Lot of good advice here. I have always used to climbing Ascenders. One for my harness and one for two foot loops. I can get up and down the mast solo by using the ascenders on two separate ropes, or just using the foot sling ascender to stand up while my wife takes in the slack on the seat harness ( no cranking the winch handle needed).
The double foot sling means I can comfortably stand above the height of the mast to work, or sit in the harness to rest.
I also take at least a be 8ft tape climbing sling with me. If something broke or jammed you can use the sling as a prussik round the mast to transfer your weight onto.
Two ascenders and a home made double foot sling is way cheaper than some of the commercial stuff and the ability to work above the mast height is a boon.
Ocean Hobo SN96