Chine (boating)
Encyclopedia
A chine in boating refers to a sharp angle in the hull
, as compared to the rounded bottoms of most traditional boat hulls. The term hard chine indicates 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.
canoes, which were built by hollowing out a log. These designs generally had rounded bottoms, which made best use of the round shape of the logs. 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.
The first hulls to start incorporating hard chines were probably shallow draft cargo carrying vessels used on rivers and in canal
s. The barge
and later the scow
used a flat bottom and near vertical sides, which provided the maximum cargo carrying capacity (in both space and displacement
) available for a given depth of water.
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, while the sharp discontinuity at the chine enabled spray to be deflected away as opposed to riding up the sides of the boat. Consequently, almost all boats designed for high speed on the plane are nowadays of hard chine construction.
, was the first significant example of a hard chine sailing vessel. While the squared off scow hulls were ugly to sailors accustomed to the sleek, rounded hulls of the time, a scow could carry far more cargo, and while a laden scow was slow and difficult to sail, when not heavily laden it would keep up with the traditional schooners sailing to windward. 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. A good example of this is the gundalow.
is one of the older and 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. The sides of a punt are vertical, and they were typically propelled along shallow waters with a long pole, a method of propulsion referred to as punting. Punts are generally used for recreation, and are popular with duck
hunters for their ability to move in marsh
y hunting areas.
The simplest type of chine construction would be 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 due to the lack of stability of a narrow "V" and the lack of 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
, barge
s, and the scow
s.
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, and 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. Kayak
s, in particular, are often composed of many chines, required for the complex shapes needed to provide good performance under various conditions. By increasing the number of chines, the hull can very closely approximate a round bottomed hull.
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 a eight panel boat.
Construction of a chined hull is subject to many different parameters than a round hull, both positive and negative:
in nature, with the hull planking itself bearing most of the structural load.
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.
and epoxy
fillet
joint that provides both connection and stiffness to the joint; this method is most commonly called stitch and glue
construction. The result of the stitch and glue operation is a composite
"chine log", with a much greater degree of flexibility in curvature and shape than is possible with a wooden chine log.
Commercial fiberglass hulls are molded, and since the fiberglass and resin
used have no inherent shapes, the mold can be of just about any shape. However, molds for low production boats are often made of plywood, and so the properties of the plywood often result in a chined hull. Hard chines may be rounded off by the addition of filler to the mold to create a fillet; this creates the soft chines often found on fiberglass boats.
Hull (watercraft)
A hull is the watertight body of a ship or boat. Above the hull is the superstructure and/or deckhouse, where present. The line where the hull meets the water surface is called the waterline.The structure of the hull varies depending on the vessel type...
, as compared to the rounded bottoms of most traditional boat hulls. The term hard chine indicates 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
Plywood
Plywood is a type of manufactured timber made from thin sheets of wood veneer. It is one of the most widely used wood products. It is flexible, inexpensive, workable, re-usable, and can usually be locally manufactured...
hulls, while soft chines are often found on fiberglass
Fiberglass
Glass fiber is a material consisting of numerous extremely fine fibers of glass.Glassmakers throughout history have experimented with glass fibers, but mass manufacture of glass fiber was only made possible with the invention of finer machine tooling...
hulls.
Reasons for chines
The oldest type of engineered boats are dugoutDugout (boat)
A dugout or dugout canoe is a boat made from a hollowed tree trunk. Other names for this type of boat are logboat and monoxylon. Monoxylon is Greek -- mono- + ξύλον xylon -- and is mostly used in classic Greek texts. In Germany they are called einbaum )...
canoes, which were built by hollowing out a log. These designs generally had rounded bottoms, which made best use of the round shape of the logs. 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
Keel
In boats and ships, keel can refer to either of two parts: a structural element, or a hydrodynamic element. These parts overlap. As the laying down of the keel is the initial step in construction of a ship, in British and American shipbuilding traditions the construction is dated from this event...
. Planked boats were built in this manner for most of history.
