Cutting Limbers after the fact.

I played with a tiny ratchet driver and a 6mm auger drill bit. I clamped a scrap batten to a work bench, and I can make a 6mm hole in the batten about 1mm from the bench. This will do just fine. So when the hull is turned I'll do the job on the three battens. I will probably have to cut the auger short, and glue on a socket to the end so that I can fit it between the battens, but that's no big deal.

I will also reinforce the battens on both sides with an extra 1/2 inch from the transom to the next frame. Since these will be flat surfaces, I'll use Balcotan (Marine PU) for the Oak. Previous tests show it works just fine. My test lamination has been knocking about in the garden and in the shed on and off, unpainted for 2 years and it's still solid.