In sailing, a boom is a spar (pole), along the foot (bottom) of a fore and aft rigged sail, that greatly improves control of the angle and shape of the sail. Sailing is the art of controlling a Sailing vessel. By changing the Rigging, Rudder and dagger or centre board a Sailor manages the force In Sailing, a spar is also know as a round pole of wood or Metal used on a Sailing ship. In Sailing the parts of a Sail have common terminology for each corner and edge of the sail A fore-and-aft rig is a Sailing rig consisting mainly of Sails that are set along the line of the Keel rather than perpendicular to it A sail is any type of surface intended to generate Thrust by being placed in a Wind &mdashin essence a vertically-oriented Wing. The primary action of the boom is to keep the foot of the sail flatter when the sail angle is away from the centerline of the boat. The boom also serves an attachment point for more sophisticated control lines. Because of the improved sail control it is rare to find a non headsail without a boom. A headsail of a Sailing vessel is any Sail set forward of the foremost mast. In some modern applications, the sail is rolled up into the boom for storage or reefing (shortening sail).
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Boom attachment
The forward end of the boom attaches to a mast just below the sail, with a joint called the gooseneck. The mast of a sailing ship is a tall vertical or near vertical Spar, or arrangement of Spars which supports the Sails Large ships have several masts The gooseneck is the Swivel connection on a Sailboat by which the boom attaches to the mast. The gooseneck pivots allowing the other end of the boom to move freely. The clew (back corner) of the sail attaches to the free end of the boom. In Sailing the parts of a Sail have common terminology for each corner and edge of the sail The entire foot of the sail may be attached to the boom or just the clew. In Sailing the parts of a Sail have common terminology for each corner and edge of the sail If the foot is not attached to the boom, the rig is known as loose footed.
A boom may be found on small headsails. A headsail of a Sailing vessel is any Sail set forward of the foremost mast. There the forward end of the boom is attached to the same stay as the sail's luff (forward edge). Stays are the heavy ropes wires or rods on Sailing vessels that run from the masts to the hull, usually fore-and-aft along the centerline of the vessel In Sailing the parts of a Sail have common terminology for each corner and edge of the sail
Lines on the boom
The control lines (ropes) on the boom act in conjunction with the halyard and leech line to ensure that the sail is trimmed most effectively. In Sailing, a halyard or halliard is a line ( Rope) that is used to hoist (pull up a Sail, a Flag or a yard.
Two primary sail control lines are attached to every boom:
- The outhaul runs from the clew of the sail to the free end of the boom. An outhaul is a line which is part of the Running rigging of a Sailboat, which is used to extend a Sail, and control the shape of the curve of the In Sailing the parts of a Sail have common terminology for each corner and edge of the sail Hauling in on (tightening) the outhaul increases foot tension in the main sail. Modern loose footed sails are cut so that the outhaul is also able to pull the clew downwards towards the boom.
- The sheet is attached midway along the boom or at the free end. In Sailing, a sheet is a line ( Rope, Cable or Chain) used to control the moveable corner(s of a Sail. In smaller boats such as dinghies it is used to control the angle of the sail to the wind on each point of sail. On larger boats this function is largely assumed by the traveller and the main sheet is used to adjust the twist of the sail to present the luff of the sail to the wind all of the way up the mast. In Sailing the parts of a Sail have common terminology for each corner and edge of the sail Easing the main sheet increases twist and the twist is usually adjusted so that the aft end of the top batten in the main sail runs parallel to the boom. A batten is a thin strip of solid material (usually Wood) Battens are used for various purposes in Building construction, as well as other various fields The traveller is a track running from one side of the boat to the other upon which sits a car to which the other end of the sheet is attached. A mechanical traveller is a moving part of a Machine, typically a ring that slides between different positions on a supporting rod when the machine goes through its operating Moving the car from side to side alters the angle of the boom to the centreline of the boat while minimising the effect on the twist of the sail.
A boom will frequently have these additional sail control lines attached:
- A downhaul may be attached to the boom near the gooseneck to pull the boom down and increase tension on the luff (forward edge) of the sail. The downhaul is a line which is part of the rigging on a Sailboat; it applies downward force on a Spar or Sail. In Sailing the parts of a Sail have common terminology for each corner and edge of the sail If no downhaul is present, the gooseneck is usually fixed vertically to the mast and a cunningham may be used to control luff tension. In Sailing, a cunningham or cunningham's eye is a type of Downhaul used on a Bermuda rigged sailboat to change the shape of a sail
- The boom vang, kicking strap or kicker is an intricate set of pulleys (and, on yachts, a hydraulic ram) running diagonally between the boom and the lower portion of the mast. A boom vang (US or kicking strap (UK is a line or piston system on a Sailboat used to exert downward force on the boom and thus control the shape The kicker pulls the boom downwards. When the boat is running away from the wind the sheet will be fully eased and so the kicker becomes the primary means of controlling sail twist.
