A bosun's chair is a type of supported rigging harness, originally designed for use on boats but also employed in other industries as well. The bosun's chair is both a convenience and a safety tool: convenient because it keeps the hands free for work, and safe because it prevents potentially dangerous falls from heights. On ships, a bosun's chair is used for working aloft in the rigging, often for long periods of time. In other industries such as exterior maintenance for buildings, bosun's chairs are frequently used because they are affordable, safe, and easy to rig.
The name “bosun's chair” originates from the bosun or boatswain, the petty officer on a ship who is in charge of the rigging crew. While the bosun rarely goes aloft, the bosun's chair would be part of the equipment and supplies that the bosun is in charge of and expected to maintain. Access to the rigging of the ship's sails is crucial during a voyage, and a bosun's chair allows sailors to quickly reach the area of the rigging that needs attention.
A very basic bosun's chair has a hard plank seat attached to a harness. The sailor clips into the harness, using the plank seat for support, and is hauled into the rigging by use of a pully system. More advanced bosun's chairs actually resemble chairs in design, with a supportive back and sides like a sling that is more comfortable to be in for long periods of times. These chairs are also usually adjustable, so that the rigger can find the right balance point for comfort and safety while he or she works. Modern bosun's chairs also include additional clips for a second lifeline, in case the primary rigging harness fails for any reason.
In many ways, a bosun's chair is similar to a climbing harness, and it uses the same principles. In both cases, the individual straps in, often with thigh and waist straps to prevent slippage. However, a bosun's chair usually has a rigid seat, which distinguishes it from a climbing harness. A bosun's chair also does not permit the range of movement that a climbing harness does: sailors usually have to be hoisted aloft, for example, because they cannot climb while seated in the bosun's chair.
Like other equipment designed for working in heights, a bosun's chair should be carefully maintained to prevent equipment failure. It should always be stored in a cool dry place, and checked frequently for mold, sun damage, and other signs of wear. If straps have begun to fray, they should be replaced. The ropes used to raise the bosun's chair into the rigging should also be regularly inspected and cared for.