Boat building is the design and construction of boats and their systems. This includes at a minimum a hull, with propulsion, mechanical, navigation, safety and other systems as a craft requires.
Wood is the traditional boat building material used for hull and spar construction. It is buoyant, widely available and easily worked. It is a popular material for small boats (of e.g. 6-metre (20 ft) length; such as dinghies and sailboats). Its abrasion resistance varies according to the hardness and density of the wood and it can deteriorate if fresh water or marine organisms are allowed to penetrate the wood. Woods such as Teak, Totara and some cedars have natural chemicals which prevent rot whereas other woods, such as Pinus radiata, will rot very quickly. The hull of a wooden boat usually consists of planking fastened to frames and a keel. Keel and frames are traditionally made of hardwoods such as oak while planking can be oak but is more often softwood such as pine, larch or cedar.
Plywood is especially popular for amateur construction but only marine ply using waterproof glues and even laminates should be used. Cheap construction plywood often has voids in the interior layers and is not suitable to boat building as the voids trap moisture and accelerate rot as well as physically weaken the plywood. No plywood is rot resistant and should be coated with epoxy resin and/or a good paint system. Varnish and Linseed oil should not be used on the exterior of a hull for waterproofing. Varnish has about 60% of the water resistance of a good paint system. Only boiled linseed oil should be used on a boat and only in the interior as it has very little water resistance but it is very easy to apply and has a pleasant smell. Note that used linseed rags should not be left in a pile as they can catch fire. A valuable 200-year-old waka (Maori canoe) caught fire in New Zealand in June 2014 when restorers left rags piled overnight. Raw linseed oil is not suited to boats as it stays damp and oily for a long time. Mildew will grow well on raw linseed oil treated timber but not on boiled linseed oil. More recently introduced tropical woods as mahogany, okoumé, iroko, Keruing, azobé and merbau.are also used. With tropical species, extra attention needs to be taken to ensure that the wood is indeed FSC-certified. Teak or iroko is usually used to create the deck and any superstructure. Glue, screws, rivets and/or nails are used to join the wooden components. Before teak is glued the natural oil must be wiped off with a chemical cleaner, otherwise the joint will fail.
Traditional wood construction techniques can be classified into the "shell-first" method (also called "planking first") and the "frame first" method. With "shell first", the form of the hull is determined by joining shaped planks that are fastened together, followed by reinforcing the structure with the frames (or ribs) that are fitted to the inside. With "frame first", the hull shape is established by setting up the frames on the keel and then fastening the planking on the outside. : 8
Some types of wood construction include:
Either used in sheet or alternatively, platefor all-metal hulls or for isolated structural members. It is strong, but heavy (despite the fact that the thickness of the hull can be less). It is generally about 30% heavier than aluminium and somewhat more heavy than polyester. The material rusts unless protected from water (this is usually done by means of a covering of paint). Modern steel components are welded or bolted together. As the welding can be done very easily (with common welding equipment), and as the material is very cheap, it is a popular material with amateur builders. Also, amateur builders which are not yet well established in building steel ships may opt for DIY construction kits. If steel is used, a zinc layer is often applied to coat the entire hull. It is applied after sandblasting (which is required to have a cleaned surface) and before painting. The painting is usually done with lead paint (Pb3O4). Optionally, the covering with the zinc layer may be left out, but it is generally not recommended. Zinc anodes also need to be placed on the ship's hull. Until the mid-1900s, steel sheets were riveted together.
Aluminum and aluminum alloys are used both in sheet form for all-metal hulls or for isolated structural members. Many sailing spars are frequently made of aluminium after 1960. It is the lightest material for building large boats (being 15–20% lighter than polyester and 30% lighter than steel). Aluminium is relatively cheap in comparison with wood or steel in most countries. In addition it is relatively easy to cut, bend and weld. Galvanic corrosion below the waterline in salt water is a serious concern, particularly in marinas where there are other conflicting metals. Aluminium is most commonly found in yachts, pontoon and power boats that are not kept permanently in the water. Aluminium yachts are particularly popular in France.
A relatively expensive metal used only very occasionally[ why? ] in boatbuilding is cupronickel. Arguably the ideal metal for boat hulls, cupronickel is reasonably tough, highly resistant to corrosion in seawater, and is (because of its copper content) a very effective antifouling metal. Cupronickel may be found on the hulls of premium tugboats, fishing boats and other working boats; and may even be used for propellers and propeller shafts.
