Chine (boating)
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A chine in boat design is a sharp change in angle in the
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of a hull. The chine typically arises from the use of sheet materials (such as
sheet metal Sheet metal is metal formed into thin, flat pieces, usually by an industrial process. Sheet metal is one of the fundamental forms used in metalworking, and it can be cut and bent into a variety of shapes. Thicknesses can vary significantly; ex ...
or marine ply) as the mode of construction.


Rationale of chines

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
narrowboat A narrowboat is a particular type of canal boat, built to fit the narrow locks of the United Kingdom. The UK's canal system provided a nationwide transport network during the Industrial Revolution, but with the advent of the railways, commerc ...
s and
widebeam A widebeam is a canal boat built in the style of a British narrowboat but with a beam of or greater.The Canal and River Trust (CRT) gives more than one minimum width for a wide beam on their website: "anything wider than []" in ''Wide beam, wide ...
s; examples of plywood vessels with hard chines include sailing dinghies such as the single-chined Graduate (dinghy), Graduate and the double-chined Enterprise (dinghy), 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 hydrodynamics, hydrodynamically efficient. Hulls without chines (such as
clinker-built Clinker built (also known as lapstrake) is a method of boat building where the edges of hull (watercraft), hull planks overlap each other. Where necessary in larger craft, shorter planks can be joined end to end, creating a longer strake or hull ...
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 Plywood is a material manufactured from thin layers or "plies" of wood veneer that are glued together with adjacent layers having their wood grain rotated up to 90 degrees to one another. It is an engineered wood from the family of manufactured ...
hulls, while soft chines are often found on
fiberglass Fiberglass (American English) or fibreglass (Commonwealth English) is a common type of fiber-reinforced plastic using glass fiber. The fibers may be randomly arranged, flattened into a sheet called a chopped strand mat, or woven into glass cloth ...
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 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. As the laying down of the keel is the initial step in the construction of a ship, in Br ...
. 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 Canals or artificial waterways are waterways or engineered channels built for drainage management (e.g. flood control and irrigation) or for conveyancing water transport vehicles (e.g. water taxi). They carry free, calm surface flow un ...
s. Once sufficiently powerful marine motors had been developed to allow powerboats to
plane Plane(s) most often refers to: * Aero- or airplane, a powered, fixed-wing aircraft * Plane (geometry), a flat, 2-dimensional surface Plane or planes may also refer to: Biology * Plane (tree) or ''Platanus'', wetland native plant * ''Planes' ...
, it was found that the flat underside of a chined boat provided maximum hydrodynamic lift and speed.


Boats using chines

The
scow 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. S ...
in particular, in the form of the scow
schooner A schooner () is a type of sailing vessel defined by its rig: fore-and-aft rigged on all of two or more masts and, in the case of a two-masted schooner, the foremast generally being shorter than the mainmast. A common variant, the topsail schoon ...
, 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
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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 A gundalow (also known in period accounts as a "gondola") is a type of flat-bottomed sailing barge once common in Maine and New Hampshire rivers. It first appeared in the mid-1600s, reached maturity of design in the 1700 and 1800s, and lingered i ...
. Working in the same inland waters as the sailing scows was the later
river steamboat A steamboat is a boat that is propelled primarily by steam power, typically driving propellers or paddlewheels. Steamboats sometimes use the prefix designation SS, S.S. or S/S (for 'Screw Steamer') or PS (for 'Paddle Steamer'); however, thes ...
. 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.


Various types of chine hulls

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 A multihull is a boat or ship with more than one hull, whereas a vessel with a single hull is a monohull. The most common multihulls are catamarans (with two hulls), and trimarans (with three hulls). There are other types, with four or more h ...
sailboats, which often use two deep "V" shaped hulls connected by
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* Acas (disambiguation) * Ackas, a town in Finland * Akash (disambiguation) * Aka (disambigua ...
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 Barge nowadays generally refers to a flat-bottomed inland waterway vessel which does not have its own means of mechanical propulsion. The first modern barges were pulled by tugs, but nowadays most are pushed by pusher boats, or other vessels ...
s, and
scow 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. S ...
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. 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.
Kayak A kayak is a small, narrow watercraft which is typically propelled by means of a double-bladed paddle. The word kayak originates from the Greenlandic word ''qajaq'' (). The traditional kayak has a covered deck and one or more cockpits, each se ...
s, 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

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.


Plywood hulls

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 Fiberglass (American English) or fibreglass (Commonwealth English) is a common type of fiber-reinforced plastic using glass fiber. The fibers may be randomly arranged, flattened into a sheet called a chopped strand mat, or woven into glass cloth ...
and
epoxy Epoxy is the family of basic components or cured end products of epoxy resins. Epoxy resins, also known as polyepoxides, are a class of reactive prepolymers and polymers which contain epoxide groups. The epoxide functional group is also coll ...
fillet Fillet may refer to: *Annulet (architecture), part of a column capital, also called a fillet *Fillet (aircraft), a fairing smoothing the airflow at a joint between two components *Fillet (clothing), a headband *Fillet (cut), a piece of meat *Fille ...
joint that provides both connection and stiffness to the joint; this method is most commonly called
stitch and glue Stitch and glue is a simple boat building method which uses plywood panels temporarily stitched together, typically with wire or zip-ties, and glued together permanently with epoxy resin. This type of construction can eliminate much of the need f ...
construction.


Padded v-hulls

A padded v-hull is a hull shape found on both pure race boats and standard recreational
craft A craft or trade is a pastime or an occupation that requires particular skills and knowledge of skilled work. In a historical sense, particularly the Middle Ages and earlier, the term is usually applied to people occupied in small scale prod ...
. A variation of the more common
v-hull The V-hull is a type of vehicle armor design used on wheeled armored personnel carriers (APCs), infantry mobility vehicles, infantry fighting vehicles (IFVs) and MRAPs. The design originated in the 1970s with vehicles such as the iconic Casspir ...
, 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 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. As the laying down of the keel is the initial step in the construction of a ship, in Br ...
which then segues into a flat area typically to 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) In fluid dynamics, drag (sometimes called air resistance, a type of friction, or fluid resistance, another type of friction or fluid friction) is a force acting opposite to the relative motion of any object moving with respect to a surrounding flu ...
. 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 t
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.


See also

*
Strake On a vessel's hull, a strake is a longitudinal course of planking or plating which runs from the boat's stempost (at the bows) to the sternpost or transom (at the rear). The garboard strakes are the two immediately adjacent to the keel on ...
* Smooth curve hull


References

{{reflist


External links


Hull Technology in Hydrostream Boats




Nautical terminology Shipbuilding Naval architecture Engineering concepts