A boatswain chair or bosun chair is a wooden board slung by a rope and used to sit on while working at height or over the side of a ship. Boatswain chairs should only be used where the work is relatively short duration and light work. They should only be used where it is not practicable to provide a working platform.
A person in a boatswain’s chair is extremely vulnerable. They have suspended high above the ground. Bosun chairs are often used with vertical lifelines. It is mandatory to wear a full-body harness when using the chair. There are two independent lifelines that are also needed one for the chair and one for the user.
A boatswain chair is used for supporting and hoisting a single person in a sitting position. The chair size is 60×30 cm, with a 25 mm thick plank. Cleats extending in front to at least 23 cm should be securely fixed under the chair at both ends. The chair is supported by a suitable sling passing through the four corner holes in the chair for proper stability.
The suspension rope is fixed to overhead support or passed through a pulley block fastened to such support. The free end is secured to a conveniently accessible anchorage and the person in the chair must wear a safety belt, the lifeline of which is secured to the tackle supporting the chair. In case the person requires doing welding or cutting he should not use a fiber rope sling.
In exchange, the bosun chair or boatswain chair does not allow the freedom of movement necessary for climbing, and the occupant is generally hoisted or lowered into place using the rope alone. Some bosun chairs consist of little more than a short plank and a suitable set of ropes to suspend it from; these are usually used with a separate harness in case the user should slip off the plank.
As well as on ships and boats where they originated, bosun’s chairs are also used for working at height on buildings and other structures. In commercial window cleaning, the term ‘bosun’s chair’ is used for other devices suspended from a rope and equipped with seat boards, such as controlled descent apparatus.
The risk assessment should cover rescue procedures should an emergency occur. The installation and use of a boatswain’s chair must be supervised by an experienced and competent person.
Boatswain chair or bosun chair safety
- Inspect the chair regularly.
- Check cut or worn threads to tringle attachment points.
- The operator must be wear full body harness.
- The operator must be a competent person.
- The Boatswain Chairs shall be operated as per the manufactures and its competent installer’s guidelines.
- Only properly trained and competent operatives should be permitted to use them.
Boatswain chair Rigging
In the construction industry, a boatswain’s chair should always be rigged with a pair of single sheave pulley blocks, having a safe working load of at least 225kg. Outriggers and other supports must be strong enough, and be securely fastened down.
Boatswain chair details
- If the chair has a single central leg or suspension member, this should be without sharp bends and be securely fixed to the seat as far back as practicable, so that the user sits with one leg at either side.
- To be provided with a safety harness to prevent the occupant from falling out.
- The back and the suspension member should be placed so that no-one can fall out.
- The suspension point must be at least 500 mm above the seat, with provisions for suspension. No part should be able to become detached.
- Be made for a safe working load of 115 kg. A proof test of 150 kg is recommended.
Protection of the operator while using boatswain chair
When the risk assessment identifies that work from a boatswain chair will take place above areas where people may be present, adequate protection must be installed to prevent them from being injured from falling equipment or materials.
Boatswain chair hooks
Hooks should be fitted with a spring-loaded device to prevent the displacement of the load.
How to use a boatswain chair?
Place the left leg through the left leg loop, followed by the right leg through the right leg loop.
Pull the seat up to around the hips, holding on to the spreader bar.
Place your arm through the shoulder straps, using the loops pull them right.
Take the rope and pull it through the central connection. Ideally use a bowline knot for your safety.