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Canoe

From Academic Kids

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Canoe.jpg
Canoe at El Nido, Philippines

A canoe is a relatively small human-powered boat. Canoes are pointed at both ends and usually open on top.

It is propelled by the use of paddles, with the number of paddlers depending on the size of canoe. Paddlers face in the direction of travel, either seated on supports in the hull, or kneeling directly upon the hull. In this way paddling a canoe can be contrasted with rowing, where the rowers face away from the direction of travel. Paddles may be single-bladed or double-bladed.

Contents

Ambiguity over the word Canoe

Confusingly, the sport of canoeing, organised at the international level by the International Canoe Federation, uses the word canoe to cover both canoes as defined here, and kayaks (see below for a brief description of the differences between a kayak and a canoe). In fact, the sport of canoe polo is exclusively played in kayaks. This confusing use of canoe to generically cover both canoes and kayaks is not so common in North American usage, but is common in Britain, Australia and presumably many parts of the world, both in sporting jargon and in colloquial speech. In these circumstances, the canoe as defined here is sometimes referred to as an open, Canadian, or Indian canoe, though these terms have their own ambiguities.

A 'canoe' in this ambiguous sense is a paddled vessel in which the user faces the direction of travel.

Design and construction

Canoe materials

  • Many early canoes were wooden, often simply hollowed-out tree trunks. This technology is still practiced in some parts of the world.
  • Modern wooden canoes are typically strip-built by woodworking crafstmen. Such canoes can be very functional, lightweight, and strong, and are frequently quite beautiful works of art.
  • Birch bark and a mixture of tar and tree sap were used by the American Indians of temperate North America, and later became the standard form of transport for Voyageurs of the fur trade.
  • Wood-and-Canvas canoes are made by fastening an external canvas shell to wooden ribbing. These use of canvas for this purpose was invented by Union scouts during the United States Civil War.
  • Aluminum canoes were popularized by the Grumman company in 1944, when demand for airplanes for World War II began to drop off. Aluminum allowed a lighter and much stronger construction than contemporary wood technology. However, aluminium is denser than water, so a capsized aluminium canoe will sink unless the ends are filled with flotation devices.
  • Royalex is a modern composite material that makes an extremly flexible and durable hull. Royalex canoes have been known, after being wrapped around a tree, to be popped back into their original shapes with minimal creasing of the hull.
  • Fiberglass and Kevlar are also used for canoe construction.

Depending on the intended use of a canoe, the various kinds have different advantages. For example, a canvas canoe is more fragile than an aluminum canoe, and thus less suitable for use in rough water; but it is quieter, and so better for observing wildlife. However, canoes made of natural materials require regular maintenance, and are lacking in durability.

Hull design considerations

A rounded-bottom canoe exhibits poor resistance to small degrees of tilt, but is difficult to overturn (i.e. its initial stability is lacking, but its final stability is good). A flat-bottomed canoe has excellent initial stability, but if tilted beyond a threshold, becomes unstable and will capsize. Round-bottomed designs are also able to go over obstructions much more easily, due to a small area of contact with the obstruction, though they do have a slightly greater draft.

Keels on canoes increase the ability to track in a straight line with crosswind, but decrease the ability to turn quickly to avoid an obstacle. "Vee"-bottom canoes have an integrated keel-like protrusion of the hull, which increases initial stability. Some sort of keel is beneficial when traveling on open water with crosswinds, but the associated increase in draft is undesirable for whitewater.

Keels don't really appreciably help canoes go in a straight line. Canoes are displacement craft. Their hull, moving through the water, is much larger than the keel alone, and has considerably more effect on a canoes path through the water. In aluminum canoes, keels are manufacturing artifacts, where two halves of a hull are joined. In wood-and-canvas canoes, keels are rub-strips to protect the boat from rocks and as they are pulled up on shore. Plastic canoes feature keels for stiffening the hull and allowing internal tubular framing to be flush with the sole of the canoe. Hull shape, particularly the degree to which the hull is fine fore and aft, and rocker, determine how well (or not) a canoe tracks. Oh, and paddling technique.