The first hulls to start incorporating hard chines were probably shallow draft cargo carrying vessels used on rivers and in canal
Canal
Canals are man-made channels for water. There are two types of canal:#Waterways: navigable transportation canals used for carrying ships and boats shipping goods and conveying people, further subdivided into two kinds:...
s. The barge
Barge
A barge is a flat-bottomed boat, built mainly for river and canal transport of heavy goods. Some barges are not self-propelled and need to be towed by tugboats or pushed by towboats...
and later the scow
Scow
A scow, in the original sense, is a flat-bottomed boat with a blunt bow, often used to haul bulk freight; cf. barge. The etymology of the word is from the Dutch schouwe, meaning such a boat.-Sailing scows:...
used a flat bottom and near vertical sides, which provided the maximum cargo carrying capacity (in both space and displacement
Displacement (fluid)
In fluid mechanics, displacement occurs when an object is immersed in a fluid, pushing it out of the way and taking its place. The volume of the fluid displaced can then be measured, as in the illustration, and from this the volume of the immersed object can be deduced .An object that sinks...
) available for a given depth of water.
Once sufficiently powerful marine motors had been developed to allow powerboats to plane
Planing (sailing)
Planing is the mode of operation for a waterborne craft in which its weight is predominantly supported by hydrodynamic lift, rather than hydrostatic lift .-History:...
, it was found that the flat underside of a chined boat provided maximum hydrodynamic lift, while the sharp discontinuity at the chine enabled spray to be deflected away as opposed to riding up the sides of the boat. Consequently, almost all boats designed for high speed on the plane are nowadays of hard chine construction.
Sailing scows
The scow in particular, in the form of the scow schoonerSchooner
A schooner is a type of sailing vessel characterized by the use of fore-and-aft sails on two or more masts with the forward mast being no taller than the rear masts....
, was the first significant example of a hard chine sailing vessel. While the squared off scow hulls were ugly to sailors accustomed to the sleek, rounded hulls of the time, a scow could carry far more cargo, and while a laden scow was slow and difficult to sail, when not heavily laden it would keep up with the traditional schooners sailing to windward. 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. A good example of this is the gundalow.
Steamboats
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.Small boats
The puntPunt (boat)
A punt is a flat-bottomed boat with a square-cut bow, designed for use in small rivers or other shallow water. Punting refers to boating in a punt. The punter generally propels the punt by pushing against the river bed with a pole...
is one of the older and 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. The sides of a punt are vertical, and they were typically propelled along shallow waters with a long pole, a method of propulsion referred to as punting. Punts are generally used for recreation, and are popular with duck
Duck
Duck is the common name for a large number of species in the Anatidae family of birds, which also includes swans and geese. The ducks are divided among several subfamilies in the Anatidae family; they do not represent a monophyletic group but a form taxon, since swans and geese are not considered...
hunters for their ability to move in marsh
Marsh
In geography, a marsh, or morass, is a type of wetland that is subject to frequent or continuous flood. Typically the water is shallow and features grasses, rushes, reeds, typhas, sedges, other herbaceous plants, and moss....
y hunting areas.
Various types of chine hulls
Multihull
A multihull is a ship, vessel, craft or boat with more than one hull.-Description:Multihulls include: Proas, which have two differently shaped or sized hulls with lateral symmetry; catamarans, which have two hulls with longitudinal symmetry; and trimarans, which have a main hull in the center and...
sailboats, which often use two deep "V" shaped hulls connected by akas
Aka (sailing)
The aka of a multihull sailboat is a member of the framework that connects the hull to the ama . The term aka originated with the proa, but is also applied to modern trimarans....
to provide mutual stability.
The two chine hull (B), with a flat bottom
Flat-bottomed boat
A flat-bottomed boat is a boat with a flat bottomed, two-chined hull, which allows it be used in shallow bodies of water, such as rivers, because it is less likely to ground....
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
Punt (boat)
A punt is a flat-bottomed boat with a square-cut bow, designed for use in small rivers or other shallow water. Punting refers to boating in a punt. The punter generally propels the punt by pushing against the river bed with a pole...
