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29-414: During an unplanned accidental jibe (or gybe ), neither the crew nor the boat is set up properly to execute a planned jibe. As a result, the uncontrolled boom will swing across the boat potentially inflicting injury or knocking crew members overboard. The mainsheet or traveller can also inflict serious injury. Uncontrolled jibes may also damage the boat itself. Rigging a preventer on a yacht's mainsail

58-431: A dinghy . When the foot of a sail is attached along its whole length to a boom, the stiffness of the boom tends to hold the lower part of the sail flat. However, the greatest aerodynamic efficiency of the sail is created when the sail is allowed to curve into an airfoil -like shape. A flexible boom bends with the sail to create this greater efficiency. A "Park Avenue" boom allows for the same aerodynamic curvature as

87-429: 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

116-410: A flexible boom, but is a rigid construction with a flat surface on top. Instead of being fastened directly to the boom, the foot of the sail is fastened to fittings that slot into grooves that run transversely across the boom. As these fittings move within their grooves, the foot of the sail is free to curve. It takes its name from the great width of such a boom fitted to the yacht Enterprise for

145-413: Is a possibility of breaking the main boom with a preventer rig such as this, but many modern yachts are considered to have short enough booms and be beamy enough to overlook this possibility in normal use. For example, while running with the preventer cleated, a large swell could roll the boat, dipping the boom end into the water, snapping the boom in half. Care should be taken when selecting the rope which

174-432: Is found attached to the boom. The hardware could include fairleads , blocks , block tracks, and cleats . For attachment, screws are used on wooden booms and screws or rivets on aluminium booms. 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 of the boom into which fittings on the foot of the sail are slid. There are quite

203-413: Is often performed when the wind is behind the beam (i.e. when it's coming from more than 90° off the bow). It can also be useful at other times when there is more swell than wind , a situation when the wind may not have the strength to keep the boom in place as the boat dips and rolls. On any boat that is sailing downwind without a preventer, strict 'heads-down' procedures must be enforced anywhere within

232-402: Is used for preventer lines. To reduce the shock loads on the tackles, for example in an unexpected jibe, three-strand nylon line may be preferred over braided cored line. Another form of preventer is the boom brake , which, when sailing downwind, can also be used to jibe the mainsail in a slow, measured action. The brake usually rides on a line running perpendicular to, and below the boom. When

261-453: The 1930 America's Cup competition, a hyperbolic comparison to the width of Park Avenue . Fore and aft A fore-and-aft rig is a sailing vessel rig with sails set mainly along the line of the keel , rather than perpendicular to it as on a square rigged vessel. Fore-and-aft rigged sails include staysails , Bermuda rigged sails, gaff rigged sails, gaff sails , gunter rig, lateen sails, lug sails , tanja sails ,

290-553: The crab claw sail . It is suggested that it evolved from a more primitive V-shaped "square" sail with two spars that come together at the hull. Crab claw sails spread from Maritime Southeast Asia to Micronesia , Island Melanesia , Polynesia , and Madagascar via the Austronesian migrations. Austronesians in Southeast Asia also later developed other types of fore-and-aft sails, such as the tanja sail (also known as

319-453: The halyard and leech line to ensure that the sail is trimmed most effectively. Two primary sail control lines are attached to every boom: A boom will frequently have these additional sail control lines attached: Other lines that may be found on a boom include: Traditionally booms, and other spars, were made of wood. Classic wooden hulled sailboats, both old and new, will usually have wooden spars. When aluminium became available, it

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348-426: The mainsheet . Many cruising sailors prefer to rig two tackles (port and starboard) that run from the midpoint of the boom to blocks on a track such as the headsail-sheet-block track. These tackles are typically a 2 - 4 part tackles for greater purchase. This rig can also be used as a boom vang without taking up space under the mast that may be essential to the cruising sailor for dinghy stowage and other uses. There

377-475: The spanker sail on a square rig and crab claw sails . Fore-and-aft rigs include: Barques and barquentines are partially square rigged and partially fore-and-aft rigged. A rig which combines both on a foremast is known as a hermaphroditic rig. The fore-and-aft rig is believed to have been first developed independently by the Austronesian peoples some time around 1500 BC with the invention of

406-543: The US Coast Guard and Air National Guard utilized a Lockheed C-130 Hercules aircraft to rescue a man from 1400 miles off the Mexican coast. Deaths and injuries can occur on boats operating upon lakes and coastal waters. As a precaution, any sailboat with a low boom should mandate use of life jackets , and ensure others know how to obtain assistance and operate the craft. In Boston a sailor knocked overboard by

