I did not plane them down to get the bend as suggested, instead I rigged a wallpaper steamer to a PVC pipe and steamed the ends of the timber, it seemed to work ok and I guess that if I left the timber in the steamer for an hour or so then I would have got the bend all the way to the end.
I think if I was to do it again I would make a former to clamp the steamed timber up therefore not forming it on the planks and adding any undue stress to the edges, if using shorter lengths necessitating a scarf joint somewhere then four ends could be steamed and clamped all at once, this would make life very easy and make a neat job that could take a fancy breasthook perhaps slotted into the middle of the inwale.
The inwale was held with quick clamps and fixed with glue then screwed at 150mm centres from the outside of the planks (75mm centres where it starts to bend up) the screws heads will be hidden by the outwales but could have been filled and painted anyway, the outwale will be screwed through to the inwale with the screw heads probably sunk and plugged.
timber scribed onto the top of the Inwale
I am thinking that the craft is quite flimsy and as I will be using it in the sea I think it would be wise to get some more resin and fillet any gaps on the outside then tape all of the outside seams, yet more expense and further delay but I think time spent now will avoid any issues in the future when I least need them