, barge
Barge
A barge is a flat-bottomed boat, built mainly for river and canal transport of heavy goods. Some barges are not self-propelled and need to be towed by tugboats or pushed by towboats...
s, and the scow
Scow
A scow, in the original sense, is a flat-bottomed boat with a blunt bow, often used to haul bulk freight; cf. barge. The etymology of the word is from the Dutch schouwe, meaning such a boat.-Sailing scows:...
s.
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, and 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. Kayak
Kayak
A kayak is a small, relatively narrow, human-powered boat primarily designed to be manually propelled by means of a double blade paddle.The traditional kayak has a covered deck and one or more cockpits, each seating one paddler...
s, in particular, are often composed of many chines, required for the complex shapes needed to provide good performance under various conditions. By increasing the number of chines, the hull can very closely approximate a round bottomed hull.
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 a eight panel boat.
Constructing a chined hull
- The sharp angles do not favor bent wooden frames
- The wide, flat panels may be cross-planked, where the planks may run perpendicular to the keel rather than parallel to it
- Planks may be of any width, not just a width small enough to approximate the curve of the hull, and most planks can be cut with square edges
- Flat sections do not provide the stiffness of a rounded section
Plank hulls
The limitations of wood plank construction, the desire to maximize cargo volume, and the quest for fast, easy hull building led to a new type of construction method unique to chined hulls. This new method used 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. Use of a chine log provides some structural support, but most chine log hulls are primarily monocoqueMonocoque
Monocoque is a construction technique that supports structural load by using an object's external skin, as opposed to using an internal frame or truss that is then covered with a non-load-bearing skin or coachwork...
in nature, with the hull planking itself bearing most of the structural load.
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.
Plywood hulls
Plywood offers the builder a better "plank", far wider, thinner, and stronger than a simple wood plank. A chined hull built out of plywood will often be designed to keep most of the joints between the plywood sheets at the chines, thus making the building process easier. While chine logs can be and still are used for plywood boats, a more common technique replaces the chine logs with a fiberglassFiberglass
Glass fiber is a material consisting of numerous extremely fine fibers of glass.Glassmakers throughout history have experimented with glass fibers, but mass manufacture of glass fiber was only made possible with the invention of finer machine tooling...
and epoxy
Epoxy
Epoxy, also known as polyepoxide, is a thermosetting polymer formed from reaction of an epoxide "resin" with polyamine "hardener". Epoxy has a wide range of applications, including fiber-reinforced plastic materials and general purpose adhesives....
fillet
Fillet (mechanics)
In mechanical engineering, a fillet is a concave easing of an interior corner of a part design. A rounding of an exterior corner is called a "round" or a "chamfer".-Applications:...
joint that provides both connection and stiffness to the joint; this method is most commonly called stitch and glue
Stitch and glue
Stitch and glue is a simple boat building method which uses plywood, epoxy glue, and "stitches" and eliminates the need for stems and chines. Plywood panels are cut to detailed profiles and stitched together to form an accurate hull shape, without the need for forms or special tools...
construction. The result of the stitch and glue operation is a composite
Composite material
Composite materials, often shortened to composites or called composition materials, are engineered or naturally occurring materials made from two or more constituent materials with significantly different physical or chemical properties which remain separate and distinct at the macroscopic or...
"chine log", with a much greater degree of flexibility in curvature and shape than is possible with a wooden chine log.
Fiberglass hulls
Many home-built fiberglass hulls are built just like plywood hulls; sheets of a core material, often plywood or a synthetic foam, are joined together to form the shape of the hull, and the fiberglass is applied to this core to form the hull. In this case the hull shape is determined by the core materials, so core materials that favor hard chine design will usually result in a hard chine final product.Commercial fiberglass hulls are molded, and since the fiberglass and resin
Resin
Resin in the most specific use of the term is a hydrocarbon secretion of many plants, particularly coniferous trees. Resins are valued for their chemical properties and associated uses, such as the production of varnishes, adhesives, and food glazing agents; as an important source of raw materials...
used have no inherent shapes, the mold can be of just about any shape. However, molds for low production boats are often made of plywood, and so the properties of the plywood often result in a chined hull. Hard chines may be rounded off by the addition of filler to the mold to create a fillet; this creates the soft chines often found on fiberglass boats.