Guide to Bosun’s Chair Systems (Rope Descent System)

  • Worker on a Bosun's chair using suction cups to stabilize. 

Window Washing is often performed with either a bosun’s chair system (boatswain chair system) or suspended platform in conjunction with Pro-Bel rigging equipment (such as anchors, davits, outriggers, etc.).

In OSHA, a bosun’s chair system is referred to as a Rope Descent System (RDS). Read on for a quick RDS guide as outlined in OSHA 1910.27 (Scaffolds and rope descent systems)/ANSI I-14 (Window Cleaning Safety Standard). 

Link for Canadian version here.

A bosun’s chair is a device designed for one person seating and utilizes one rope for suspension and a second rope for safety/lifeline; both lines are directly tied back to separate and independent safety roof anchors. The alternative to an RDS/Bosun’s chair is a suspended platform, which is intended for 2 workers and can be either permanent or portable. A permanent platform is dedicated to the building.

Bosun’s Chair/RDS Usage Restrictions

OSHA allows the use of rope descent systems up to the height of 300ft (91m).  Between 130ft and 300ft, window washers are required to use stabilization; this is typically achieved through the use of suction cups.

Suspended platforms are used most often in conjunction with Pro-Bel Davit systems located on the roof, podium, or sometimes balconies.

Pro-Bel Safety Anchors

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