The Tektron 35
The cruiser racer that really means it, John Shuttleworth's
flared hull cat points high and reaches fast in surprising comfort.
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
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
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:
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
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
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.
- 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
- 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.