# Anchor windlass

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A windlass is a machine used on ships that is used to let-out and heave-up equipment such as a ship's anchor or a fishing trawl. On some ships, it may be located in a specific room called the windlass room.

## Contents

An anchor windlass is a machine that restrains and manipulates the anchor chain on a boat, allowing the anchor to be raised and lowered by means of chain cable. A notched wheel engages the links of the chain or the rope.

A trawl windlass is a similar machine that restrains or manipulates the trawl on a commercial fishing vessel. The trawl is a sort of big fishing net that is wound on the windlass. The fishermen either let-out the trawl or heave-up the trawl during fishing operations. A brake is provided for additional control. The windlass is usually powered by an electric or hydraulic motor operating via a gear train.

## Horizontal or vertical

Technically speaking, the term "windlass" refers only to horizontal winches. Vertical designs are correctly called capstans. Horizontal windlasses make use of an integral gearbox and motor assembly, all typically located above-deck, with a horizontal shaft through the unit and wheels for chain and/or rope on either side. Vertical capstans use a vertical shaft, with the motor and gearbox situated below the winch unit (usually below decks).

Horizontal windlasses offer several advantages. The unit tends to be more self-contained, protecting the machinery from the corrosive environment found on boats. The dual wheels also allow two anchors on double rollers to be serviced. Vertical capstans, for their part, allow the machinery to be placed below decks, thus lowering the center of gravity (important on boats), and also allow a flexible angle of pull (which means rope or chain can be run out to different fair leads).

It tends to be the case that smaller boats use capstans, and larger boats have windlasses, although this is by no means a hard and fast rule.[ citation needed ]

The anchor is shackled to the anchor cable (US anchor chain), the cable passes up through the hawsepipe, through the pawl, over the windlass gypsy (US wildcat) down through the "spurling pipe" to the chain/cable locker under the forecastle (or poop if at the stern (US fantail)) - the anchor bitts are on a bulkhead in the cable locker and the bitter end of the cable is connected to the bitts using the bitter pin, which should be able to be released from outside the locker to "slip" the anchor. This would occur if the windlass brake has slipped (in a storm, for example) and the cable has reached "the bitter end". This is the origin of the term "to the bitter end". [1] It originally applied in sailing vessels where the cable was a rope, and the windlass or capstan was powered by many sailors below decks.

## Gypsies and wildcats

The wheels on either a vertical or horizontal windlass provide for either chain or line to be engaged. The wheel for line is termed a warping head, while the chain handling wheel is variously referred to as the gypsy (in the UK) or wildcat (in North America). For clarity in communication the generic term chainwheel is often used. On small craft a warping drum is sometimes used to handle both chain & rope, although particular care must be taken with sizing and compatibility of line, chain, and windlass, for this feature to work effectively.[ citation needed ]

It is important that the chainwheel match the chain size (i.e. the link pitch) closely. Even a small difference in link size or consistency can cause undue wear on the chainwheel and/or cause the chain to jump off the windlass when the winch is operating, particularly during payout, a runaway condition sometimes referred to as "water spouting" should it occur at high speed.[ citation needed ]

Nowadays, especially on large tankers and cruise ships, the windlass may be split into independent port and starboard units. In these cases they are frequently coupled with warping drums (as distinct from warping heads).[ clarification needed ] In some of these the warping drums are of the self tensioning or constant tension type.[ clarification needed ]

The mechanical advantage of a windlass is derived from the pulling force being multiplied by wrapping the rope around the drum.

The math for such force phenomena is described by the Capstan equation. The formula is

${\displaystyle T_{\text{load}}=T_{\text{hold}}\ e^{\mu \phi }~,}$

where ${\displaystyle T_{\text{load}}}$ is the applied tension on the line, ${\displaystyle T_{\text{hold}}}$ is the resulting force exerted at the other side of the capstan, ${\displaystyle \mu }$ is the coefficient of friction between the rope and capstan materials, and ${\displaystyle \phi }$ is the total angle swept by all turns of the rope, measured in radians (i.e., with one full turn the angle ${\displaystyle \phi =2\pi \,}$).

While many modern windlasses require an external power source, many remain manually driven in the same manner as most sailing boats' winches for sheets.

Powered solutions include steam (antiquated), hydraulics, and electrics. Electrics are convenient and relatively cheap, but hydraulics may be more efficient and powerful if available.

In general, windlasses and their power system should be capable of lifting the anchor and all its rode (chain and rope) so that the anchor and rode hang suspended in deep water. This task should be within the windlass' rated working pull, not its maximum pull.

## Devil's claw

The devil's claw is a device that is used as a chain stopper to grab and hold an anchor chain. It consists of a turnbuckle, usually attached at the base of the anchor windlass, and a metal hook with two curved fingers that grab one link of a chain.

A devil's claw is often used on merchant ships because it is lighter and easier to manage than other types of chain stoppers, such as a pelican hook.

After hoisting the anchor and setting the windlass brake, the claw is placed on a chain link and the turnbuckle is tightened to take up the tension on the chain. If more than one stopper is used, the turnbuckles can be adjusted to evenly distribute the load.

A devil's claw cannot be released while it is under tension. To release it, the tension must first be taken up by the windlass brake. Then the turnbuckle can be loosened and removed.

