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A jackstay is a cable or bar between two points to support and guide a load between those points, or as an anchor to attach something to be constrained along that line. The term is mostly used in a marine context and originated on sailing ships. Note the use of "stay" implies load bearing working rigging. In diving it is also a line to guide the movements of a diver between the endpoints.
Jackstays are used in several maritime applications. These include:
* Support and guidance for transfer of personnel and materials between vessels at sea (
A diving jackstay is a form of guideline laid between two points to guide the diver during a search or to and from the workplace or to support and guide equipment for transport between two points. A downline is a diving jackstay from an anchor point at or above the surface to the underwater workplace used to control descent, ascent and the transfer of tools, materials and other equipment between the surface and the workplace.
Functions:
*Guiding divers to and from the underwater workplace.
*Guiding and supporting equipment and materials to and from the underwater worksite. Where simply lowering equipment or materials to the bottom may not put the load in the right place, a jackstay may be rigged to guide the load, which is loosely linked to the jackstay by a shackle or caribiner which slides along the taut line and guides the load to the correct place. This is both more efficient and reduces the risk of dropping the load on the diver.
*Guiding divers in specific underwater search patterns. Jackstay searches use one or more lines to guide the divers in a search pattern to increase the probability of complete coverage of the search area. Jackstays may be stretched along the bottom or along the hull of a ship for this function. A moveable jackstay may spanned between fixed jackstays to guide the divers along each sweep of the search pattern, then moved by a specified distance along the fixed jackstays by the divers in preparation for the next sweep. In a snagline search, jackstays may be used to ensure that the divers cover the correct area.
A jackstay is a cable or bar between two points to support and guide a load between those points, or as an anchor to attach something to be constrained along that line. The term is mostly used in a marine context and originated on sailing ships. Note the use of "stay" implies load bearing working rigging. In diving it is also a line to guide the movements of a diver between the endpoints.
Nautical applications
Jackstays are used in several maritime applications. These include:
* Support and guidance for transfer of personnel and materials between vessels at sea (Replenishment at sea
Replenishment at sea (RAS) (North Atlantic Treaty Organization/Commonwealth of Nations) or underway replenishment (UNREP) ( U.S. Navy) is a method of transferring fuel, munitions, and stores from one ship to another while under way. First develo ...
), suspended from a traveller block and controlled by lines running in both directions.
* Support and guidance for rescue or transport by breeches buoy
A breeches buoy is a rope-based rescue device used to extract people from wrecked vessels, or to transfer people from one place to another in situations of danger. The device resembles a round emergency personal flotation device with a leg har ...
,
* A rope or rod secured along a vessel's spar
SPAR, originally DESPAR, styled as DE SPAR, is a Dutch multinational that provides branding, supplies and support services for independently owned and operated food retail stores. It was founded in the Netherlands in 1932, by Adriaan van Well, ...
to attach an edge of a sail or the end of a gaff,
* A rope or rod running vertically on the forward side of the mast on which the yard moves.
* A stay for racing or cruising vessels used to steady the mast against the strain of the gaff.
* A line secured at both ends and tensioned, for use as a support for an awning
An awning or overhang is a secondary covering attached to the exterior wall of a building. It is typically composed of canvas woven of acrylic, cotton or polyester yarn, or vinyl laminated to polyester fabric that is stretched tightly over a li ...
.
* Can refer to a safety line for attaching a safety harness
A safety harness is a form of protective equipment designed to safeguard the user from injury or death from falling. The core item of a fall arrest system, the harness is usually fabricated from rope, braided wire cable, or synthetic webbing. ...
to arrest or prevent a fall, commonly used on sailing yachts, and a requirement on racing yachts, where they are used to reduce the risk of going overboard while working on deck. This line should be properly called a jackline. In this application a webbing
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strap is often used as it will not roll underfoot. Also recently used on the yards of square rigged training vessels (wire rope).
Diving jackstay
A diving jackstay is a form of guideline laid between two points to guide the diver during a search or to and from the workplace or to support and guide equipment for transport between two points. A downline is a diving jackstay from an anchor point at or above the surface to the underwater workplace used to control descent, ascent and the transfer of tools, materials and other equipment between the surface and the workplace.
Functions:
*Guiding divers to and from the underwater workplace.
*Guiding and supporting equipment and materials to and from the underwater worksite. Where simply lowering equipment or materials to the bottom may not put the load in the right place, a jackstay may be rigged to guide the load, which is loosely linked to the jackstay by a shackle or caribiner which slides along the taut line and guides the load to the correct place. This is both more efficient and reduces the risk of dropping the load on the diver.
*Guiding divers in specific underwater search patterns. Jackstay searches use one or more lines to guide the divers in a search pattern to increase the probability of complete coverage of the search area. Jackstays may be stretched along the bottom or along the hull of a ship for this function. A moveable jackstay may spanned between fixed jackstays to guide the divers along each sweep of the search pattern, then moved by a specified distance along the fixed jackstays by the divers in preparation for the next sweep. In a snagline search, jackstays may be used to ensure that the divers cover the correct area.
See also
* * * * * *References
{{Underwater diving, divsup Diving support equipment