Building One-Off

December 05-January 2006

This is an article from WaveLength Magazine, available in print in North America and globally on the web.
To download a pdf copy of the magazine click here: > DOWNLOAD

by Doug Alderson

A ‘station’ showing stringer locations.

The kayak is the most personal of boats, and there is particular pleasure and satisfaction in designing a kayak for yourself, for your body, and for your particular purpose. If you are to design your own kayak, a few design parameters must be established at the beginning. A kayak for long-distance touring will be larger and heavier than one designed primarily for car-topping and afternoon excursions. You can get a good start by taking critical measurements of kayaks that you already prefer, then make modest design adjustments to fit your personal girth, height and weight.

With the length, width and general shape of the design decided, the process of lofting the lines begins. Lofting is a methodical drawing technique and the most technical part of the design and building process. I will leave this for other authors to describe as there are innumerable books on the processes. The result of lofting the lines is a table of offsets that numerically define the shape of the hull. This is a standard process used in the early design stages of most boat building. If you get this far you will be compelled to see your dream come to life.

Stringers in place on the stations. Clamping hull sections in place.

From the table of offsets, a set of ‘stations’ can be drawn fullsize on paper and then sawn out of plywood. The finished sections are erected on vertical supports attached to a long, stiff beam known as a ‘strongback’. Great care is taken to align and secure the frames in the correct position to form a skeleton. The kayak will be built onto this skeleton and the skeleton will be removed afterwards. Small peep-holes can be drilled along the centre line of each section to help line up all of the sections visually.

Planing the bevel.

Stringers of clear grained Douglas Fir are firmly but temporarily fastened to the frames and will form the keel, chines and deck seam. Browsing the local lumber suppliers I can always find one long piece of two by four (or larger) with enough clear grain to do the job.

Draw a centerline down the length of each stringer and then, laying a plane across two stringers, plane off the excess wood from each stringer to form the bevel angle necessary to begin planking the hull. Where the length of plywood is insufficient to extend the full length of the hull, the plywood can be ‘scarfed’ or butt-jointed. Rough-trimmed pieces of plywood can be glued, stapled and clamped onto the now beveled stringers. Once the glue is dry, the staples can be removed and the excess plywood can be planed back to the centerline of the stringers.

Scarf joinery.

The scarf can be formed by simply planing the scarf with a hand plane. Throughout construction, all gluing is done with marine epoxy, thickened with micro-fibers. These very short fibers add considerable thickening, gap filling, and strength to the glue joints. Surfaces to be glued need to make good contact but a precision fit is not necessary.

The quality of the plywood used is a personal choice. I have successfully used everything from very cheap door-skin to moderately expensive marine grade plywood. I do not use the heaviest of resin saturated marine grade plywood which is in common use by yacht builders because this plywood is more expensive and so stiff that it is not as easy to work with.

I design the deck a piece at a time as I build. I sit in the open hull and arrange the height and curve of the deck to suit my own body and my personal sense of what is right and looks good. The deck is formed over six or eight, 4 cm wide battens that are strategically arched across the hull. Plywood can be gently bent over and glued to these battens.

Battens and bulkhead placement.

Cunning assembly of as many as 20 small pieces is needed to form the curvatious shape of the deck. Filling and fairing with epoxy resin and micro-spheres smoothes the many joints. Recessed hatch openings and cockpit coaming pieces are constructed and fastened into the deck with epoxy and fiberglass cloth. After a section of the deck is roughly constructed, it is removed from the hull and the underside is fiberglassed and then reattached and glued onto the hull.

When hull and deck are assembled, the exterior of the hull is covered with 6 oz fiberglass cloth and bonded with epoxy resin. The deck can have a lighter 4 oz cloth covering. The edges of each application of fiberglass cloth are overlapped by at least 5 cm. Seams are sanded to a feather edge to appear smooth and seamless. The entire kayak is lightly coated with a thin, easy to sand layer of epoxy mixed with micro-spheres. Additional layers of epoxy and microspheres are applied until a smooth and fair surface is obtained.

Building the hatch coaming.

Deck and hatch fittings can be purchased or custom built. I have also built dagger boards and skeg boxes into some kayaks. Seats and rudders are a couple of more features to acquire or build yourself. A recessed area for a deck compass and plumbing for a foot operated bilge pump adds to the many design considerations. I finish with marine enamel paint applied with a roller and tipped with a sponge brush to leave a smooth surface.

After it is all done, the finished weight is about 25 kg, comparable to a standard fiberglass construction.

Deciding to travel by sea kayak is an expression of the desire to do more with less, to simplify an otherwise harried existence, and to get closer to nature at least for awhile. The sea kayak is a marvelously seaworthy craft in the hands of a skillful and prudent paddler, capable of navigating conditions in which any other handpowered craft would founder.

“In the past, the kayak was a tool for subsistence hunting and, as an integral part of a struggle to survive, also held spiritual value. Beyond the utilitarian uses of the hunter-gatherer, independent travel by kayak has long been a metaphor for life and spirit. The simple practice of pulling the boat forward, one paddle stroke at a time, with uncomplicated human effort, has not changed; all paddlers share in this experience. While today the primary purpose of kayaking has changed from subsistence to recreation, paddling as a means for spiritual transportation remains relevant.” From Sea Kayak Around Vancouver Island by Doug Alderson.

Doug in his workshop.

© Doug Alderson works with Sea Kayak Instruction and Leadership Systems(SKILS) www.skils.ca in Victoria and can often be found in the vicinity of the Victoria Canoe and Kayak Club. www.vckc.ca. He has written three books on sea kayaking: Savvy Paddler, Handbook of Safety & Rescue, and a guidebook for Sea Kayaking Around Vancouver Island.