I looked at scaling down plans of a small dinghy I had built. Designed by Joel White and called the Nutshell Pram, it had a flat bottom and three side-planks making it both stable and relatively easy to build. At first glance, these old imperial-measurement plans seemed ideal to convert into a cradle.

The original hull had a laminated mid-ship frame and a prominent internal fore-keel that would have made sleeping aboard quite uncomfortable. But as it was not going to be a seagoing boat, the frame was left out and the fore-keel modified to reduce the head-hitting potential.

I settled on a half-sized model of the 7' 7" (2.3 metre) original which, although in hindsight was a bit large, was less of a headache to scale. As my tape measure and my brain work better in metric, I wore out the buttons on my calculator plans converting all the measurements. For materials, I used 12 mm marine ply for the bow and stern and 3 mm marine ply for the bottom and side.