Homemade Bosun Chair

Developing rock climbing routes generally means spending lots of time hanging in harness. I try to find good thick adjustable harness but you still get uncomfortable after awhile.

I was on the MEC website when I came across a Black Diamond Bosun's Chair. At first it struck me as odd, but then I realized just how genius it was. Bosun's Chair was originally from the word 'boatswain'. It was a plank used to allows sailors to work on rigging at heights. I used a Bosun's chair when I was a kid on my Dad's sailboat.

Did I mention the Black Diamond product was 80$? I figured I could put something together using some scrap plywood and some newly retired 7mm cord. Here is how I did it.

1. Get a piece of 3/4 inch plywood cut to the dimensions of 6x18 inches. 
2. Using a 3/8 drill bit, drill a hole in each corner about 1 inch from each edge. Have a scrap piece of wood under the plywood to prevent tear-out.
3. Chamfer or round all edges using a hand plane or course grit sandpaper.
4. Sand the inner edges of the 3/8's holes so there isn't a sharp edge chewing into the rope. 
5. Sand the plywood using a random orbital sander. Start at 80 grit and then work through 150 and then 220.
6. Finish the wood with a polyurethane or varnish. This protects the wood and stiffens it.
7. Take 2 pieces of 7mm climbing accessory cord (not the crap you buy in a hardware store) approximately 5 feet in length each.
8. Feed the cord through the holes, one cord on each end, so ends are on the 'up' side of your bosun chair.
9. Tie opposing double fisherman's knot like you would to create a sling or prussit.

1. Tie one side first and place the end of a shoulder sling over the remaining loose end.
2. Finish the second knot, capturing the sling between the two opposing knots.
3.  Repeat the same knots on the cord on the other end of the 'seat', again capturing the other end of the shoulder sling between the knots.
10. Now you will have two loops of cord on either side of the seat. Rotate the cord so the fisherman knots bring the sling to the level of your lower back. The sling provides a backrest.
11. Now to customize your Bosun's Chair.

1. I bought a cheep leather tool pocket (17$) that was the same width as my chair. I put an eye screw on either end of the seat. The eye was just big enough the accommodate the 7mm cord. I threaded a piece of cord through the pocket's 'belt loop' and then through the eye screw on each side, securing it with a simple overhand blocker knot.
2. On the other side, I place 3 eye screws, one on each end and then one in the middle. I thread another piece of 7mm cord through all 3 eye screws and tied it off with blocker knots on either end. This makes 2 gear loops on the opposite side from my tool pocket.

To use the Bosun's Chair, it is very important that this is only meant for comfort and it is not a piece of your safety system. It is all retired cord and slings. Set up your rappel system using your personal anchor system (or equivalent) to extend your rappel devise and a prussit as a back up off your your belay loop. Take the chair and clip the two loops with one carabiner into a loop on your personal anchor system. If it is clipped to low, you will be still hanging in the harness. Clip it too high and you will not be able get into it. It should be just high enough that when you sit on it, your harness becomes slack. If any part of the Bosun's Chair fails, you fall back onto your harness/rappel system.