435-425: The boom brake is actuated, friction on the line either works as a preventer (stops the boom from moving in the direction that would slacken the main sheet), or slows the boom's speed while jibing. The brake is actuated by either tensioning the line upon which it rides or by using a second line to adjust the brake itself. When jibing a fully loaded mainsail in a following sea, the following procedure may be used. Using

464-435: The boom completely. Classic types of sail like the square rig or the standing lugsail have always worked without booms. Modern alternatives without a boom are the mast aft rig . 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 certain situations on larger boats, the boom can be used as a crane to help lift aboard heavy items like

493-405: The boom died in full sight of the land and other boats and the person left aboard didn't know how to use the radio. To address the dangers associated with the boom, some designers have raised the boom higher off the deck or applied padding. However, these raise the center of gravity and increase the chances of capsizing and turtling . Some designers have addressed the issue by eliminating

522-444: The boom may swing, and a call of "Jibe-ho" is a traditional last warning for this. At this point, a slight steering adjustment will actually jibe the sail. The course of the boat may slew further than expected, which can be ignored as it gives a shorthanded crew time to do the next three things: Run out the mainsheet as fast as possible without burning the hands, ensuring that the newly-lazy preventer runs free, then tighten in and secure

551-441: The boom to perform sail maintenance and install or take off sail covers. Falls from the boom onto the deck below occur. Even when stationary, booms represent a hazard since on most boats there is insufficient headroom to walk below them without ducking. According to a German study, "boom strikes were the most common cause of sailing injury overall". When boom injuries occur far from shore they can require expensive rescues. In 2010

580-427: The boom's arc. Certain areas of the side-decks and maybe the cockpit also have to be strictly 'no-go' to all crew depending on what the boom and mainsheet could do in unchecked full swing. The preventer with the most mechanical advantage is a line, from the end of the boom, led outside the shrouds and a long way forward - perhaps right up to the bow - through a block , back to the cockpit and secured within reach of

609-642: The canted square sail, canted rectangular sail, or the balance lug sail). Their use later spread into the Indian Ocean since the first millennium, among vessels from the Middle East , South Asia , and China . The lateen was developed in the Mediterranean as early as the 2nd century AD, during Roman times. It became common by the 5th century. The square rig had predominated in Europe since

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638-660: The dawn of sea travel, but in the generally gentle climate of southern Europe and the Mediterranean Sea during the last few centuries before the Renaissance the fore-and-aft began to replace it. By 1475, its use increased, and within a hundred years the fore-and-aft rig was in common use on rivers and in estuaries in Britain, northern France, and the Low Countries, though the square rig remained standard for

667-449: The improved sail control it is rare to find a non- headsail without a boom, but lateen sails , for instance, are loose-footed. In some modern applications, the sail is rolled up into the boom for storage or reefing (shortening sail). The forward end of the boom attaches to a mast just below the sail, with a joint called the gooseneck . The gooseneck pivots allowing the other end of the boom to move freely. The clew (back corner) of

696-434: The newly working preventer. Boom (sailing) In sailing , a boom is a spar (pole), along the foot of a fore and aft rigged sail , that greatly improves control of the angle and shape of the sail. The primary action of the boom is to keep the foot flatter when the sail angle is away from the centerline of the boat. The boom also serves as an attachment point for more sophisticated control lines. Because of

725-414: The sail attaches to the free end of the boom. The entire foot of the sail may be attached to the boom or just the clew. If the foot is not attached to the boom, the rig is known as loose footed . A boom may be found on small headsails . There the forward end of the boom is attached to the same stay as the sail's luff (forward edge). The control lines (ropes) on the boom act in conjunction with

754-497: 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 . The second leading cause of death on sailboats is directly attributed to the use of booms. Booms can cause injuries directly, sweep people overboard, and their associated hardware and lines represent tripping hazards. On larger boats, sailors tend to stand on

783-463: The steering, the stern of the boat is carefully brought up into the wind. Then the leeward , working preventer is released little by little, while the mainsheet is shortened to bring in the boom. It is important to maintain at least a turn or two around the preventer's cleat the whole time ready to catch an early jibe during this stage of the manoeuvre. The mainsheet should pull the preventer around its cleat, without it being offered any slack. All

812-422: The while it is also necessary to take in slack on the lazy preventer to keep it under control (i.e. prevent it getting tangled around something) until it is needed. When the boom is as near as possible to midships (near to running fore-and-aft along the boat's centreline), the working preventer is slackened, the lazy one tightened, and the mainsheet made very secure. It is important that all crew are safe from where

841-542: Was adopted for sailboat spars. Aluminium spars are lighter and stronger than their wooden counterpart, require less maintenance and generally hold up better to marine conditions. Aluminium spars are usually associated with fibreglass boats, although one can still find a few early fibreglass 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 fibre . Various hardware

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