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"A Byte at Tradition"
WoodenBoat Magazine,
December 1987
by Richard Webster
yteTrad2.JPG (30110 bytes)    I was paddling my weathered fiberglass kayak through Seattle's Ballard Locks when I saw a sleek wooden sea kayak with a rising bow and a sexy sheerline. After jockeying my way through a maze of transiently trapped pleasure boats, I nosed up to the graceful craft and met John Lockwood, her soft-spoken designer/builder. He invited me to take her for a paddle, I eagerly agreed, and we switched boats on the shore just outside the locks.
    To me, a kayak's appearance is secondary to how it will perform, especially when my life depends on it. I found that John Lockwood's boat, QUEEN CHARLOTTE, tracked well, turned surprisingly quickly, had reassuringly good secondary stability, and just plain felt great. This was a Greenland style touring kayak worth getting to know.
    Her design? "My computer enabled me to get a very sophisticated, developable shape," Lockwood explained. "I also use my IBM PC to help with the construction; it computed and drew the unsprung shapes of the hull panels."
    When John Lockwood built his first boat in 1971, he was on crutches-and had been ever since 1967, when he broke his hip in a household accident. It was the crutches that indirectly motivated him to build with wood. He had spent the previous summer paddling around the jagged coast of British Columbia's Queen Charlotte Islands in a collapsible soft-skinned kayak. In the evening he would find a campsite and haul the kayak up the beach by hopping forward and lifting, one jump at a time, until he got the boat up beyond the high-tide mark. Because Hecate Strait has an extraordinary 25' tidal range, he often had to hop for more than 100 yards. Determined not to spend another summer protecting the soft underbelly of a folding boat, he decided to build a lightweight wooden sea kayak that he could drag up the beach with towline and shoulder harness.
    Lockwood built his first kayak in the traditional manner-almost. He drew the boat to scale on a drawing board, lofted it full size on the shop floor, and made full sized templates of the sections. Departing from the norm, he then framed only one side of the boat. He cut out half-sections for the 17' kayak, nailed them to a strongback, fitted battens lengthwise at the chine and sheer, and clamped plywood over the full-scale half model. He then marked and cut the plywood sheets, producing unsprung shapes of the panels he needed. Using these as templates, he cut out the other half of the kayak and stitched-and-glued all the panels together. This design/building process took Lockwood nearly five months, working full time.
    Fourteen years and many transitions later, in the spring of 1985, he decided to quit his high-paying city job, redesign his original wooden kayak, and sell it as a kit. He had spent too many years as a computer programmer in Seattle, and it was time to get back to kayaks and work with his hands again-but things had changed. In the decade that had passed since his first boatbuilding effort, he had acquired some incredible new tools and options that were hard to ignore. He decided to purchase the hull-design program AutoYACHT and design the new boat on his personal computer rather than on his drawing board.
    The kayak was derived from native craft illustrated in Adney and Chapelle's Bark Canoes and Skin Boats of North America. But instead of replicating any one Greenland-style boat, Lockwood created his design by copying the basic lines of various kayaks and changing them to make a higher volume boat that could be built from plywood sheets. The most radical change he made was in the depth. Greenland Eskimo boats were used mainly for mammal hunting and had a height to sheer of about 7".  This leaves very little room for your legs and feet, much less for anything else you might want to bring along. Lockwood wanted a high-volume touring kayak that could carry plenty of camping equipment, so he increased that dimension to 9.5".
    On the computer screen, Lockwood entered nine critical measurements from the keel, chine, and sheerlines of his hypothetical boat and observed the resulting hull shape. The interactive program enabled him to graphically manipulate the design; he could change the location of one or more of his nine reference points and see the new configuration. The plan view, profile view, and body plan could be viewed or printed, along with a table of offsets. In 30 minutes Lockwood had the lines and drawings for his new kayak, QUEEN CHARLOTTE.
    The next phase of the design/building process was the determination of the unsprung shapes of the hull panels, the shapes he would need to cut out. Naturally, Lockwood first envisioned the technique he was familiar with. He would have to loft the boat, scrounge up a strongback, build a model (or a half model), and stretch sheets of plywood over that framework. And there was the possibility that the plywood couldn't be bent over the frame-that the boat wasn't developable. If that were the case, he would have to redesign the boat. Although he was no longer impeded by crutches, Lockwood did not relish the exhaustive task before him and sought another solution. He wanted to go from full-scale line drawings to the unsprung shapes of the panels in the easiest way possible.
       Lockwood, who had studied computer science at Harvard, dedicated the next nine months of his life to his project. With the help of Seattle mathematician Frank Pollard and several naval architects, he wrote a plating-development software program called AutoEXPAND. This program, interfaced with Coast Yacht Design's AutoYACHT software, tells you if a hull is developable or not; and it generates the true unsprung shapes of a boat's hull surfaces. If the hull is not developable, the program points out where the problem is so that you can modify the original design as needed.
    At last, Lockwood could get on with his earlier task of determining the unsprung shapes of the panels needed to build QUEEN CHARLOTTE. He no longer needed to clamp plywood sheets over a full-scale frame. He didn't even have to loft the kayak. Nine months earlier he had used his computer to generate the numerical design data that defined the boat. His newly developed program imported this disk-stored data, and Lockwood asked if the surfaces of QUEEN CHARLOTTE were developable. They were. Next, Lockwood had AutoEXPAND do the plate expansions and display both the shapes of the panels as they would appear on the boat, and the unsprung shapes he would need to cut out.
    The first full-sized QUEEN CHARLOTTE came together as if by magic. Lockwood cut his computer-developed panels out of thin plywood (he now uses 4mm Bruynzeel) and laid them out full length on his shop floor. It looked like a jigsaw puzzle with missing pieces. Using butt plates and epoxy, he assembled five full-length strips for his single-chined boat: two side panels, two hull bottom panels, and a deck panel with a pre-cut cockpit opening. He drilled 1/16" holes every 4" along the panels' edges, then sewed the boat together with nylon line and thin metal wire. A single temporary bulkhead was inserted, and the pieces of the puzzle came together perfectly; they were transformed from flat, confusing shapes to a structurally coherent whole that was definitely greater than the sum of it's parts. The 38-lb kayak was completed by gluing the seams together, removing the "threads," and epoxy saturating all the surfaces inside and out. Fiberglass cloth was applied to the hull bottom for abrasion resistance, and the seams were fiberglass taped to strength. As the final step, the designer/builder applied varnish to protect the epoxy from ultraviolet radiation.
    Building that first kayak using only one temporary bulkhead was revealing - the computer's theoretical two-dimensional plating and the real sheets of plywood assumed the same complex multiconic shape, because the bending capacity of the plywood was not exceeded. Actually, there was a slight dissimilarity between the mathematically predicted boat and the end product. The completed boat had a negligibly narrower bow. this could have been avoided by using a series of temporary bulkheads built from computer-generated patterns.
    AutoEXPAND was introduced to the market in 1987 and has been used to develop the surface panels for a wide variety of hard-chined boats, including Lockwood's sea kayaks, steel commercial fishing vessels, and an aluminum Coast guard patrol boat.  It can work on any simple or complex developable hull, regardless of size or building material. The numerical data it creates can generate template drawings or can be fed directly to numerically controlled cutting devices.
    Lockwood's desire to build a kayak evolved into the development of a powerful tool for boat design that reduces construction time and expenses. His advice to baffled boatbuilders: "Get a computer, and join the fun!"
--Richard Webster is an avid sea kayaker and a freelance writer/photographer who lives in Seattle, Washington.

 

 

 

 

 

 

 

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