Bill,
Thanks for the reference to the Wichard site. They make great products.
There is a rather radical difference between my boarding ladder and the one pictured on the Wichard page.
The Wichard ladder has a single point of attachment, and uses webbing steps that resemble mast steps. From the photograph on the Wichard page, the topmost step is somewhat below the sheer line.
In the system that I designed and built specifically for my Ariel, The ladder is located adjacent to cockpit at the best place to board the boat from the water, since the hull is fairly vertical there, and there are satisfactory adjacent hand holds on deck (deck-level lifeline terminals, and teak coaming boards). The ladder attaches to two through-deck-mounted eye bolts on deck, which are approximately one foot apart (the length of the ladder rungs)
My emergency boarding ladder has a yellow lanyard with a loop sewn into the end. That lanyard is suction-cupped to the outside of the hull, so that it won't blow back up onto the deck in the wind. As long as the suction cup is wet, it seems to stay fixed on the hull beneath the rub rail during a sail, even when the rail is buried.
When one pulls downward on the lanyard, the ladder unrolls. Standing on the bottom rung of the ladder will place a crew member at a level where the toe rail is at slightly above knee level and will provide the crewmember with two handholds.
There are three rungs on each ladder. The ladder rungs are made of PVC pipe with 1/4 inch Dacron line threaded through them. The top step is just below the sheer line. The ladder is attached to the through-deck bolted eyebolts at the forward and aft edges of the boarding steps by carabiner. The ladder is packed inside a perforated soft plastic sheet, which unrolls to protect the hull when the ladder is in use and serves to aid in rolling and securing the ladder.
I do not at present have any photos of the ladder in its deployed state. I will endeavor to take some photos and post them later.