The unit I build was slightly modified from the unit shown at www.chipford.com. At "Chip Ahoy" Homeport, they mention attaching the crane arms to the forward shroud attachment points. The ones on the Christopher-Jin have clevis pin holes that point fore and aft which would not allow the crane to pivot as shown. So I made aluminum "L" brackets from extruded angle aluminum and attached them permanently under the stanchion bolts. This also allowed me to make the arms slightly longer. (Longer Arms = Greater Mechanical Advantage)
I tested lifting the mast once it was on the Mast Stepper. It was a bit of a pull but it did go up un-assisted. This coming spring (2010) we'll give it a go all the way up.
The other modification we made was to put a pair of triple blocks at the working end. One of the blocks has a becket to add one more layer of mechanical advantage. I wanted to be able to raise and lower the mast while in the water...in the event I decide to try the Erie Cannel which is said to have low bridges.
The forward end of the arm poles are attached to a 1/4 inch, 4"x4", 6 inch long aluminum angle. I bought the aluminum materials from www.onlinemetals.com for under $60. I started with 7 foot long poles and trimmed them to fit. I used stainless steel rivets and hardware. One arm is riveted to the big angle and the other is wing-nutted to allow folding for storage. The "pinch blocks" are made of teak with a hole drilled down between the faces. They are wing-nutted to the big angle.
At the end of the 2009 season I stored the Mast Crane in place, still attached to the Christopher-Jin. It was ready to go to step the mast at the start of the 2010 season.
The mast lifted quite easily with MOMM single-handing the lifting tackle. I stood in the cockpit watching for any line tangles.