Rounded-end canoes are able to turn easily. Angled-end canoes are somewhat resistant to turning, but have greater tracking ability. Tall ends serve little purpose other than catching the wind.

Canoe hulls are generally open on top. However, slalom canoes are closed in with a spraydeck, like many kayaks.

Traditional designs around the world

Early canoes in many parts of the world were dugout canoes, formed of hollowed logs.

In the Pacific Islands, dugout canoes are fitted with outriggers for increased stability in the ocean. These canoes can be very large, and were once used for long-distance travel. In Hawaii, canoes are traditionally manufactured from the trunk of the koa tree. They typically carry a crew of six: one steersman and five paddlers.

In the temperate regions of North America, canoes were traditionally made of a wood frame covered with bark of a birch tree, pitched to make it waterproof. Later, they were made of a wooden frame, wood ribs, other wood parts (seats, gunwales, etc.) and covered with canvas, sized and painted for smoothness and watertightness.

The parts of a canoe

View of a typical canoe from above
  1. Bow
  2. Stern
  3. Hull
  4. Seat
  5. Thwart (a horizontal crossbeam near the top of the hull)
  6. Gunwale (pronounced gunnel; the top edge of the hull)
  7. Deck (a compartment containing a foam block which prevents the canoe from sinking if capsized)

Use

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Dugout_canoe.jpg
A dugout canoe in the Solomon Islands

Canoes have a reputation for instability, but this is not true if they are handled properly. For example, the occupants need to keep their center of gravity as low as possible. Canoes can navigate swift-moving water with careful scouting of rapids and good communication between the paddlers.

When two people occupy a canoe, they paddle on opposite sides. For example, the person in the bow (the bowman) might hold the paddle on the port side, with the left hand just above the blade and the right hand at the top end of the paddle. The left hand acts mostly as a pivot and the right arm supplies most of the power. Conversely, the sternman would paddle to starboard, with the right hand just above the blade and the left hand at the top. For travel straight ahead, they draw the paddle from bow to stern, in a straight line parallel to the gunwale.

Steering

The paddling action of two paddlers will tend to turn the canoe toward the opposite side that on which the sternman is paddling. Thus, steering is particularly important, particularly because canoes have flat-bottomed hulls and are very responsive to turning actions. Steering techniques vary widely, even as to the basic question of which paddler should be responsible for steering.

Among experienced white water canoeists, the sternman is primarily responsible for steering the canoe, with the exception of two cases. The bowman will steer when avoiding rocks and other obstacles that the sternman cannot see. Also, in the case of backferrying, the bowman is responsible for steering the canoe using small correctional strokes while backpaddling with the sternman.

Among less-experienced canoeists, the canoe is typically steered from the bow. The advantage of steering in the bow is that the bowman can change sides more easily than the sternman. Steering in the bow is initially more intuitive than steering in the stern, because to steer to starboard, the stern must actually move to port. On the other hand, the paddler who does not steer usually produces the most forward power or thrust, and the greater source of thrust should be placed in the bow for greater steering stability.

