This is a rarely found 19th C. bosun’s (boatswain’s) chair. 9 in, x 22 in. with original rope.
A very important item of ship’s gear, a bosun’s chair consisted of a hard plank seat attached to a protective rope harness. While seated in the chair, a sailor would be hoisted aloft by use of a pulley system, providing quick access to an area of ship’s rigging that needed attention.
In Clifford Ashley’s Book of Knots there is a drawing of an identically designed bosun’s chair.