Here is a quick sketch showing the components of the ladder I recently adapted for my Ladybug.
This drawing and some more photos focussing on how the basic pieces go together will, I hope, help simplify things for anyone contemplating making a similar ladder.
During previous discussions on this topic, & especially since I posted a whole heap of photos on Duckworks forum, I sensed that the over-riding concern of intending builders was how the hinges were arranged so that the folded ladder ended up neat & flat against the transom. I hope I have answered this here.
As each transom is different, the method of attachment will have to suit its shape in order for the folded ladder to sit flush or as near to flush as possible as the rope will be between the two. I just pull the knots through a little and the thickness of the rope makes little difference. How you make your attachment will be dictated by its shape and size. Ladybug has a very low transom/splashwell with a thickish motor clamping board at the top, so I glued & through-bolted a block as low as possible, that would be thick enough to let the ladder sit flush with the clamping board when folded.
The ladder consists of only a few components which you can see in the sketch & photos:
1. A Main frame which is hinged to the transom & contains the bottom step & is from 6mm ply with solid timber framing.
2. The small frame which is the top step, is also 6mm ply with solid framing that is sufficiently smaller than main frame timbers to allow this step to lie flush inside the main frame when folded. It is hinged to the main frame by a couple of through-bolts. These bolts are really only there for the step to pivot & to locate it at the top of the main frame as it will be held hard in place when you put weight on the ladder. Put a radius on the top corners of the side framing so they will pivot.
3. Transom mounting block if needed.
4. Large strong hinges & an assortment of through-bolts & screws sufficiently large for the job.
5. Strong 6mm rope.
6. Ocky strap or bungee for retaining folded ladder. Make sure you can reach this strap from the water.
The sizes of materials I have indicated are what I feel will suit my needs & should be varied for your own application.
I will post another collection of photos in Duckworks forum under Ausie Ladybug which show what I am trying to explain here.
P.S I sent Jim a copy of my submission to which he replied that he liked & mentioned ease of release from the water by someone who is not a strong swimmer. I said I had a few other release ideas & would look at testing them.
These pics show the release I will stick.
This is my reply to Jim.
Here is option #2 which I will stay with.
Whipped up a small jam cleat & screwed/glued to back of main ladder frame, drilled hole in transom near ladder rope hole & fitted 6mm rope of appropriate colour with figure 8 knot on end. When ladder is folded against transom, the white ladder rope forms a soft buffer so no need for bungee to keep enough pressure on ladder to stop rattling. If the red rope comes loose while sailing, so what!.... the ladder will simply trail until you re-cleat it. The pics show it all.
Simplest solution I could think of & easily adapted to any transom.
Go make your ladder!