same height and beam present the same projected area when viewed from ahead at a 30 degree angle-which is as close as you will ever sail to the wind (see sketch). Isn't this having your cake (performance) and eating it, too (room below)? It would appear that way; projected area is fundamental to drag, all other things being equal. Whether all things are equal isn't known, as the difference in the drag of the complex, confused airflow around fat versus skinny hulled cats hard on the wind is a bear to measure and even harder to arithmetically model. Powering dead upwind will of course be more wind resistant for the fat versus skinny cat; there is then definitely more projected area opposing the wind than if the hulls were thin. Meanwhile, Shuttleworth's position is that roomy accomodations and close-winded sailing performance can be provided in the same yacht, and the demonstrated windward abilities of his flared hull cats appear to bear him out.

Rosebud, Tektron 35 #1, now rides at its mooring before Ted and Rose Grossbarts' Marblehead shoreside home. The boat's dominant color is red, a red sled-just like the sled in Citzen Kane. And if watching the Tektron 35 go by for the first time is a memorable experience, so is one's first trip aboard. After climbing the stern stairs over the aft crossbeam, the enormity of the cockpit-over 10' wide by 14' long, measured to the seat backs-makes Grossbart's story of a 30 people for cocktails at Edgartown easy to believe. Out front, the two distant, widespread bows are spanned by an arched carbon fiber beam instead of the aluminum tube originally specified, a testament to Tekatch's respect for the strength of integrated composite structures after the metal failures he experienced in his capsize. Descend the three stairs into either hull; the interior beam of over 6' provides generous shoulder room and makes moving past others easy, despite the cabin sole's somewhat narrow width (it's in the thin part of the hull, below the flare). The feeling of interior space is emphasized forward of the port companionway , where the room extends nearly another 4' towards the boat's center, abaft of the main crossbeam.Starboard is the social hull, with its 8-person dinette, large galley with a propane fridge, and wall oven with broiler. There are big sinks and all sorts of counter space and stowage, and a double berth forward. The port hull provides quiet and privacy, with doubles fore and aft and a pullout double over the chart table. Both hulls have heads, just abaft the forward berths; the port side also has a shower. And those berths. The forward doubles are 64" at the shoulders, a figure seldom measured in any multihull. But an astounding 70" is the size of the port after, a figure unmatched by any of the cats at the Newport Show, including the big French ones. My wife and I shared it for one memorable night. Bliss! One can roll over, instead of "twisting in place!".

But enough of these domestic enticements; people buy boats like these to sail them. Rosebud's high-tech hulls are generally very rounded in order to present the lowest wetted surface for the load carried. The static waterline is long and quickly stretches nearly to hull length once the boat has a few knots on. Her weatherliness is abetted by the use of one large daggerboard located in the port hull, first successfully tried by Curly Mills on Two Hoots. Analyzing and refining the idea, Shuttleworth found that two boards were efficient only if one is willing to "switch" after each tack-leeward board down, windward board up. But most cruisers aren't willing to do this, and leaving both boards down creates too much drag. So he uses one, giving up a very small loss in performance when the board is to windward, but gaining a great deal in weight and cost reduction along with more room within the starboard hull. (Note: One does NOT fly hulls on cruising cats). Rosebud points high; we have seen 85 degrees between tacks, full and by, using the full main and her tall, self tending blade jib. For light air she also carries a large roller furling genoa to bolster the sail area numbers. Raked quite noticeably, the rotating 50' carbon fiber mast carries a full battened, highly roached 457 square foot mainsail. Rosebud has cut the waves at just over 20 knots, so far, under working sail. For light air reaching the spinnaker is bent to the bows without using a pole, but a bowsprit is now being planned that will be used both for the chute and the genoa.

The visual sensation of driving the boat is closer to that of a beach cat than a bridgedeck saloon boat. There is no high cabin roof to constantly peer over, and one stands or sits in the cockpit, not on an elevated steering seat. Visibility is superb and right in front: bows, trampoline, lobster trap buoys, splashing waves, separated from the cockpit only by the streamlined, sloping main crossbeam. Rosebud sports a tiller on each side of the cockpit; use whichever you desire. Subsequent boats have dual hydraulic steering wheels, as Rosebud can test your arm after a while-not because of weather helm, but because of the friction associated with two kick-up rudders, two tillers, several sheaves, and their cables. Shuttleworth's bouyancy center strategems to keep pitching under control appear to work quite well. The boat also tacks with good confidence, particularly in view of its enormous beam of over 24'. Just make sure that the jib is up; this is not a mainsail only boat in normal air conditions, although triple reefed main alone is felt to be her last storm rig. Actually, Rosebud's ultimate storm sail is her mast, and Shuttleworth believes it will be very effective and controllable in the role. Rosebud mocked all our efforts one day to get her out of irons (or even complete a tack) on main alone in very light air. But run her the way she requires ( a condition of success with most multis) and the excitement and performance is there to be had. Lots of multis will frequently log knots in the high single digits, with a shot at 10 once in a while. But this lightweight (6000 lbs) T35 frequently runs in the low doubles, with a shot at-18? 20, maybe? To our great satisfaction, Rosebud this past fall slowly ground down a well-sailed, Kevlar-equipped 42' IOR sloop of some distinction on a course just slightly cracked off from close hauled. This was the element of the performance profile Shuttleworth insists is so important. It's fun to reach, but a high performance boat must point, if it is to finally win the day.

Tektron, meanwhile, has completed and launched T35 #2, destined for Katamaran Konstruktions GMBH, its dealer in Europe. Number 3 will be delivered to its midwestern owners in late summer to start a long-planned ocean sabbatical. The expected detail changes resulting from Grossbart's experiences with Rosebud have been incorporated as possible within the build cycle of each of these boats, along with wheel steering and some other modifications suggested by Dr. Martin Mai, director of Katamaran Konstrktions. T35's 1 through 3 were all built using the male mold method of construction, which is cost efficient for very small quantities but is very labor intensive and slow. Taking a deep breath, Eugene Tekatch has now made the very expensive commitment to production molds for the T35; they should be approaching completion as this is being printed. The molds will make possible the production of boats as good or better than the first three in a fraction of the previous build time, and will make Tektron the first volume builder in the world of a Shuttleworth design. And whatever became of Gene Tekatch's big T50 and his plans for blue water racing? Well, the open bridgedeck T50 #1 was refurbished and is now a deluxe dive boat in the Pacific. But T50 #2 , a magnificent looking bridgedeck cabin version, was launched in the spring and is now sailing the East Coast. Owner-skipper Rick Starr has extensive cruising plans and will probably also enter his big cat in some of the major oceanic races. Tektron, meanwhile, will focus its attentions on producing T35's for what Tekatch hopes will be a sizeable and enthusiastic market.