I had start of 5.5m Sea Kayak project on last month.

I need to find Apart Kayak bulkhead information in my sea kayak project stage. My bulkhead marine plywood thickness is 8mm with bulkhead centre plywood is 4mm with extra 330-csm fibreglass for save weight?

What is size of plywood round with filler on bulkhead? (say radial round 2"?)

A 5.5m Sea Kayak stitches & tape plywood design by David Payne is born in Canada and living in Sydney but I wanted sea apart kayak built for storway and lived in housing commission tenant

I put 8mm plywood apart bulkhead in my 5.5m Sea Kayak Stitch-and-Glue design (non-apart kayak) by Australian David Payne also Apart Bulkhead of Sea Kayak Stitch-and-Glue design by Gerry Gladwin at Volkskayaks webpage.

I am not sure apart bulkhead weight is apart bulkhead laminate two of 4mm Plywood thicknesses and total 8mm plus fibreglass CSM lamin