Skin and Bark Boats

The earliest known boats were constructed from a frame of animal bone or light wood covered by animal skins or bark. Historians believe people used such boats as early as 16,000 bc. Several thousand years later, round skin boats, called coracles, were developed in Asia, Africa, the British Isles, and the plains of North America. Coracles have been built in Ireland in fairly recent times. They typically have a framework of woven willow shoots or other soft wood suitable for basketmaking.


Kayak
A kayaker paddles on San Francisco Bay. First used by the Inuit thousands of years ago for fishing and hunting, kayaks are widely used today for recreation. Kayaks have an enclosed deck and an open cockpit, where the rower sits with a double-bladed paddle.

Another type of skin boat is the kayak, a type of canoe created by the Inuit. The kayak is completely enclosed with animal skins stretched over a rigid frame, except for an open cockpit in the center, where the paddler sits armed with a double-bladed paddle. The kayak is wide at the center and tapers to points at both bow and stern. Kayaks in use today have much the same shape that kayaks had centuries ago, although modern kayaks may be molded from plastic, fiberglass, or Kevlar (a synthetic fiber originally developed to replace the steel in radial tires).

Bark-covered boats came into use about the same time that skin-covered boats did. They typically had a light wood frame with a bark covering made of pieces sewn together with root fiber. The frame was separated from the bark covering by a plank sheathing. Gunwales, or side edges, ran from bow to stern and provided longitudinal strength to the frame. The sheathing was held in place by forcing the ribs of the frame under the gunwales. Birchbark canoes up to 14 m (46 ft) long are known to have been built in North America. Modern canoes still have the basic shape and design of their predecessors, but they are usually molded from aluminum, plastic, fiberglass, or other lightweight, durable material.

Ancient Egyptians fashioned reed skiffs by securely binding together bundles of papyrus stems. The extreme lightness of these reed boats made them ideal for fishing in the marshes along the Nile; moreover, they were easy to carry. Equipped with sails and oars, the reed boats also carried cargo and passengers.

Wooden Boats

The earliest wooden boat, a dugout, dates from about 6000 bc and was discovered in what is now The Netherlands. A dugout consists of a log hollowed out with tools or by controlled burning. Early boat builders also constructed craft of sewn planks. This form of construction was used extensively throughout history. Sewn-timber construction was common among the peoples of the Pacific Islands, whose dugouts often had topsides formed of irregular sewn pieces of timber.


Dugout Canoes
Dugout canoes are made from hollowed-out tree trunks and thus are naturally buoyant. They may be plain or elaborately decorated like the two pictured.

Craft constructed of wood planks appear to have been developed gradually from the modified dugout by about 5000 bc, or even earlier in some regions. Log construction methods were also used for ancient Egyptian boats, in which short planks of timber were bolted edge to edge to form a hull.

Framing and planking are the basic components of modern wooden boats. The frame is used to support and stiffen the hull, including the stem, keel, keelson, ribs, knees, and wales. The planking is the outer shell that is fastened to the framing.

I. Lapstrake Construction

In northern Europe, lapstrake, or overlapping, construction was developed to a high order by the 9th century ad, particularly by the Scandinavians. Lapstrake is also known as clinch-built or clinker-built construction. Planks apparently were split off a log by means of wedges, or they were hewn and assembled on the keel, one after another beginning with the garboard, the lowest. In the Viking ships and boats of the 10th century and somewhat later, lashings were still used to secure the planks to the frames. Such construction resulted in a very flexible hull, yet one of relatively great strength. The lashings eventually were replaced by through fastenings, that is, by pegs, and later were replaced by nails driven into the planking and frames.


Viking Ship
This Viking ship, on display at the Viking Museum in Oslo, Norway, is an example of lapstrake construction. In Viking ships of the 9th century and later, external planks were overlapped and lashed to the ship’s frame, producing a strong, flexible hull.

In lapstrake construction the longitudinal seams of the planking are formed by overlapping the edges enough to allow continuous nailing. Thus, the skin, or exterior planking, adds strength to the boat. Frames are then added to give the required stiffness of form. Originally the frames were hewn of natural-crook timber, including root or limb knees and crooked trunks. Steam-bent frames became popular in the early 19th century.

