What to expect from a wooden sea kayak clad in epoxy and fiberglass? This page may help to answer most of your 'Frequently Asked Questions' about wooden kayak construction.
Mechanical principles of Composite Sandwich Cores. This page casts some light on the nitty-gritty technical stuff.
You may wonder, can
I even build a kayak like this? If you like a little challenge, you
certainly can! There are thousands of wood strip kayaks around the
world, many made by people for whom this was their first building project
of any kind. The vast majority of builders are the 'weekend warrior' types
who relax by this artistic endeavor.
Monocoque shells are structures where the walls support themselves including all other loads and stresses. They don't need any internal reinforcement such as ribs, stiffeners etc. This eliminates a lot of superfluous weight. Even smaller craft such as single skin fiberglass kayaks are monocoque but as their size increases such as in expedition or double kayaks, the skin needs to be built thicker to maintain sufficient stiffness. The price of that is exponentially increasing weight.
This is where wood strip sea kayaks really shine! The composite core has sufficient reserve stiffness and strength that even much longer and larger Expedition kayaks can stay light.
All this means is that everything you do with the kayak is simplified.
Loading and unloading kayaks, for example, can be quite a chore but my even my wife can put a strip kayak on a car roof with ease. Low weight also means easier paddling, maneuvering and covering larger distance with less effort.
Take an 18ft single skin fiberglass kayak (heavyweight), for example. It will weigh about 60 to 64lb and its kevlar counterpart can shave this by about 6lb. Compare this to a solid red cedar kayak of the same size. Its weight will span from 39 to 50lb max. depending mostly on the fiberglass lay-up.
It gets better still; A 21ft fiberglass double will be around 85 to 95lb but the same double "stripper" such as the Cape Ann II will be no more than 75lb! This includes hardware, rudder and everything else attached. So, while the commercial builders struggle to shave 2-3lb with the latest vacuum bagging techniques, with a 'stripper', you get an immediate 10-15lb weight saving bonus!
Let me say a word of caution about exotic wood. If you want the lightest possible kayak, limit your inlays and decorations to Cedar and low density wood. Careful use of hardwood is fine but don't be surprised that one 18ft strip of beautiful Bubinga may weigh as much as 1lb (ugh!).
The most suitable wood in terms of weight and workability:
Strength & StiffnessThe mechanical properties of the sandwich core are the main source of strength but there is an additional bonus that comes with wood strip kayaks.
The cedar strips forming the kayak are inherently stiff and strong themselves, making the shell far stronger than if it was built using a different core. Of course, all other variables remaining the same (thickness, lay-up etc.). No other lightweight core material I know of (besides plywood) has the same self supporting qualities. You will notice this unmistakably, as soon as the kayak mold is completely stripped. The 1/4" shell stays rigid even in the spans between the stations of the form. There is no flex when you sand or plane.
One enormous advantage of a rounded wood strip kayak is its 'compound' shape. Ever tried to 'flex' an egg shell of an unbroken egg? It is enormously stiff because of its compound shape, not the thickness of the shell. Once you break the egg, the shell is as fragile as glass. This lesson of natural design was quickly learned by medieval architects who realized that the only way to build large cathedrals was with 'compound' domes not flat roofs. The examples of this principle are everywhere around us and the same applies exactly to the smooth round surfaces of wood strip kayaks.
A flat plate such as a plywood panel will always be less stiff than a compound shell made of the SAME material and thickness.
Because of this structural advantage, you will be very surprised how solid the whole kayak feels when it plunges into deep wave troughs - a massive slam without a shudder in the hull. When you are out there, far away from the shore and you get in a really 'hot water' you will thank yourself that you are riding a solid wood core kayak.
InexpensiveOne nice thing about wood strip construction is that the entire sea kayak can be built inexpensively with a few specific but basic tools.
If you have a table saw and a router, making your own strips will make the project cheaper yet. You can rent these tools but if you don't want to go to this length, you can order quality wood strips commercially.
So that is it. As far as boatbuilding is concerned this is as minimalist as one can be.
If you would like to see all the tools I use, visit the Kayak Shop.
The actual cost of wood for an 18ft kayak such as the Cape Ann is $144 and it assumes you make your own strips from planks ($3 / ft^2). About 3 planks (3/4"x10"x16') are needed altogether. The rest of the materials, mainly fiberglass and epoxy adds another $400 to $600. Altogether, a top notch wood strip kayak comes to about the same price as a low-end polyethylene kayak.
For a more detailed account, see the Cost Estimate page for the Cape Ann Double. The Kayak Building Manual also gives a detailed account of materials and generally strives for the most cost effective ways of building.
Another way to look at this is that wood strips make for the cheapest core material bar none! You would be hard pressed to build a solid core kayak from a different material for less than 4 to 6 times the cost of cedar core.
And of course, a labor of love is FREE!
Beauty of Wood
The character of wood
grain and inlay under gleaming coats of varnish is hard to deny. I am
not alone in believing that wood strip sea kayaks are the most beautiful
craft of its kind.
Fast Building Time
Strip building is not
the quickest way to build a kayak. The reason I say it is fast, because
IT IS the fastest method in its category - that of potentially efficient
hulls such as female molded shells or otherwise material unrestricted
hullforms. If you require a faster building time, check out the stitch
& glue Cirrus or the Cirrus
Uncompromised Hull Form
I mean it when I say
that this factor alone convinced me to go the "strip built"
route. I have yet to stumble over an obstacle that prevents me from developing
the kayak hullform exactly as I want!
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No matter what kayak
type you have, there is always some compromise to deal with. Plastic kayaks
weigh a ton and are slow, composite kayaks are expensive and are heavier
than 'strippers', fabric kayaks rip and need very high maintenance, plywood
kayaks do not have the aesthetics of strip kayaks and most do not have
the optimal hull forms at that. Wood strip kayaks do have a weakness and
that is that they are sensitive to impact.
If the maintenance work
is a con, the results are a definite pro. If you use your kayak a lot,
it is a good idea to wet sand the dulled varnish every three years or
so and put on a new coat. Two afternoons is not such a terrible price
to pay to give your kayak a "brand new" look.
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Stoneham, MA. 02180
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Last page update: 29 October 2013