Fiberglass (glass-reinforced plastic or GRP) is typically used for production boats because of its ability to reuse a female mould as the foundation for the shape of the boat. The resulting structure is strong in tension but often needs to be either laid up with many heavy layers of resin-saturated fiberglass or reinforced with wood or foam in order to provide stiffness. GRP hulls are largely free of corrosion though not normally fireproof. These can be solid fiberglass or of the sandwich (cored) type, in which a core of balsa, foam or similar material is applied after the outer layer of fiberglass is laid to the mould, but before the inner skin is laid. This is similar to the next type, composite, but is not usually classified as composite, since the core material in this case does not provide much additional strength. It does, however, increase stiffness, which means that less resin and fiberglass cloth can be used in order to save weight. Most fibreglass boats are currently made in an open mould, with fibreglass and resin applied by hand (hand-lay-up method). Some are now constructed by vacuum infusion where the fibres are laid out and resin is pulled into the mould by atmospheric pressure. This can produce stronger parts with more glass and less resin, but takes special materials and more technical knowledge. Older fibreglass boats before 1990 were often not constructed in controlled temperature buildings leading to the widespread problem of fibreglass pox, where seawater seeped through small holes and caused delamination. The name comes from the multitude of surface pits in the outer gelcoat layer which resembles smallpox. Sometimes the problem was caused by atmospheric moisture being trapped in the layup during construction in humid weather.
"Composite construction" involves a variety of composite materials and methods: an early example was a timber carvel skin attached to a frame and deck beams made of iron. Sheet copper anti-fouling ("copper=bottomed") could be attached to a wooden hull provided the risk of galvanic corrosion was minimised. Fast cargo vessels once were copper-bottomed to prevent being slowed by marine fouling. GRP and ferrocement hulls are classic composite hulls, the term "composite" applies also to plastics reinforced with fibers other than glass. When a hull is being created in a female mould, the composite materials are applied to the mould in the form of a thermosetting plastic (usually epoxy, polyester, or vinylester) and some kind of fiber cloth (fiberglass, kevlar, dynel, carbon fiber, etc.). These methods can give strength-to-weight ratios approaching that of aluminum, while requiring less specialized tools and construction skills.
First developed in the mid-19th century in both France and Holland, ferrocement was also used for the D-Day Mulberry harbours. After a buzz of excitement among homebuilders in the 1960s, ferro building has since declined.
Ferrocement is a relatively cheap method to produce a hull, although unsuitable for commercial mass production. A steel and iron "armature" is built to the exact shape of the hull, ultimately being covered in galvanised chicken netting. Then, on a single day, the cement is applied by a team of plasterers. The cement:sand ratio is a very rich 4:1. As the hull thickness is typically 2.5 to 3 cms, ferrocement is unsuitable for boats less than about 15 metres LOA as there is a weight penalty; above that length there is no penalty. Properly plastered ferrocement boats have smooth hulls with fine lines, and amateur builders are advised to use professional plasterers to produce a smooth finish. In the 1960s and 1970s, particularly in Australia and New Zealand, the cheapness of ferro construction encouraged amateur builders to build hulls larger than they could afford, not anticipating that the fitting-out costs of a larger boat can be crippling.
The advantages of a ferro hull are:
The disadvantages are:
See also: concrete ship, concrete canoe.
There are many hull types, and a builder should choose the most appropriate one for the boat's intended purpose. For example, a sea-going vessel needs a hull which is more stable and robust than a hull used in rivers and canals. Hull types include:
A hull is the watertight body of a ship, boat, or flying boat. The hull may open at the top, or it may be fully or partially covered with a deck. Atop the deck may be a deckhouse and other superstructures, such as a funnel, derrick, or mast. The line where the hull meets the water surface is called the waterline.
The koch was a special type of small one or two mast wooden sailing ships designed and used in Russia for transpolar voyages in ice conditions of the Arctic seas, popular among the Pomors.
Carvel built or carvel planking is a method of boat building in which hull planks are laid edge to edge and fastened to a robust frame, thereby forming a smooth surface. Traditionally the planks are neither attached to, nor slotted into, each other, having only a caulking sealant between the planks to keep water out. Modern carvel builders may attach the planks to each other with glues and fixings. It is a "frame first" method of hull construction, where the shape is determined by the framework onto which the planks are fixed. This is in contrast to "plank first" or "shell first" methods, where the outer skin of the hull is made and then reinforced by the insertion of timbers that are fitted to that shape. The most common modern "plank first" method is clinker construction; in the classical period "plank first" involved joining the edges of planks with mortise and tenon joints within the thickness of the timbers, superficially giving the smooth-hull appearance of carvel construction, but achieved by entirely different means.
