Backstay
Encyclopedia
On a sailing
vessel, a backstay is the piece of standing rigging
that runs from the mast
to the transom
of the boat, counteracting the forestay
and jib
. The backstay is an important sail trim control and has a direct effect on the shape of the mainsail
and the headsail
.
A permanent backstay is attached at the top of the mast and may or may not be readily adjustable.
In a masthead rig
, tensioning the permanent backstay will directly tension the forestay. This control is used to adjust the amount of "sag" in the headsail. In a fractional rig
, tensioning the permanent backstay will have two effects: First, the forestay is tensioned (controls sag in headsail) and second, the mast bend is increased, particularly in the upper one-half to one-third of the mast. Increased mast bend tends to reduce the draft (camber
) of the mainsail.
A running backstay always attaches to the mast at a point below the top of the mast and is generally used in conjunction with a permanent backstay. Running backstays are found on both masthead rigs and fractional rigs. There are some rigs for which running backstays may be used without a permanent backstay. This occurs most often where the mainsail has significant roach. Gaff rigged
boats invariably have running backstays with no permanent backstay. In both of these cases the mainsail extends aft of a line from masthead to stern, and so a permanent backstay would interfere with the operation of the sail. As a direct consequence of its attachment point (below the top of the mast) a running backstay is always adjustable, because it must be manually engaged and disengaged during every tack or jibe
. Adjusting the tension on the running backstay has two effects: First, the forestay is tensioned (controls sag in headsail) and Second, mast bend is reduced (the mast becomes straighter). The overall effect of tensioning the running backstay is a deeper mainsail (more camber) combined with a reduction in headsail sag.
If the running backstays leads to the mast where the forestay attaches, the effect of tensioning them will be as follows. Again the forestay is tensioned reducing sag in the headsail and second, mast bend is increased with flattening of the mainsail as a result. Both effects are desirable as the wind increases.
Backstays are generally adjusted by means of "block and tackle
", hydraulic adjusters or by lines leading to winches.
, accomplished by placing structural backstay insulators at either end of the backstay.
Sailing
Sailing is the propulsion of a vehicle and the control of its movement with large foils called sails. By changing the rigging, rudder, and sometimes the keel or centre board, a sailor manages the force of the wind on the sails in order to move the boat relative to its surrounding medium and...
vessel, a backstay is the piece of standing rigging
Standing rigging
On a sailing boat, standing rigging generally refers to lines, wires, or rods which are more or less fixed in position while the boat is under sail. This term is used in contrast to running rigging, which represents elements of rigging which move and change fairly often while under sail...
that runs from the mast
Mast (sailing)
The mast of a sailing vessel is a tall, vertical, or near vertical, spar, or arrangement of spars, which supports the sails. Large ships have several masts, with the size and configuration depending on the style of ship...
to the transom
Transom (nautical)
In naval architecture, a transom is the surface that forms the stern of a vessel. Transoms may be flat or curved and they may be vertical, raked forward, also known as a retroussé or reverse transom, angling forward from the waterline to the deck, or raked aft, often simply called "raked", angling...
of the boat, counteracting the forestay
Forestay
On a sailing vessel, a forestay, sometimes just called a stay, is a piece of standing rigging which keeps a mast from falling backwards. It is attached either at the very top of the mast, or in fractional rigs between about 1/8 and 1/4 from the top of the mast. The other end of the forestay is...
and jib
Jib
A jib is a triangular staysail set ahead of the foremast of a sailing vessel. Its tack is fixed to the bowsprit, to the bow, or to the deck between the bowsprit and the foremost mast...
. The backstay is an important sail trim control and has a direct effect on the shape of the mainsail
Mainsail
A mainsail is a sail located behind the main mast of a sailing vessel.On a square rigged vessel, it is the lowest and largest sail on the main mast....
and the headsail
Headsail
A headsail of a sailing vessel is any sail set forward of the foremost mast. The most common headsails are staysails, a term that includes jibs and the larger genoa...
.
Types of backstays
There are two general categories of backstay: The permanent backstay is attached to the top of the mast. The running backstay is attached about two-thirds of the way up the mast (sometimes at multiple locations along the length of the mast). In general, most modern sailboats will have a permanent backstay and some will have a permanent backstay combined with a running backstay. Backstays are not always found on all vessels, especially smaller ones.A permanent backstay is attached at the top of the mast and may or may not be readily adjustable.
In a masthead rig
Masthead rig
A masthead rig on a sailing vessel consists of a forestay and backstay both attached at the top of the mast.The Bermuda rig can be split into two groups: the masthead rig and the fractional rig. The masthead rig has larger and more headsails, and a smaller mainsail, compared to the fractional...
, tensioning the permanent backstay will directly tension the forestay. This control is used to adjust the amount of "sag" in the headsail. In a fractional rig
Fractional rig
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....
, tensioning the permanent backstay will have two effects: First, the forestay is tensioned (controls sag in headsail) and second, the mast bend is increased, particularly in the upper one-half to one-third of the mast. Increased mast bend tends to reduce the draft (camber
Camber
Camber may refer to a variety of curvatures and angles:* Camber angle, the angle made by the wheels of a vehicle* Camber thrust in bike technology* In the steel industry, the concavity of rolls...
) of the mainsail.
A running backstay always attaches to the mast at a point below the top of the mast and is generally used in conjunction with a permanent backstay. Running backstays are found on both masthead rigs and fractional rigs. There are some rigs for which running backstays may be used without a permanent backstay. This occurs most often where the mainsail has significant roach. Gaff rigged
Gaff rig
Gaff rig is a sailing rig in which the sail is four-cornered, fore-and-aft rigged, controlled at its peak and, usually, its entire head by a spar called the gaff...
boats invariably have running backstays with no permanent backstay. In both of these cases the mainsail extends aft of a line from masthead to stern, and so a permanent backstay would interfere with the operation of the sail. As a direct consequence of its attachment point (below the top of the mast) a running backstay is always adjustable, because it must be manually engaged and disengaged during every tack or jibe
Jibe
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...
. Adjusting the tension on the running backstay has two effects: First, the forestay is tensioned (controls sag in headsail) and Second, mast bend is reduced (the mast becomes straighter). The overall effect of tensioning the running backstay is a deeper mainsail (more camber) combined with a reduction in headsail sag.
If the running backstays leads to the mast where the forestay attaches, the effect of tensioning them will be as follows. Again the forestay is tensioned reducing sag in the headsail and second, mast bend is increased with flattening of the mainsail as a result. Both effects are desirable as the wind increases.
Backstays are generally adjusted by means of "block and tackle
Block and tackle
A block and tackle is a system of two or more pulleys with a rope or cable threaded between them, usually used to lift or pull heavy loads.The pulleys are assembled together to form blocks so that one is fixed and one moves with the load...
", hydraulic adjusters or by lines leading to winches.
Backstays as antennas
On modern ocean going yachts, the backstay is also commonly used as an antenna for Marine SSB radios and/or an amateur radioAmateur radio
Amateur radio is the use of designated radio frequency spectrum for purposes of private recreation, non-commercial exchange of messages, wireless experimentation, self-training, and emergency communication...
, accomplished by placing structural backstay insulators at either end of the backstay.