I've puzzled over how to answer your question. The hardware on Zygote's hinged ladder is just the sort of magic that Sam L. Morse Co. (meaning, in Z's case, the team of Dick McComb and Tommie Whisler, with input and executive function from Roger Olson) did and which I take for granted. I've looked through my photo file, and the few that show the companionway ladder do not show detail.
Let's start with a few advantages of the SLM Co. hinged ladder:
* it's removable when needed (the hinge pins are toggle pins aka drop-nose pins, and so can quickly be withdrawn) but also locked in place (see below);
* in the up position, it acts as a security device, impeding entry into the cabin by the ill-intentioned;
* in the up position, you have full access to the engine room etc.
To control the weight of the ladder (and for other advantages) the ladder on Z does not run full length to the cabin sole. Instead the ladder only runs to the top of a battery box. That box holds (in Z's case) two of Z's five Lifeline AGMs).
To get to the fixings:
* on the overhead, in just the right place, is a bronze eye strap. Held to the overhead by two bronze fasteners that I've not undone. I assume they are screws that bite firmly into the coachroof. I don't think they are through-bolts.
* on the outboard side of the starboard foot of the ladder is another bronze eye strap that
* captures a bronze swivel-eye boat snap for which I do not know a better technical name (so I'll instead point you to the West Marine page: [www.westmarine.com
] Should you know the name for that particular boat snap, who designed it, and if it was patented, please tell me!)
* and a sliding bar latch (which I have also taken for granted and so for which I do not have a clear technical name) that locks the ladder to the top of the battery box (so that, should Z be unlucky enough to be inverted, the ladder stays locked in place).
Lifting and lowering the hinged ladder are practised moves after 19 years. Unlatch the ladder, lift it up, trigger open the boat snap, and let jaws of the boat snap close around the overhead eye strap. Reverse. Repeat.
Couldn't live without it.
BCC 116 Zygote,
Scarborough Marina, Moreton Bay, Queensland, Australia