I've been a busy beaver walrus making little models of the coracle to be.
Easy done it is too. While I used my proposed plastic sand bags building technique to construct the SS Enamel, the other two in the fleet were simply papier mache construct over kitchen bowls.
With SS Penetrol I also laid down a layer of linen/cotton cloth, but besides that one feature, both it and SS Acrylic are all paper and glue. I experimented with SS Penetrol by laying down Penetrol strata as I built up the layers to see if I could adhere paper/glue layers on top of Penetrol ones. Penetrol is an oil mix designed to prevent water ingress by soaking into the material and displacing space that water could occupy.It is used extensively in the marine environment. It is simply rubbed on/rubbed off a few times.
SS Acrylic uses a very ordinary inside/outside Acrylic paint with 4 coats on the outside and two coatings on the inside.
SS Enamel is such a mix of experimental techniques that it is hardly a scientific excursion -- so let's treat it as "Control". Enamel paint, main paper layers and bamboo framing.
My hope is that later I can remove the ships and do an autopsy on their innards to see where and how water, if it did indeed soak in, entered each hull. My problem is that after several hours there's no soaking and I'll need to add the weight of cargo to the vessels. Stones perhaps.
I also received in yesterday's mail The Cardboard Boat Book which is an idiosyncratic manual on how to.... construct a boat from cardboard.I was interested in a few engineering concepts and the book is a useful reference in that regard.It also relies on masonry coatings and dry wall adhesives to adhere and protect the build.
The discussion in the book makes me think that the coracle shape suits paper construction as the gravitational forces are spread across the upside down dome. But when I start to add my 100 kgm frame on top of papier mache sitting on water, while the craft's centre of gravity may shift and move along the hull, the concentrated point of my weight at the foot fall will stress the hull at that locus. So while I may be able to fill the coracle with many kilograms of wet sand or soft rocks and sail it easily, a human creature with arms and legs sticking out, moving about and standing on its 'deck' is going to be another challenge all together.
