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/Rope Descent System 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.


Image
Pro-Bel Safety Anchors


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