| A wide variety of materials and materials are | | | | These can be solid fiberglass or of the |
| used in boat building: | | | | sandwich (cored) type, in which a core of |
| | | | balsa, foam or similar material is applied |
| Wood - The traditional boat building material | | | | after the outer layer of fiberglass is laid |
| that was and is still used for hull and spar | | | | to the mold, but before the inner skin is |
| construction. It is buoyant, cheap, widely | | | | laid. This is similar to the next type, |
| available and easily worked. It is not | | | | composite, but isn't usually classified as |
| particularly abrasion resistant and it can | | | | composite, since the core material in this |
| deteriorate if fresh water or marine | | | | case doesn't provide much additional |
| organisims are allowed to penetrate the wood. | | | | strength. It does, however, increase |
| Rot resistant woods such as cedar and oak are | | | | stiffness, which means that less resin and |
| generally selected for wooden boat | | | | fiberglass cloth can be used in order to save |
| construction. Glue, screws and/or nails are | | | | weight. Most fiberglass boats are currently |
| used to join the wooden components. Some | | | | made in an open mold, with fiberglass and |
| types of wood construction include: | | | | resin applied by hand. Some are now |
| | | | constructed by vacuum infusion where the |
| Carvel, in which a smooth hull is formed by | | | | fibers are laid out and resin is pulled into |
| wooden planks attached to a frame. The planks | | | | the mold by admospheric pressure. This can |
| may be curved in cross section like barrel | | | | produce stronger parts with more glass and |
| staves. Carvel planks are generally caulked | | | | less resin, but takes special materials and |
| with oakum or cotton that is driven into the | | | | more technical knowledge. |
| seams between the planks and covered with | | | | |
| some water proof substance. It takes its name | | | | Composite - While GRP, wood, and even |
| from an archaic ship type and is believed to | | | | concrete hulls are technically made of |
| have originated in the Mediterranian. | | | | composite materials, the term "composite" is |
| | | | often used for plastics reinforced with |
| Another method of building wooden boats is | | | | fibers other than (or in addition to) glass. |
| lapstrake, a technique originally identified | | | | Cold-molded refers to a type of building |
| with the Vikings in which wooden planks are | | | | one-off hulls using thin strips of wood |
| fixed to each other with a slight overlap | | | | applied to a series of forms at 45-degree |
| that is beveled for a tight fit. The planks | | | | angles to the centerline. This method is |
| may be mechanically connected to each other | | | | often called double-diagonal because a |
| with copper rivets, bent over iron nails, | | | | minimum of two layers is recommended, each |
| screws or with adhesives. Often, steam bent | | | | occurring at opposing 45-degree angles. |
| wooden frames are fitted inside the hull. | | | | "Cold-molding" is now a relatively archaic |
| This technique is known as clinker in Britain | | | | term because the contrasting "hot-molded" |
| and also as clench built. | | | | method of building boats, which used ovens to |
| | | | heat and cure the resin, has not been widely |
| Another method uses sheets of plywood panels | | | | used since WWII. Now almost all curing is |
| fixed to a frame. Plywood may be laminated | | | | done at room temperature. Other composite |
| into a round hull or used in single sheets. | | | | types include sheathed-strip, which uses |
| These hulls generally have one or more | | | | (usually) a single layer of strips laid up |
| chines. A type of the plywood panel boat | | | | parallel to the sheer line. The composite |
| building methond is known as the | | | | materials in question are then applied to the |
| stitch-and-glue method, where pre-shaped | | | | mold in the form of a thermosetting plastic |
| panels of plywood are edge glued and | | | | (usually epoxy, polyester, or vinylester) and |
| reinforced with fibreglass without the use of | | | | some kind of fiber cloth (fiberglass, kevlar, |
| a frame. Metal or plastic wires pull curved | | | | dynel, carbon fiber, etc), hence the finished |
| flat panels into three dimensional curved | | | | hull is a "composite" of fiber and resin. |
| shapes. These hullls generally have one or | | | | These methods often give strength-to-weight |
| more chines. | | | | ratios approaching that of aluminum, while |
| | | | requiring less specialized tools and skills. |
| Steel (and before that iron) - Either used in | | | | |
| sheet for all-metal hulls or for isolated | | | | Steel-reinforced cement (ferrocement) - |
| structural members. It is strong, but heavy. | | | | Strong and long lasting. First developed in |
| The material rusts unless protected from | | | | the mid 19th Century in France. Used for |
| water. Modern steel components are welded or | | | | building warships during the war. Extensively |
| bolted together. Until the mid 1900s, steel | | | | refined in New Zealand shipyards in the 1950s |
| sheets were riveted together. | | | | and the material became popular among amateur |
| | | | builders of cruising sailboats in the 1970s |
| Aluminium - either used in sheet for | | | | and 1980s, because the material cost was |
| all-metal hulls or for isolated structural | | | | cheap although the labour time element was |
| members. Many sailing spars are made of | | | | high. The weight of a finished ferro-cement |
| aluminium. The material requires special | | | | boat is comparable to that of a traditionally |
| manufacturing techniques, construction tools | | | | built wooden boat. As such they are often |
| and construction skills. While it is easy to | | | | built for slower, more comfortable sea |
| cut, aluminium is difficult to weld, and also | | | | passages. Hulls built properly of ferrocement |
| requires heat treatments such as | | | | are more labor-intensive than steel or |
| precipitation strengthening for most | | | | fiberglass, so there are few examples of |
| applications. Corrosion is a concern with | | | | commercial ship-yards using this material. |
| aluminium, particularly below the waterline. | | | | The inability to mass produce boats in ferro |
| | | | cement has led there to being few examples |
| Fiberglass (Glass-reinforced plastic or GRP) | | | | around. Many ferrocement boats built in back |
| - Typically used for production boats because | | | | yards have a rough, lumpy look, which has |
| of its ability to reuse a female mold as the | | | | helped to give the material a poor |
| foundation for the shape of the boat. The | | | | reputation. The ferro-cement method is easy |
| resulting structure is strong in tension but | | | | to do, but it is also easy to do wrong. This |
| often needs to be either laid up with many | | | | has led to some disastorous 'home-built' |
| heavy layers of resin-saturated fiberglass or | | | | boats. Properly designed, built and plastered |
| reinforced with wood or foam in order to | | | | ferrocement boats have smooth hulls with fine |
| provide stiffness. GRP hulls are largely free | | | | lines, and therefore are often mistaken for |
| of corrosion though not normally fireproof. | | | | wooden or fiberglass boats. |