E L E M E N T S O F C A N O E D E S I G N
The dimensions and shape of a canoe define its performance. Every canoe design blends innumerable variables to produce a canoe with specific characteristics such as stability for birding, manoeuvrabil- ity for whitewater or speed for marathon racing. Complicated? On a designer’s drafting table, yes. The basics, however, are not.
DIMENSIONS Length, width and depth are the rough indicators of a canoe’s speed, sta- bility, capacity and seaworthiness. Changing any of these dimensions will affect performance.
LENGTH = SPEED: Length is the primary factor in determining speed. Given two canoes of different lengths, with all other specifications being the same, the longer canoe will be faster. It will also track better (travel in a straight line) and carry more gear. Shorter canoes will be lighter and more manoeuvrable.
WIDTH = STABILITY: The boat’s width and cross-sectional shape are the pri- mary determinants of stability. A wider canoe will generally be more stable. Wide canoes offer great stability but also present greater resistance to the water. Narrow canoes may be less stable, but are more efficient and faster.
DEPTH = CAPACITY AND DRYNESS: The amount of depth influences the freeboard—the distance between the waterline and the gunwales. Great- er depth allows for increased carrying capacity and better water-shedding ability. Deeper canoes, however, can be harder to handle in windy condi- tions and will be heavier.
LxWxD = CARRYING CAPACITY: Taken together, the basic dimensions add up to a canoe’s volume—the total amount of internal space. Carrying capacity is measured in different ways, but typically refers to how much weight the boat is able to hold while maintaining at least six inches of freeboard. Carrying capacity can be increased by making the boat wider, longer or deeper. Widening without adjusting the length increases drag, reducing efficiency. Increasing the length is usually the best overall solu- tion, while increasing the depth can help as well. This is why cargo-haul- ing tripping boats are long and deep but not excessively wide.
SHAPE Canoe performance is mainly de- termined by hull shape. Front, side and overhead views of the boat give you cross-section, rocker, hull symmetry and taper.
CROSS-SECTION—INITIAL AND SECONDARY STABILITY
FOUR ELEMENTS OF CANOE SHAPE Rocker
Sides
HEAVY MODERATE STRAIGHT
Hull Symmetry
ASYMMETRICAL SYMMETRICAL
TUMBLEHOME FLAT FLARE Most canoe designs are a compromise between flat and round, with
shallow-arch or shallow-V bottoms. These designs sacrifice varying degrees of initial stability for good secondary stability and all-around performance. The cross-section of some canoes is modified by the addition of a keel. A
keel is a ridge that runs the length of the canoe on the bottom of the boat to help the canoe track and resist the influence of crosswinds. Keels are most often found on short, wide canoes used for recreation and sporting. They are undesirable in whitewater because they reduce manoeuvrability and can become snagged on rocks. The sides of the canoe are either flared, turned-in or straight. Flared sides
shed water. Tumblehome describes the shape of a canoe with turned-in sides. Tumblehome results in a narrower beam at the gunwales making it easier for the paddler to reach over the side of the canoe when paddling. Straight-sided canoes are a balance between the paddling efficiency of tumblehome and the dryness of flare. Canoe designs will incorporate one, two, or all three of these in different areas of the hull.
ROCKER—TRACKING VS. MANOEUVRABILITY Viewed from the side, the amount that the canoe’s keel line curves upward toward the bow and stern is termed rocker. The amount of rocker deter- mines how easily a boat turns versus how well it tracks. A straight keel line (no rocker) allows for exceptional tracking, ideal for covering long distances in a straight line. A canoe with a lot of rocker offers exceptional manoeuvrability.
HULL SYMMETRY AND TAPER Viewed from above, symmetrical canoes have identical bow and stern ends with the widest point at the centre of the hull. This design offers more versatility because it can be paddled as a tandem or a solo canoe. Asym- metrical canoes typically have the widest section behind the centre of the boat creating a longer bow. This produces enhanced forward speed and tracking and is often seen in touring and performance boat designs. Tour- ing and performance boats will also have sharper tapers at the bow and stern to cut through the water efficiently. Whitewater and general-purpose boats will have blunter ends to add volume and give buoyancy in waves.
Bottom ROUND Trimming GUNWALES STRAIGHT SHALLOW ARCH
CONTOURED YOKE THWART
SEAT DECK
The cross-sectional shape of the bottom and sides of the canoe will influence its performance, especial- ly its stability. Stability is divided into initial (primary) and final (secondary). Initial stability is what you feel when you first get into the boat. In a boat
with great initial stability, you can stand up and walk around. It takes a lot of effort to flip this boat on flatwater. It resists leaning until it reaches a point of no return, beyond which it quickly upsets. That’s because second- ary stability was sacrificed for the stable platform providing initial stability. Secondary stability refers to how the boat behaves as it tilts. A boat with
great secondary stability feels stable and predictable when on a lean. This is a useful characteristic for whitewater, rough-water paddling and soloing. Flat-bottomed canoes offer great initial stability at the expense of speed
and rough-water performance. Since they are secure on calm water, they’re great for sportsmen and recreational paddlers. Round-bottomed boats are the other end of the spectrum. Perfectly
rounded bottoms allow for clean entry and exit lines and minimal surface area in the water. They have great speed and efficiency but virtually no initial stability. This is why rowing shells are round-bottomed.
MATERIALS Once you have chosen a canoe design that best suits your needs, your choice of material will be based on durability, cost, weight, aesthetics, and the shape require- ments of the canoe. There is a staggering number of
different materials used to make ca- noes including wood (sealed with canvas or fibreglass), polyethylene plastic, Royalex, and composites (glass, Kevlar or carbon/graphite fi- bres mixed with adhesive resins).
Strong, lightweight composites such as Kevlar are good for trippers, rac- ers or anyone else willing to spend money to shave off pounds. Heavier Royalex boats are favoured by whitewater paddlers primarily
concerned with bumping, bouncing, sliding and bending over rocks un- scathed. Royalex, a supple vinyl-and-foam sandwich that looks like plas- tic and bounces back to shape when deformed, is also well-suited to the round, blunt shapes of most whitewater designs. Wood canoes—expensive once the craftsmanship is factored in—are in
a class of their own. Though relatively fragile and not exceptionally light- weight, wood boats excel in beauty. Less expensive materials like fibreglass and polyethylene are used in a
variety of boats for a wide range of purposes. In the simplest terms, these materials share the advantages of their higher-end cousins—composite for lightness, plastic for durability. Finally, many manufacturers have their own versions or combinations of these materials, proprietary constructions with trademarked names.—Eds
C ANOE ROOT S n 1 9
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52 |
Page 53 |
Page 54 |
Page 55 |
Page 56 |
Page 57 |
Page 58 |
Page 59 |
Page 60 |
Page 61 |
Page 62 |
Page 63 |
Page 64 |
Page 65 |
Page 66 |
Page 67 |
Page 68