The International Canoe has only had rigid hull design restrictions since 1971. The old international rules, constituted in 1933, allowed for experimentation in design within a variance of one foot in length and six inches in width. A "rise of floor" rule was necessary to discourage the extreme vee bottoms that were so detrimental to the decked sailing canoe's popularity in North America in the late 1880s and 1890s.
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RulesDesigns that have been builtSpecs and DrawingsMy own designs
Dimensions:
Length and Beam:
Length (excluding rudder fittings): Maximum 5.20 m. (17 ft. 3/4 in). Minimum 4.875 m (16 ft.). At widest point, beam to be not less than 0.95 m. (37-3/8 ins.) nor more than 1.1 m. (43-1/4 in.).
Rise of Floor:
At midlength, 0.102 m (4 ins.) above underside of skin at centerline, or side of centerboard slot at skin line, the beam shall not be less than 0.813 m. (32 ins.).
Depth of Body:
At midlength, the depth from the underside of skin at centerline, or from the side of centerboard slot at skin line, to the gunwale height shall not be less than 5.5% of length overall. If the position of the gunwale in not obvious, the measuring poiint is defined as the highest point existing between the maximum beam and a point 2 inches inboard. The maximum depth of canoe including deck shall not exceed 0.559 m. (22 ins.). The foredeck shall be convex. The measurement of beam, rise of floor and body depth are to be taken to the skin line at the outside of the skin, excluding rubbing bands, bilge keels or other additions to the skin, as well as local hollows.
Shape:
The horizontal projection of the line of outside gunwale or line of greatest beam, where ever found shall be a fair convex curve and at bow and stern shall lie inside a line which is 45 degrees to the centerline and meets the centerline not more than 1.27 cm. (1/2 in.) beyond the extremity of stem and sternposts, respectively. The sheer shall be a straight line or a fair, continuous concave curve. No steps shall be allowed in the skin.
Weight:
The minimum stripped hull weight shall not be less than length overall times beam times K. (Where length over-all and beam are in feet, and weight is in pounds, K equals 2.4; in meters, and weight in kilograms, K equals 11.72.)
Stripped hull means the hull of the canoe without centerboard, centerboard tackle or winch, rudder, rudder-frame, tiller, masts, spars sails, standing or running rigging, winches deck seat, bottom boards and other loose equipment, but may include hatch covers, tiller posts, cleats, stayplates, fairleads, horse, tabernacle, stem, stern and keel attachments, the decision of the Official Measurer shall be final.
Other Measurements:
All other measurements and specifications shall be those specified for the International Decked Sailing Canoe published by the International Canoe Federation.
National Designs That Have Been Built
There are many designs which were designed prior to 1970/71 when the Nethercott was chosen as the standardized IC hull shape. Uffa Fox, Peter Nethercott and Ian Proctor in the UK and Lou Whitman in the US were the predominant pre-standardization designers. As well a Swedish single chine, called SLURP, was designed by Martin Rossell and three were built just prior to standardization.
Of those, I believe, only Lou Whitman's designs have been built as National Canoes. Bob Ames, an Annapolis designer, also designed a multi-chine of which there have been two built (both by John Williamson - USA). Ames also was able to take off measurements from Rossell's SLURP design and produce lines drawings using CAD software. Bill Beaver (USA) started from the Ames drawings and produced lines from which "Lust Puppet" was built. John Williamson also built a Beaver single chine but modified it in building to give it more of an arch bottom/ less slab-sided look. Ted Causey (USA) has built several Lou Whitman designs and a single chine, "Christie", of his own design. In 1999/2000 Bill Beaver and John Williamson collaborated on designing a double chine being currently built by John Williamson.
During the 1980s, Ted Causey pulled many NCs from the Pheonix mold he bought from Lou Whitman. Apparently many of these were under the weight limit and hence illegal though one can always modify a Causey Pheonix to race legally. It has been many years though since a hull has been made from that mold. More recently, Ted built two Whitman chine NCs (inspired by BIll Beaver's excellent hull survey and analysis article in the May '96 Canoesletter - Vol. 18 #2 & supporting graphics).
National Canoe Designs - Specs and Drawings
Below are as many NC designs as I have lines drawings for or information about (not all have lines drawings). I don't have tables of offsets but I hope to be able to provide them for some of the designs. Currently the pages just have drawings. In time I'll add text.
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Off The Beaten Track - My Own NC Designs Using Hullform Software
Hull design is a bit of a fascination with me. I love pouring over lines drawings and reading books about boats, their design and construction. At times it becomes almost an obsession. I must qualify my interest here - I'm strictly amateur. I don't have professional training in engineering or naval architecture nor do I pretend to be an expert. As well, I'm very open to criticism - please tell me what I did wrong.
I've designed a slew of NCs using a program called Hullform by Blue Peter Marine. I hope to post the drawings, specs and offsets of many of my designs here. My aim in many of the designs is to design a cheap, stitch & glue, plywood National Canoe. Other designs are smooth hulls with flat planing bottoms or vee'd bottoms; designs that exploit the rules like extreme assymetrical canoes with the sharpest bows and fullest sterns possible; boats with parallel sides and lots of flare to maximize stability and ease of use; etc. Any theory I have or read about I'll try it out on an NC hull.