Strip-built, or "strip-plank
Epoxy is the family of basic components or cured end products of epoxy resins. Epoxy resins, also known as polyepoxides, are a class of reactive prepolymers and polymers which contain epoxide groups. The epoxide functional group is also col ...
", is a method of boat building
. Also known as cold molding
, the strip-built method is commonly used for
A canoe is a lightweight narrow water vessel, typically pointed at both ends and open on top, propelled by one or more seated or kneeling paddlers facing the direction of travel and using a single-bladed paddle.
In British English, the term ...
A kayak is a small, narrow watercraft which is typically propelled by means of a double-bladed paddle. The word kayak originates from the Greenlandic word ''qajaq'' ().
The traditional kayak has a covered deck and one or more cockpits, each se ...
s, but also suitable for larger boat
s. The process involves securing narrow, flexible strips of wood edge-to-edge around temporary
A former is an object, such as a template, gauge or cutting die, which is used to form something such as a boat's hull. Typically, a former gives shape to a structure that may have complex curvature.
A former may become an integral part of t ...
s. The temporary formers are usually created via a process called "
Lofting is a drafting technique to generate curved lines. It is used in plans for streamlined objects such as aircraft and boats. The lines may be drawn on wood and the wood then cut for advanced woodworking. The technique can be as simple as bend ...
" whereby a set of tables is used to generate the shapes of the formers. The strips are glued edge-to-edge with epoxy. It is effectively a modern form of carvel
which needs no caulking and which is both stiffer and more watertight. In a small boat, there will be just one layer of strip-planking, but larger vessels may have two or three layers which, (being a pre-shaped marine ply
), forms a light, strong, and torsionally stiff
Monocoque ( ), also called structural skin, is a structural system in which loads are supported by an object's external skin, in a manner similar to an egg shell. The word ''monocoque'' is a French term for "single shell".
First used for boats, ...
A modern development of this construction procedure is "radius chine plywood", a method devised by yacht designer Dudley Dix
which gives a fair hull that is both light and stiff. Dix uses this boat-building method for most of his designs.
These are the most popular among boatbuilders. Some professional builders also offer both kits and finished boats. The canoes are constructed by gluing together 1/4" x 3/4" strips of wood over a building jig consisting of station molds that define the shape of the hull. The forms are cut as a series of cross-sections of the final design and set up along a "strongback" or another solid base. The strips are shaped with bead and cove router bits. Stripping begins at the sheer line and finishes with "the football", a pattern of planks at the bottom of the boat. The strips are edge-glued to each other, being held in place with nails, staples, or simply clamped to the forms. Once the strips are glued together, and the staples/nails removed, the inside and outside are sanded fair. Fiberglass and epoxy are applied to the canoe inside and out. The fiberglass covering is transparent, waterproof, and allowing the wood strips to be seen. The strips are usually cedar but can be any type of wood. Contrasting woods are sometimes used as accent strips. The last steps in construction is to install the seats, thwarts, and gunwales. Finally, a coat of marine-grade polyurethane is applied to protect the wood and epoxy from ultraviolet light.
In the 1950s, this process for building canoes and kayaks was adapted from ship/boat building techniques, and refined by a group of Minnesota canoe racers, primarily: Eugene Jensen, Irwin C.(Buzzy) Peterson, and Karl Ketter.
Strip-plank epoxy planking may be found on large yachts such as the Brady 45 catamaran
, a plans-built Australian design with Indonesian cedar planking. For a large catamaran, this construction method produces a tough hull with an inherent buoyancy. Once the strip-plank monocoque is completed, it is covered inside and out with glass fiber matting and epoxy resin. Working primarily with wood is much more pleasant for the builder than building exclusively with
Fiberglass (American English) or fibreglass (Commonwealth English) is a common type of fiber-reinforced plastic using glass fiber. The fibers may be randomly arranged, flattened into a sheet called a chopped strand mat, or woven into glass clot ...
, which can cause irritation and respiratory problems. Also, for a one-off constructor, it makes little sense to build a female mold; it is simpler and cheaper to manufacture a wooden jig that may be discarded afterward.
External linksCanoecraft: an illustrated guide to woodstrip constructionBrady 45 videoBrady catamarans homepage