II. Carvel Construction

The smooth-planked, or carvel-built, boat was developed in the Mediterranean region and was probably a natural evolution of the craft constructed of short planks bolted edge to edge used by the ancient Egyptians. Plank and frame construction was probably fully developed before ancient Greece rose to maritime prominence. As in lapstrake construction, the use of pegs probably preceded the use of metal fastenings between plank and framing.


Constructing a Wooden Whaler
Wooden ships like this 8-m (26-ft) whaler are built in stages. Because the timber must be steamed into the properly curved shapes, a fairly complex skeleton and bracing system is needed. Here, workers place horizontal planks called strakes to form the smooth curve of the hull on the starboard side of the ship.

A framing system made of almost equally spaced transverse frames fastened to a continuous keel and strengthened by a pair of gunwales running from bow to stern was a logical step in the development of smooth-planked boats. The problem of seam leakage was solved by using wood tar and caulking material, as in earlier lapstrake craft.

In so-called smooth-lap construction, developed in the 19th century, plank edges are rabbeted, or shaped, so that they lap and still remain smooth at the seams; the rabbeted laps are nailed in the usual lapstrake manner. See Woodworking: Carpentry.

In the early 20th century the use of lapstrake construction decreased, while carvel construction became more popular. The shift was caused largely by the need for extreme structural strength necessitated by the use of motors in small boats. Carvel construction also better met the demand for fast sailing craft used for racing.

III. Plywood Construction

Plywood boat construction began in the United States about 1918 and developed rapidly; the two basic types are paneled and molded. Panel construction involves securing flat sheets of plywood to transverse frames and to the keel and other units that supply longitudinal strength; it is used only with chine-model boats, that is, those with flat bottoms or V-bottoms. The amount of compound curve that may be used in a plywood panel is extremely limited.


Fishing in Newfoundland and Labrador
Plywood panel boats are flat-bottomed, a hull shape that lends itself well to fishing. Here, workers on a fishing boat haul a fish trap aboard off the coast of Cape Spear, the easternmost point in North America.

In molded-plywood construction the form of the boat is established by temporary transverse frames, or molds, and by longitudinal battens (thin, narrow strips of lumber often used to seal or reinforce joints), over which the planking is placed in two or three layers. The first skin is laid on diagonally and secured to the form by staples. Two or three skins are used, and after stapling, the mold is moved into a heating and pressure stage in which adhesion of the skins is accomplished. After adhesion, stiffeners and joinery are added; these usually include keelson, shoe, gunwale, guards, thwarts, decking, outside stem, transom (in a square-stern boat), and centerboard case and mast step (in a sailing hull).

Canvas-Covered Boats

In the construction of canvas-covered small boats, very thin planking is laid over light steam-bent frames; then canvas is stretched tightly over the hull by clamps and a tackle at bow and stern. After the canvas is secured, it is coated with a thin primer or is first wetted with water. The canvas shrinks as it dries, making a smooth surface. The canvas is then painted, outside guards are fitted at the gunwales, and an external keel and stempost and sternpost are fitted. The result is a light and tight boat suited for easy carrying and occasional use.

Aluminum Boats

The first aluminum boats built in the United States were for the polar expedition of American journalist and explorer Walter Wellman in 1894, although the first known use of aluminum was in Europe in 1891. After World War II (1939-1945), aluminum boats became common, usually in the form of canoes or simple craft used for sport fishing. These boats are built from sheets of aluminum, perhaps given curvature by stamping, and are fastened together with rivets. Sandwich-type constructions, intended to increase both lightness and strength, are under development.

Ferrocement Boats

Ferrocement, a closely spaced wire mesh made watertight by plastering of concrete, has some advantage for boats that must be built in small numbers by unskilled workers without sophisticated tools. Waterproof cloth can be formed into boat-shaped bags, which are then inflated to make small craft that are suitable and popular for some uses.