Those skylarks are all takes on the original nutshell, designed by Joel White. Unfortunately like the local copy dont quite look as good.
For our Nutshells we did a bit of FAA and reduced the thickness of most bits knowing that they would be glassed with 6oz .
So built out of Gaboon ply the hull glassed without paint is under 20kg . they are meant to be 7'7" long -though mine ended up as 7' 8" .
Because of the hull shape she stays dryish inside except for extreme conditions, I have seen her clear the water in 45 knots on the nose but never flips, likewise with our keels they tow straight. Rowing ashore she takes four 100kg plus males and you arrive dry!
I may still have the laminating jigs at home and building frame.