Paddle strokes

  • Advocates of steering in the stern often use the J-stroke, which is so named because, when done on the port side, it resembles the letter J. It begins like a standard stroke, but towards the end, the paddle is rotated and pushed away from the canoe with the power face of the paddle remaining the same throughout the stroke. This conveniently counteracts the natural tendency of the canoe to steer away from the side of the sternman's paddle. This stroke is used in reverse by the bowman while backpaddling or backferrying in white water.
  • A less elegant but more effective stroke which is used in the stern is the Superior stroke, more commonly referred to as the goon or rudder stroke. Unlike the J-stroke in which the side of the paddle pushing against the water during the stroke (the power face) is the side which is used to straighten the canoe, this stroke uses the opposite face of the paddle to make the steering motion. It is somewhat like a stroke with a small pry at the end of it. This stroke uses larger muscle groups, is preferable in rough water and is the one used in white water. It is commonly thought to be less efficient than the J-stroke when paddling long distances across relatively calm water.
  • Another stroke which may be used by either the bow or stern paddler is the pry stroke. The paddle is inserted vertically in the water, with the power face outward, and the shaft braced against the gunwale. A gentle prying motion is applied, forcing the canoe in the opposite direction of the paddling side.
  • The running pry can be applied while the canoe is moving. As in the standard pry, the paddle is turned sideways and braced against the gunwale, but rather than forcing the paddle away from the hull, the paddler simply turns it at an angle and allows the motion of the water to provide the force.
  • The draw stroke exerts a force opposite to that of the pry. The paddle is inserted vertically in the water at arm's length from the gunwale, with the power face toward the canoe, and is then pulled inward to the paddler's hip. A draw can be applied while moving to create a running or hanging draw.
  • The cross-draw stroke is a bowman's stroke that exerts the same vector of force as a pry, by moving the blade of the paddle to the other side of the canoe without moving the paddler's hands. The arm of bottom hand crosses in front of the bowman's body to insert the paddle in the water on the opposite side of the canoe some distance from the gunwale, facing towards the canoe, and is then pulled inward while the top hand pushes outward. The cross-draw is much stronger than the draw stroke.
  • The sweep is unique in that it steers the canoe away from the paddle regardless of which end of the canoe it is performed in. The paddle is inserted in the water some distance from the gunwale, facing forward, and is drawn backward in a wide sweeping motion. The paddler's bottom hand is choked up to extend the reach of the paddle. In the case of the bowman, the blade will pull a quarter-circle from the bow to the paddler's waist. If in the stern, the paddler pulls from the waist to the stern of the canoe. Backsweeps are the same stroke done in reverse.

Complementary strokes are selected by the bow and stern paddlers in order to safely and quickly steer the canoe. It is important that the paddlers remain in unison, particularly in white water, in order to keep the boat stable and to maximize efficiency.

There are some differences in techniques in how the above strokes are utilized.

  • One of these techniques involves locking or nearly locking the elbow, that is on the side of the canoe the paddle is, to minimize muscular usage of that arm to increase endurance. Another benefit of this technique is that along with using less muscle you gain longer strokes which results in an increase of the power to stroke ratio. This is generally used more with the 'stay on one side' method of paddling.
  • The other technique is generally what newer canoeists use and that is where they bend the elbow to pull the paddle out of the water before they have finished the stroke. This is generally used more with the 'it is ok to switch sides' method of paddling.
  • The Stay on one side method is where each canoeist takes opposite sides and the sternman uses occasional J-strokes to correct direction of travel.
  • The It is ok to switch sides method is a where the canoeists are constantly switching sides to maintain their heading. Each time they switch sides though, their canoe slows down during the pause, so generally these canoeists are slower.
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Canoe1572.jpg

Setting poles

On swift rivers, the sternman may use a setting pole. It allows the canoe to be move through water too shallow for a paddle to create thrust, or against a current too quick for the paddlers to make headway. With skillful use of eddies, a setting pole can propel a canoe even against moderate (class III) rapids.

Similar boats

  • The main difference between a kayak and a canoe is that a kayak is a closed canoe meant to be used with a double-bladed paddle, one on each end, instead of a single bladed paddle. The double-bladed paddle makes it easier for a single person to handle a kayak. Kayaks are more commonly enclosed on top with a deck, making it possible to recover from a capsize without the kayak filling with water, although there are also closed canoes, which are common in competition. The deck is an extension of the hull, with a special sheet called a spraydeck sealing the gap between deck and the paddler.
  • A rowboat is not really like a canoe, since it is propelled by oars resting in pivots on the gunwales. A single rower works 2 oars, and sits with his or her back toward the direction of travel. Some rowboats, such as a River Dory or a raft outfitted with a rowing frame are suitable for whitewater.
  • The outrigger canoe consists of a hull and a secondary floating support.
  • The Adirondack guideboat is a rowboat that has similar lines to a canoe. However the rower sits closer to the bilge and uses a set of pinned oars to propel the boat.

External links

References

da:Kano (bd) de:Kanu bg:Кану es:Canoa fr:Cano it:Canoa ja:カヌー nl:Kano pl:kanadyjka (łdź) fi:Kanootti sv:kanadensare

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