This article has multiple issues. Please help improve it or discuss these issues on the talk page . (Learn how and when to remove these template messages)
|
A gybe preventer, preventer, or jibe-guard, is a mechanical device on a sailing vessel which limits the boom's ability to swing unexpectedly across the boat due to an unplanned accidental jibe. [1]
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 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 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 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 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 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 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 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 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 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 the newly working preventer.
Sailing employs the wind—acting on sails, wingsails or kites—to propel a craft on the surface of the water, on ice (iceboat) or on land over a chosen course, which is often part of a larger plan of navigation.
A tack is a nautical term both for the lower, windward corner of a sail and, separately, for the windward side of a sailing craft (side from which the wind is coming while under way—the starboard or port tack. Generally, a boat is on a starboard tack if the wind is coming over the starboard side of boat with sails on port side. Similarly, a boat is on a port tack if the wind is coming over the port side of boat. However, confusion can result when a boat is on a 'run', with the wind coming directly from astern and the mainsail and jib/genoa are on opposite sides of the vessel. Therefore, the windward side is defined as the side opposite to that on which the mainsail is being carried. On a starboard tack the mainsail is carried on the port side. On a port tack the mainsail is carried on the starboard side. It is the position of the mainsail that determines the tack.
A point of sail is a sailing craft's direction of travel under sail in relation to the true wind direction over the surface.
A jibe (US) or gybe (Britain) is a sailing maneuver whereby a sailing vessel reaching downwind turns its stern through the wind, which then exerts its force from the opposite side of the vessel. Because the mainsail boom can swing across the cockpit quickly, jibes are potentially dangerous to person and rigging compared to tacking. Therefore, accidental jibes are to be avoided while the proper technique must be applied so as to control the maneuver. For square-rigged ships, this maneuver is called wearing ship.
A spinnaker is a sail designed specifically for sailing off the wind on courses between a reach to downwind. Spinnakers are constructed of lightweight fabric, usually nylon, and are often brightly colored. They may be designed to perform best as either a reaching or a running spinnaker, by the shaping of the panels and seams. They are attached at only three points and said to be flown.
Running rigging is the rigging of a sailing vessel that is used for raising, lowering, shaping and controlling the sails on a sailing vessel—as opposed to the standing rigging, which supports the mast and bowsprit. Running rigging varies between vessels that are rigged fore and aft and those that are square-rigged.
In sailing, a sheet is a line used to control the movable corner(s) (clews) of a sail.
Tacking or coming about is a sailing maneuver by which a sailing craft, whose next destination is into the wind, turns its bow toward and through the wind so that the direction from which the wind blows changes from one side of the boat to the other, allowing progress in the desired direction. Sailing vessels are unable to sail higher than a certain angle towards the wind, so "beating to windward" in a zig-zag fashion with a series of tacking maneuvers, allows a vessel to sail towards a destination that is closer to the wind that the vessel can sail directly.
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 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.
In a keel boat, a death roll is the act of broaching to windward, putting the spinnaker pole into the water and causing a crash-jibe of the boom and mainsail, which sweep across the deck and plunge down into the water. The death roll often results in the destruction of the spinnaker pole and sometimes even the dismasting of the boat. Serious injury to crew is possible due to the swift and uncontrolled action of the boom and associated gear sweeping across the boat and crashing to the (now) leeward side.
"Man overboard!" is an exclamation given aboard a vessel to indicate that a member of the crew or a passenger has fallen off of the ship into the water and is in need of immediate rescue. Whoever sees the person fall is to shout, "Man overboard!" and the call is then to be reported once by every crewman within earshot, even if they have not seen the victim fall, until everyone on deck has heard and given the same call. This ensures that all other crewmen have been alerted to the situation and notifies the officers of the need to act immediately to save the victim. Pointing continuously at the victim may aid the helmsman in approaching the victim.
A fractional rig on a sailing vessel consists of a foresail, such as a jib or genoa sail, that does not reach all the way to the top of the mast.
Rounding-up is a phenomenon that occurs in sailing when the helmsman is no longer able to control the direction of the boat and it heads up into the wind, causing the boat to slow down, stall out, or tack. This occurs when the wind overpowers the ability of the rudder to maintain a straight course.
The junk rig, also known as the Chinese lugsail, Chinese balanced lug sail, or sampan rig, is a type of sail rig in which rigid members, called battens, span the full width of the sail and extend the sail forward of the mast.
A boom brake is a device designed to control the swing of the boom on a sailboat. The boom brake acts as a preventer when sailing downwind, and can also be used to jibe(US) or gybe(UK) the mainsail in a slow measured action.
A mast-aft rig is a sailboat sail-plan that uses a single mast set in the aft half of the hull. The mast supports fore-sails that may consist of a single jib, multiple staysails, or a crab claw sail. The mainsail is either small or completely absent. Mast-aft rigs are uncommon, but are found on a few custom, and production sailboats.
A sail is a tensile structure, which is made from fabric or other membrane materials, that uses wind power to propel sailing craft, including sailing ships, sailboats, windsurfers, ice boats, and even sail-powered land vehicles. Sails may be made from a combination of woven materials—including canvas or polyester cloth, laminated membranes or bonded filaments, usually in a three- or four-sided shape.
Dismasting, also spelled demasting, occurs to a sailing ship when one or more of the masts responsible for hoisting the sails that propel the vessel breaks. Dismasting usually occurs as the result of high winds during a storm acting upon masts, sails, rigging, and spars. Over compression of the mast owing to tightening the rigger too much and g-forces as a consequence of wave action and the boat swinging back and forth can also result in a dismasting. Dismasting does not necessarily impair the vessel's ability to stay afloat, but rather its ability to move under sail power. Frequently, the hull of the vessel remains intact, upright and seaworthy.
The Marlow-Hunter 37 is an American sailboat that was designed by Glenn Henderson as a cruiser and first built in 2014.
Wing and wing, Wing on wing, Goosewinging or Goosewinged, is a term used to define, in a fore-and-aft-rigged sailboat, the way to navigate sailing directly downwind, with the mainsail and the foresail extended outwards on opposite sides of the boat, forming a 180º angle, to maximize the projected area of sail exposed to the wind. The jib is held out by the clew with a whisker pole, to allow the capture of the maximum amount of wind on the chosen side, without being covered by the mainsail.