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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 (such as sheet metal or marine ply) as the mode of construction.
Using sheet materials in boat construction is cheap and simple, but whereas these sheet materials are flexible longitudinally, they tend to be rigid vertically. Examples of steel vessels with hard chines include narrowboats and widebeams; examples of plywood vessels with hard chines include sailing dinghies such as the single-chined Graduate and the double-chined Enterprise. Although a hull made from sheet materials might be unattractively "slab-sided", most chined hulls are designed to be pleasing to the eye and hydrodynamically efficient.
Hulls without chines (such as clinker-built or carvel-built vessels) usually have a gradually curving cross section.
A hard chine is an angle with little rounding, where a soft chine would be more rounded, but still involve the meeting of distinct planes. Chine log construction is a method of building hard chine boat hulls. Hard chines are common in plywood hulls, while soft chines are often found on fiberglass hulls.
Traditional planked hulls in most cultures are built by placing wooden planks oriented parallel to the waterflow and attached to bent wooden frames. This also produced a rounded hull, generally with a sharp bottom edge to form the keel. Planked boats were built in this manner for most of history.[ citation needed ]
The first hulls to start incorporating hard chines were probably shallow draft cargo carrying vessels used on rivers and in canals. 
Once sufficiently powerful marine motors had been developed to allow powerboats to plane, it was found that the flat underside of a chined boat provided maximum hydrodynamic lift and speed. 
The scow in particular, in the form of the scow schooner, was the first significant example of a hard chine sailing vessel. While sailing scows had a poor safety reputation, that was due more to their typical cheap construction and tendency to founder in storms. As long as it sailed in the protected inland and coastal waters it was designed to operate in, however, the sailing scow was an efficient and cost effective solution to transporting goods from inland sources to the coast.[ citation needed ] A good example of this is the gundalow. 
Working in the same inland waters as the sailing scows was the later river steamboat. River steamboats were often built using the same hard chined construction methods of the sailing scows, with a flat bottom, hard chine, and nearly vertical sides. 
The punt is one of the simplest hard chine small boats. Consisting usually of a single plank for each side, with a square bow and stern, the punt was in essence a tiny scow.[ citation needed ]
The simplest type of chine construction is the single chine "V" shape, with two flat panels joined at the keel (A). This type of hull is among the simplest to build, but they lack stability on a narrow "V" and may lack freeboard on a wide "V". Single chine hulls are generally only seen on multihull sailboats, which often use two deep "V" shaped hulls connected by akas to provide mutual stability.
The two chine hull (B), with a flat bottom and nearly vertical sides, was the first hard chine design to achieve widespread use. This design provides far more stability than the single chine hull, with minimum draft and a large cargo capacity. These characteristics make the two chine hull popular for punts, barges, and scows.
The three chine hull (C) is probably the most common hard chine hull. Having a shallow "V" in the bottom and near-vertical panels above that, it approximates the shape of traditional rounded hull boats fairly well. This hull is common, even in fiberglass designs where employing chines offers no advantage in construction.
Designs with higher numbers of chines (D), often just called multichine hulls, are also common. By increasing the number of chines, the hull can very closely approximate a round bottomed hull. Kayaks, in particular, are often composed of many chines, required for the complex shapes needed to provide good performance under various conditions.
It is possible to refer to the different hulls by the numbers of the flat panels that make up the boat. Thus A is a two-panel boat, B is a three-panel boat, C is a four-panel boat and D is an eight-panel boat.
Plank hulls use wooden supports placed along the chines called chine logs to provide strength where the chines joined. Beams are then attached to the chine log to support planks running parallel to the chine, while cross-planked sections such as a typical scow bottom may be attached directly to the chine log. This method of construction originated with the sailing scow  and continues to be used today, primarily in home built boats.
Chine log construction works best for hulls where the sides join a flat bottom at a right angle, but it can be used for other angles as well with an appropriately angled chine log. Builders of small boats such as punts, where the plank thickness is large compared to the size of the hull, can dispense with the chine log and nail intersecting planks directly into one another.
A chined hull built out of plywood will often be designed to keep most of the lengthwise joints between the plywood sheets at the chines, thus making the building process easier. While chine logs (often just called chines) can be used for plywood boats,  another common technique replaces the chine logs with a fiberglass and epoxy fillet joint that provides both connection and stiffness to the joint; this method is most commonly called stitch and glue construction.
A padded v-hull is a hull shape found on both pure race boats and standard recreational craft. A variation of the more common v-hull, which has a v-section throughout the length of the vessel, a padded v-hull has a v-section at the bows and the forward part of the keel which then segues into a flat area typically 0.15 metres (5.9 in) to 0.25 metres (9.8 in) wide. This flat area at the rear is the "pad", and is said to provide hydrodynamic lift more efficiently due to very low deadrise planing surface (compared to the vee hull lifting surfaces). This highly efficient lift helps to unwet the less efficient vee sections hull, thereby dramatically reducing drag (force). As the boat's speed increases, hydrodynamic pressure beneath the pad causes the hull to ride higher in the water, so that eventually the boat will be riding solely upon the pad area.
