BarelyAwake wrote:
Thanks, guys, for your input. I had intended to use one of the halyards as
a safety belay. I've seen photos of men at the top of a mast, held by one
line and no backup. This seems foolish, especially considering that there
is always another halyard just sitting there, waiting to be used as a
backup. I like the idea having the harness or bosun's chair attached to a
primary winch serving as a method of descent. Attaching the bosun's chair
to one ascender and a loop for the feet to the other ascender seems like a
great idea for a lazy, middle-aged man like me! I'll give these methods a
try.

Having climbed miles of rope and descended the same (during caving) and
also climbed my mast quite a few times, I offer the following. You do
not want a descender, the probability of making a mistake in going from
ascending to descending is too great. You CAN use ascenders to descend
but as someone else pointed, they are spring loaded so that you must
reach down and hold the cam open while you push it down. You also have
to make sure you dont push it too far down. There is nothing like
trying to put your weight on a sling that is too far down.
Instead, I suggest the use of Prusik knots. They are free and work
very well. To ascend, you slide the knot up and it will rarely slide
back down unless you "break" the knot first. When you "break" the knot
to descend, they grab quickly when you put your weight on them. I
suggest the use of three knots instead of two. You should have two
prusiks on your chair for safety. This is true even when using
mechanical ascenders. With only two ascenders, if your chair ascender
fails, you can ebd up hanging by your heels, uncomfortable and fatal if
you have nobody to let you down.
Any site about vertical caving can give you pointers about making your
own prusiks and ascender safety. ALWAYS, ALWAYS, ALWAYS use a back-up
rope (the other halyard). Your halyard has been there for probably
years going over that sheave. Do you really want to trust your life
only to it?