Strip-built, or "strip-plank epoxy", is a method of boat building. Also known as cold molding, the strip-built method is commonly used for canoes and kayaks, but also suitable for larger boats. The process involves securing narrow, flexible strips of wood edge-to-edge around temporary formers. The temporary formers are usually created via a process called "lofting" whereby a set of tables is used to generate the shapes of the formers. The strips are glued edge-to-edge with epoxy. It is effectively a modern form of carvel which needs no caulking and which is both stiffer and more watertight. In a small boat, there will be just one layer of strip-planking, but larger vessels may have two or three layers which,, forms a light, strong, and torsionally stiff monococque.
This glossary of nautical terms is an alphabetical listing of terms and expressions connected with ships, shipping, seamanship and navigation on water. Some remain current, while many date from the 17th to 19th centuries. The word nautical derives from the Latin nauticus, from Greek nautikos, from nautēs: "sailor", from naus: "ship".
Clinker built is a method of boat building where the edges of hull planks overlap each other. Where necessary in larger craft, shorter planks can be joined end to end, creating a longer strake or hull plank. The technique originated in Scandinavia, and was successfully used by the Anglo-Saxons, Frisians, Scandinavians, typically in the vessels known as cogs employed by the Hanseatic League. Carvel construction, where plank edges are butted smoothly, seam to seam, supplanted clinker construction in large vessels as the demand for capacity surpassed the limits of clinker construction..
On a vessel's hull, a strake is a longitudinal course of planking or plating which runs from the boat's stempost to the sternpost or transom. The garboard strakes are the two immediately adjacent to the keel on each side.
Sharpies are a type of hard chined sailboat with a flat bottom, extremely shallow draft, centreboards and straight, flaring sides. They are believed to have originated in the New Haven, Connecticut region of Long Island Sound, United States. They were traditional fishing boats used for oystering, and later appeared in other areas. With centerboards and shallow balanced rudders they are well suited to sailing in shallow tidal waters.
Philip C. Bolger was a prolific American boat designer, who was born and lived in Gloucester, Massachusetts. He began work full-time as a draftsman for boat designers Lindsay Lord and then John Hacker in the early 1950s.
A chine in boat design is a sharp change in angle in the cross section of a hull. The chine typically arises from the use of sheet materials as the mode of construction.
The Bell Woodworking Seagull and Seamew are both small sloop-rigged marine ply sailing boats of the Trailer yacht type designed by Ian Proctor, who was also responsible for the design of many small sailing dinghies in seven different classes including the extremely popular Topper, and Wanderer.
Fairey Marine Ltd, latterly known as FBM Marine, was a boat building company based on the River Hamble, Southampton, England. The company was created in the late 1940s by Sir Charles Richard Fairey and Fairey Aviation's managing director, Mr. Chichester-Smith. Both were avid sailing enthusiasts along with Chichester-Smith's good friend and former Olympic yachtsman, Charles Currey.
A sailing yacht, is a leisure craft that uses sails as its primary means of propulsion. A yacht may be a sail or power vessel used for pleasure, cruising, or racing. There is no standard definition, so the term applies here to sailing vessels that have a cabin with amenities that accommodate overnight use. To be termed a "yacht", as opposed to a "boat", such a vessel is likely to be at least 33 feet (10 m) in length and have been judged to have good aesthetic qualities. Sailboats that do not accommodate overnight use or are smaller than 30 feet (9.1 m) are not universally called yachts. Sailing yachts in excess of 130 feet (40 m) are generally considered to be superyachts.
Shell plating is the outer-most structure on the hull of a steel or aluminum ship or boat.
The Baba 30 was the smallest craft in the range but very popular, with some 170 having been built. They were built as sturdy vessels suitable for making long offshore and ocean passages needing only a couple of people to crew the boat. Although capable of sleeping 5 people they are generally sailed by couples. Most of these boats can be found in NW America but are also spread all around the world's ports and anchorages.
The Humber keel was a type of single-masted, square-rigged sailing craft used for inshore and inland cargo transport around Hull and the Humber Estuary, in the United Kingdom, particularly through the late 19th and early 20th centuries.
Norda is a wooden sailing vessel that was commissioned in 1928, originally used as a research vessel in Poland. It served as research vessel, fishing vessel and is now a yacht.
The Bluejacket 23 is a 23-foot (7.0 m) Canadian trailerable, fibreglass monohull sailboat designed by Cuthbertson & Cassian as a day sailer and club racer and first built in 1967.
The Dark Harbor 17 1/2 is a 25 ft 10 in long class of sailboat designed by B.B.Crowninshield in 1908 as a daysailer and racer.
The Watkins 25, also known as the W25 and marketed as the Seawolf 25 from 1986, is an American trailerable sailboat that was designed by the Watkins Design Team and first built in 1983.