Jibe
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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 boat to the other. For square-rigged ships, this is called wearing ship and involves bringing the ship before the wind with braces carefully controlling the sails.
In this maneuver, the mainsail will cross the center of the boat while the jib is pulled to the other side of the boat. If the spinnaker is up, the pole will have to be manually moved from one corner of the sail to the other. In a dinghy, raising the centerboard can reduce the risk of capsizing during what can be a somewhat violent maneuver.
The other way to change the side of the boat that faces the wind is turning the bow of the boat through the direction of the wind. This operation is known as tacking or coming about.
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[edit] Spelling
While jibe and gybe are both acceptable spellings of the term, gybe is more common in British English and jibe in American English.
[edit] Use
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Jibing is a less common technique than tacking, since a sailboat can sail straight downwind, whereas it cannot sail directly into the wind and has to tack or sail a zig-zag course at alternating angles into the wind. However, many sailboats are significantly faster sailing on a broad reach than running (sailing straight downwind), so the increased speed of a zig-zag course of alternating broad reaches can make up for the extra distance it takes over a straight downwind course. The sailboat will execute a jibe maneuver when it changes course as it zig-zags downwind. Jibing is also used commonly in races, which often use a triangular course marked with buoys; the most direct way of rounding a buoy may be to jibe. A jibe can generally be completed more quickly than a tack because the boat never turns into the wind, and thus a jibing boat's sails are always powered where a tacking boat's sails are un-powered as the bow crosses into the direction of the wind.
Because of the inherent dangers in jibing (uncontrolled, the boom can travel almost 180° with great speed and lethal force), communication with the crew is important. The helm should use three commands when jibing: “Prepare to jibe” indicates that everyone should get in position, ready for the jibe. “Bearing away” (similar to saying “helm's a-lee” during a tack) is used at the start of the evolution when the helm actually applies rudder action to change course. Finally, “jibe-ho” is called when the boom is coming across. If the helm maintains control, maintains good communication with the crew and takes responsibility for the evolution and exactly when the boom jibes, the whole jibe will go more smoothly and be controlled. If the helm is in control, it is possible for them to slow or even stop the jibe if anything is going wrong.
When running (sailing nearly directly downwind), one may 'jibe' only the foresail to the opposite side of the boat from the mainsail. This keeps both sails exposed to the wind resulting in a more efficient use of wind. This technique is sometimes referred to as running "goose-winged", "gull-winged", or "wing-and-wing". When running wing-a'-wing, a light spinnaker pole or whisker pole is often used to hold the clew of the foresail out to the windward side of the boat.
[edit] Dangers
A jibe can be a dangerous operation in a fore-and-aft rigged boat because, as the direction of the wind crosses the boat's centerline, the "old" leeward side of the mainsail and boom suddenly becomes the new windward side, and the sails are always fully exposed to the wind. Load on the sail and mainsheet can remain high throughout the maneuver, and if uncontrolled, the boom and mainsail can swing across the deck with great force, injuring anyone standing in the path of the boom, the mainsheet or its tackle as they sweep across the boat. An uncontrolled boom slamming to the limit of its range may also put excessive stress on the rigging, and can break the boom or standing rigging, perhaps even bringing the mast down. A jibe can also result in a sudden change in the direction of heeling.
To reduce the dangers of jibing on a small boat, the boom is sheeted in and may also be guided across the boat by hand as the direction of the wind crosses the centerline of the boat, and then the mainsail is eased out to its new sailing position. The mainsheet is tightened during the turn to limit the range of movement of the boom (see preventer). When jibing it is usually safer to sail nearly directly downwind briefly before and after the jibe and make a small boat direction change when jibing, so that there is less heeling force on the boat during a jibe. Then you can continue a course change to higher points of sail (e.g. broad or beam reach) after the jibe is complete and crew relocated. Once on the new course, the mainsheet is eased to trim the mainsail. These techniques prevent the boom from swinging unexpectedly.
Accidental jibes may occur when sailing on a course that is running dead downwind if the wind catches the leeward side of the sail. When the wind direction crosses the centerline of the boat, without jibing, the point of sail is referred to as "by the lee" When sailing "by the lee" the outer edge of the mainsail is facing slightly into the wind. Slight changes in the boat heading, rolling motion, or wind direction can cause an unexpected and surprising jibe, suddenly and forcefully flipping the mainsail to the opposite side of the boat. Do not sail "by the lee" except for brief durations (such as to avoid an obstacle), and only when keeping all crew clear of the boom swing and the arc of the mainsheet sweep. See broach, Chinese gybe and death roll.
When sailing dinghies in high winds, a boat can capsize shortly after a jibe due to helmsman error (loss of tiller control) or tripping over the centerboard. It is partly for this second reason that centerboards are often lifted while sailing downwind even in non-planing hulls. The main reason being that a centreboard/keel is not needed for sailing downwind and simply adds to the drag of the hull. Raising the centre-board reduces drag and increases the boat's speed.
[edit] Alternatives to jibing
The term chicken jibe refers to the process of turning a fore-and-aft rigged boat upwind and tacking through more than 180 degrees to avoid having to jibe on a downwind course. While much slower, this technique avoids the dangers of passing the boom across the boat under load. It is the opposite to the practice of wearing ship on a square-rigged vessel, in which the vessel jibes to avoid the problems that square-rigged vessels face when tacking.
[edit] See also
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