I have survived a number of times climbing my masts with my modified boatswain’s chair, made in 2006. Last time I used it was for climbing Ingeborg’s mast, a couple of years ago.
Having grown older since 2006, I made climbing easier by tying something similar to a Prusik loop to the hauling end of that climbing rope. Before each pull, I raise the knot upwards. Then I let a foot step lightly into that loop, and this off-loads my arms at each pull.

Varying diameter of the mast is no issue with this method.

Have a look.
Arne

(PS: When climbing the mast this way, I have kindly  -  and repeatedly  -  been told that I am mad...)

Hello, I climbed once on my mast to recover the halyard ; a rope that wraps twice around the mast and attaches to the harness’s waist belt, and another rope set up the same way below the first one, with a 'pedal' (a loop) for my foot. Then it’s just a matter of climbing step by step: first, I sit in the harness and pull up the pedal’s knot, then I stand on the pedal and pull up the harness’s knot. Thirty centimeters at a time, I gradually climbed all the way to the halyard, then came back down the same way.

Hi all, 

I’m looking at climbing the mast of new to me ‘Mr Fox’. I’m familiar with the method of using two sliding Prusik knots on halyards to climb masts using a harness, but earlier today I noticed that I could use quite thick rope for sliding Prusik knots tied  directly on the Aluminium tapered mast, Has anyone tried this method?