Hi T, I reduced a Guillemot Night Heron (originally 18') to 16' about 5 yrs ago, I live in Florida and paddle mostly in coastal mangrove and mangrove tunnels which require tight turns and maneuvering.I have built both the 18' and the 16' Night Heron and found my best paddling was with the 16' boat, I kept the cockpit in the same location as the 18', for the strongback I placed the bow and stern forms at 16' then measured between the notches and that was the length of the strongback this made the length just over 16' because of the built up bow and stern strips. Have fun with your build and send photos. Nick R.