- The Preventer, prevents the boom from jibing. A preventer, or jibe-guard, is a mechanical device on a sailing vessel which limits the boom 's ability to swing dangerously across the boat during an accidental This line is run from a point on the boom to a point forward such as a deck cleat or the base of a stanchion. Ideally, the preventer should run from the aft end of the boom to a turning block at or very close to the bow and then back to a cleat convenient to the cockpit. The line does not take tremendous force if used properly, but it prevents the boom from starting a jibe if the wind shifts or the boat rolls. Sophisticated form of preventer is a Boom Brake, which not only prevents unwanted jibes, but allows a slow measured jibe by modulating the tension on the brake. A boom brake is a device designed to control the swing of the boom on a Sailboat.
- Reef Lines, are used to tie-off excess sail, when sails are reefed (shortened). Some modern systems know as "jiffy reefing" or "slab reefing" have permanent lines running through the boom for purposes of reefing. Pulling on these lines helps to gather the excess sail at the bottom of the boom, and to secure the reef points to the fore and aft of the boom. With a well designed system sailors can reef the sails without leaving the cockpit.
Other lines that may found on a boom include:
- A topping lift, holds up the free end of the boom when the sail is lowered. The topping lift (more rarely known as an uphaul) is a line which is part of the rigging on a Sailboat; it applies upward force on a Spar
- Lazy jacks guide the sail onto the top of the boom for furling when the sail is lowered.
Boom material and hardware
Traditionally booms, and other spars, were made of wood. Classic wooden hulled sailboats, both old and new, will usually have wooden spars. When aluminum became available, it was adopted for sailboat spars. WikipediaNaming Aluminum spars are lighter and stronger than their wooden counterpart, require less maintenance and generally hold up better to marine conditions. Aluminum spars are usually associated with fiberglass boats, although you will still find a few early fiberglass hulled yachts that were equipped with wooden spars. On very large sailing vessels, the spars may be steel. Modern, high performance, racing yachts may have spars constructed of more expensive materials, such as carbon fiber.
Various hardware is found attached to the boom. The hardware could include fairleads, blocks, block tracks, and cleats. A fairlead is a device to guide a line rope or cable around an object or out of the way or to stop it from moving laterally For attachment, screws are used on wooden booms and screws or rivets on aluminum booms. A rivet is a mechanical Fastener. Before it is installed it consists of a smooth cylindrical shaft with a head on one end If the foot of the sail is attached to the boom, there may be hoops from the foot of the sail, around the boom, or there may be a track on the top for the boom into which fittings on the foot of the sail are slid.
In-Boom Furling
There are quite a few variations of in-boom furling available. Generally the boom is hollow with a spindle in the center upon which the sail is rolled (furled). The techniques for turning the spindle vary, but frequently a line is used to spin the spindle and recover or reef the sail. In most cases the sail can be full battened and has virtually infinite reefing options. Some sailors consider this approach safer than in-mast furling, since the sail can be lowered and flaked in the traditional method, in the case of mechanical failure. In most applications, the sail can be lowered or reefed from the cockpit. Most designs will not accommodate a loose-footed mainsail.
Other boom uses
On an open cockpit sailboat at a mooring, a tarpaulin may be run over the boom and tied to the rails to form a tent over the cockpit. In the Royal Navy, the term cockpit originally referred to the area where the Coxswain was stationed A tarpaulin or tarp is a large sheet of strong flexible Water resistant or Waterproof material often Cloth such as Canvas or polyester
In certain situations on larger boats, the boom can be used as a crane.
During certain sailing manoeuvres, the boom moves rapidly from one side of the boat to the other. A jibe or gybe is a sailing maneuver where a Sailing vessel turns its Stern through the wind such that the wind direction changes from one side of the Sailors must take care not to obstruct this movement with their head. Failure to do so can give one insight into the origins of the name boom.
See also
External links
The wishbone boom on Sailing craft is most commonly seen on Windsurfing boards (sailboards A yard is a Spar on a mast from which Sails are set It may be constructed of timber steel or from more modern materials like Aluminum orDapyx Software network: MP3 Explorer | Ebook Manager | Zenithic