At low speeds these hulls ride and handle similarly to a comparable v-hull; but at high speeds the padded hull can both out-accelerate and have a higher top speed than a similarly powered v-hull. Piloting a padded v-hull requires considerable skill, since at high speed the hull is riding upon a small pad. The driver must make slight, accurate steering inputs to maintain level progress, as otherwise padded v-hulls tend to "chine-walk".  As speeds increase, chine-walk becomes more pronounced and may lead to loss of control unless the driver is able to compensate for it. 
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.
A yacht is a sailing or power vessel used for pleasure, cruising, or racing. There is no standard definition, though the term generally applies to vessels with a cabin intended for overnight use. To be termed a yacht, as opposed to a boat, such a pleasure vessel is likely to be at least 33 feet (10 m) in length and may have been judged to have good aesthetic qualities.
The keel is the bottom-most longitudinal structural element on a vessel. On some sailboats, it may have a hydrodynamic and counterbalancing purpose, as well. The laying of the keel is often the initial step in the construction of a ship. In the British and American shipbuilding traditions, this event marks the beginning date of a ships construction.
A scow is a smaller type of barge. Some scows are rigged as sailing scows. In the 19th and early 20th centuries, scows carried cargo in coastal waters and inland waterways, having an advantage for navigating shallow water or small harbours. Scows were in common use in the American Great Lakes and other parts of the U.S., Canada, southern England, and New Zealand. In modern times their main purpose is for recreation and racing.
A sampan is a relatively flat-bottomed Chinese and Malay wooden boat. Some sampans include a small shelter on board and may be used as a permanent habitation on inland waters. The design closely resembles Western hard chine boats like the scow or punt. Sampans are generally used for transportation in coastal areas or rivers and are often used as traditional fishing boats. It is unusual for a sampan to sail far from land, as they do not have the means to survive rough weather.
A rigid inflatable boat (RIB), also rigid-hull inflatable boat or rigid-hulled inflatable boat (RHIB), is a lightweight but high-performance and high-capacity boat constructed with a rigid hull bottom joined to side-forming air tubes that are inflated with air to a high pressure so as to give the sides resilient rigidity along the boat's topsides. The design is stable, light, fast and seaworthy. The inflated collar acts as a life jacket, ensuring that the vessel retains its buoyancy, even if the boat is taking on water. The RIB is an evolutionary development of the inflatable boat with a rubberized fabric bottom that is stiffened with flat boards within the collar to form the deck or floor of the boat.
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.
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.
Planing is the mode of operation for a waterborne craft in which its weight is predominantly supported by hydrodynamic lift, rather than hydrostatic lift (buoyancy).
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".
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.
The Moth is a small development class of sailing dinghy. Originally a small, fast home-built sailing boat designed to plane, since 2000 it has become an expensive and largely commercially-produced boat designed to hydroplane on foils though many are still built at home, typically at much lower cost.
The Y Flyer is an American sailing dinghy that was designed by Alvin Youngquist in 1938 as a one-design racer and first built in 1941.
The Chesapeake Bay deadrise or deadrise workboat is a type of traditional fishing boat used in the Chesapeake Bay. Watermen use these boats year round for everything from crabbing and oystering to catching fish or eels.
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.
The Norfolk Punt is a type of yacht, derived from the flat-bottomed gun punts that roamed the Broadland waters in the mid-to-late 19th century. However, at the turn of the 20th century, in order to get to and from the hunting grounds more quickly, the punters developed their highly unstable craft to carry a basic mast and sail for travelling with the wind. It is from these humble beginnings that one of the country's most exciting and powerful racing dinghy classes was born.
A flat-bottomed boat is a boat with a shallow draft, two-chined hull, which allows it to be used in shallow bodies of water, such as rivers, because it is less likely to ground.
The Lürssen effect, used in the design of high-speed boats, is a reduction in wave-making resistance provided by two small rudders mounted on each side of the main rudder and turned outboard. These rudders force the water under the hull outward, lifting the stern, thus reducing drag, and lowering the wake height, which “requires less energy, allowing the vessel to go faster.” The effect was discovered by the German shipbuilding company Lürssen Werft based in Bremen-Vegesack. The Lürssen effect is best remembered for its use during the Second World War in the various classes of German "Schnellboot," or fast torpedo attack boats.
The Ranger 24 is an American trailerable sailboat that was designed by Raymond H. Richards as an International Offshore Rule Quarter Ton class racer-cruiser and first built in 1974.