I'm going to summarize what I used, some good instructions, what I did and observations from the first climb.
List
Black Diamond Momentum Climbing Harness
Good Old Larikis Chest Harness with 2 D rings.
7mm x 30' of Nylon line for Prusik & Bachmann knots
1" x 30' of Climbing Tubular Strapping
(3) Screw locking Carabiners
The most helpful instructions that I followed are
TRR Skill: Purcell Prussik Building | Swiftwater Rescue
Which gives dimensions based on height for making the two foot strap/prusiks and provides drawings for how it works.
What I did was fit the climbing harness and put on the Larikis chest harness, then tie a close figure eight (see photo) through the climbing harness leg strap loop and the belt loop with a short length of 7mm line. Then using the end of the line I tied a tight bowline and two half hitches through the two D rings in the chest harness and capturing the Carabiner that I screwed closed around the two chest harness D rings.
For the foot climbing
gear I made up two Prusik loops of 7mm. Initially the foot strap loop was tied with a simple overhand knot that is followed from the other side and adjusted to the right length before setting it at the end. After the strap loop is made I tied a prusik knot as per instructions for my foot and then attached to the prusik loop with a clove hitch. I checked everything for height. The long foot strap should end at your sternum and the short one at your hip bone (without a prusik knot tied in the loop).
To prep the halyards I brought each halyard down to the vang bail on the mast and tied a bowline. Then I cleated the uphaul side of the halyards and brought the tail down to the vang bail on the mast and tied that tight with a bowline for safety. This was done for the two "foot" halyards. (topping
lift and main halyard). The bottom of the stationary climbing line should be tightly secured at the base as this helps to stabilize your legs while ascending (climbers call it
single line SLT).
To climb the mast what I used was the boat's 5/8" staset main halyard and the 1/2" staset topping
lift, one leg + bachmann tie for each line (see photo). Then I had a short prusik loop clipped into my chest harness carabiner with the prusik knot tied on the 5/8" main halyard, this was intended as my "safety". I kept that pushed up with every step up, so that if I slipped for some reason there would be a safety.
Then as an extra safety I tied the spinaker halyard to my chest Carabiner with a bowline (don't use the shackle). My wife then pulled this up as I ascended with it wrapped 5 times around the mast winch. Sometimes she cleated it.
My Experience
This was an effective way to climb the mast, but it was work, and there are some considerations which I was not aware of. As you ascend if you are not careful your legs can splay out, this is a little scary, as if the chest safety prusik is not pulled up enough or does not catch on the halyard for some reason, you could end up upside down held by your feet, or worse with the foot loops releasing if they are not tight. This is why it is best to have the chest prusik and the
spinnaker halyard as safeties (at least two). If my wife were not below tightening/belaying the spinnaker halyard, I would have to have two chest prusik loops and knots, one to the fixed spinaker halyard.
The next climb should be easier if I slide the chest safety prusik up and then sit in the harnass, adjust one leg bachmann tie upwards and then stand up then stand up in that loop. Then pull the chest prusik up and sit in the climbing harness and do the same with the other leg. What I did was simply go from leg to leg sliding the chest prusik up while stabilizing myself by grabbing the mast. Also I found that it was easiest to clamp my legs to the mast and make my weight as close to directly on top of the weight bearing foot as possible, otherwise your foot will wave around and you could loose your footing so to speak. This is why it is helpful to have the halyards you are climbing with, tied down at the bottom tight as possible.
Once I got past the spreaders, taking a brief rest, and up to the top, I had a 10' length of line that I threw over the top of the mast and used to hoist myself that last 5" through my chest carabiner. I tied it and was up there balanced with the climbing harness and two foot straps for about half an hour removing the masthead light and testing the
wiring. I was reasonably comfortable and would shift weight, but my arms got tired because the light bolts had allen wrench sockets that I did not anticipate. I should have had allen wrenches.
Take a long light line with you to let the light or
gear or tools down or up and/or have a good bag for this stuff.
Next time I go up, I will remember to sit in the climbing harnass before taking another step.