## Related Research Articles

An anchor is a device, normally made of metal, used to secure a vessel to the bed of a body of water to prevent the craft from drifting due to wind or current. The word derives from Latin ancora, which itself comes from the Greek ἄγκυρα (ankȳra).

In physics and geometry, a catenary is the curve that an idealized hanging chain or cable assumes under its own weight when supported only at its ends in a uniform gravitational field.

A suspension bridge is a type of bridge in which the deck is hung below suspension cables on vertical suspenders. The first modern examples of this type of bridge were built in the early 1800s. Simple suspension bridges, which lack vertical suspenders, have a long history in many mountainous parts of the world.

The windlass is an apparatus for moving heavy weights. Typically, a windlass consists of a horizontal cylinder (barrel), which is rotated by the turn of a crank or belt. A winch is affixed to one or both ends, and a cable or rope is wound around the winch, pulling a weight attached to the opposite end. The Greek scientist Archimedes was the inventor of the windlass. The oldest depiction of a windlass for raising water can be found in the Book of Agriculture published in 1313 by the Chinese official Wang Zhen of the Yuan Dynasty.

A winch is a mechanical device that is used to pull in or let out or otherwise adjust the tension of a rope or wire rope.

A mooring is any permanent structure to which a vessel may be secured. Examples include quays, wharfs, jetties, piers, anchor buoys, and mooring buoys. A ship is secured to a mooring to forestall free movement of the ship on the water. An anchor mooring fixes a vessel's position relative to a point on the bottom of a waterway without connecting the vessel to shore. As a verb, mooring refers to the act of attaching a vessel to a mooring.

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.

A fishing trawler is a commercial fishing vessel designed to operate fishing trawls. Trawling is a method of fishing that involves actively dragging or pulling a trawl through the water behind one or more trawlers. Trawls are fishing nets that are pulled along the bottom of the sea or in midwater at a specified depth. A trawler may also operate two or more trawl nets simultaneously.

This is a glossary of nautical terms; an alphabetical listing of terms and expressions connected with ships, shipping, seamanship and navigation on water, but not necessarily on the sea. 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.

A guy-wire, guy-line, guy-rope, or stay, also called simply a guy, is a tensioned cable designed to add stability to a free-standing structure. They are used commonly for ship masts, radio masts, wind turbines, utility poles, and tents. A thin vertical mast supported by guy wires is called a guyed mast. Structures that support antennas are frequently of a lattice construction and are called "towers". One end of the guy is attached to the structure, and the other is anchored to the ground at some distance from the mast or tower base. The tension in the diagonal guy-wire, combined with the compression and buckling strength of the structure, allows the structure to withstand lateral loads such as wind or the weight of cantilevered structures. They are installed radially, usually at equal angles about the structure, in trios and quads. As the tower leans a bit due to the wind force, the increased guy tension is resolved into a compression force in the tower or mast and a lateral force that resists the wind load. For example, antenna masts are often held up by three guy-wires at 120° angles. Structures with predictable lateral loads, such as electrical utility poles, may require only a single guy-wire to offset the lateral pull of the electrical wires, at a spot where the wires change direction.

Seine fishing is a method of fishing that employs a surrounding net, called a seine, that hangs vertically in the water with its bottom edge held down by weights and its top edge buoyed by floats. Seine nets can be deployed from the shore as a beach seine, or from a boat.

A capstan is a vertical-axled rotating machine developed for use on sailing ships to multiply the pulling force of seamen when hauling ropes, cables, and hawsers. The principle is similar to that of the windlass, which has a horizontal axle.

A fly system, or theatrical rigging system, is a system of rope lines, blocks (pulleys), counterweights and related devices within a theater that enables a stage crew to fly (hoist) quickly, quietly and safely components such as curtains, lights, scenery, stage effects and, sometimes, people. Systems are typically designed to fly components between clear view of the audience and out of view, into the large opening, known as the fly loft, above the stage.

A fishing vessel is a boat or ship used to catch fish in the sea, or on a lake or river. Many different kinds of vessels are used in commercial, artisanal and recreational fishing.

A Single buoy mooring (SrM) is a loading buoy anchored offshore, that serves as a mooring point and interconnect for tankers loading or offloading gas or liquid products. SPMs are the link between geostatic subsea manifold connections and weathervaning tankers. They are capable of handling any tonnage ship, even very large crude carriers (VLCC) where no alternative facility is available.

The capstan equation or belt friction equation, also known as Eytelwein's formula, relates the hold-force to the load-force if a flexible line is wound around a cylinder.

Wire rope spooling technology is the technology to prevent wire rope getting snagged when spooled, especially in multiple layers on a drum.

Rigging is both a noun, the equipment, and verb, the action of designing and installing the equipment, in the preparation to move objects. A team of riggers design and install the lifting or rolling equipment needed to raise, roll, slide or lift objects such as with a crane, hoist or block and tackle.

The following outline is provided as an overview of and topical guide to sailing:

This is a glossary of nautical terms; an alphabetical listing of terms and expressions connected with ships, shipping, seamanship and navigation on water, but not necessarily on the sea. 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.

## References

1. "Bitter end | Etymology, origin and meaning of phrase bitter end by etymonline".