Alan,

One of the posters here has modified a kayak so that it breaks down into three pieces. I think this is what you are trying to do? Does anyone else recall the thread to this? Alan, if no one responds, try to do a search in the archives.

Your idea of making the bulkheads on either side of the seam sounds good. If the joint fasteners go through where the bulkheads are 8mm thick, it should be good and strong. Reducing the bulkhead thickness to 4mm inboard of the fasteners will save weight.

If I have done the calculation right, your 330gsm (grams per square meter) cloth equates to 9.7 oz/sqyd. Normally a 4 oz/sqyd (136 gsm) cloth is used on each side of a plywood bulkhead. Your cloth is over twice as strong and you probably need the extra strength because the take-apart bulkheads will be more highly stressed than normal bulkheads.

The fillets on your bulkhead to hull joints should be at least 0.25 inches radius if you are fiberglassing the joints. This should allow the fiberglass to go around the corner without causing an air bubble. This is all you need; making the radius larger than that needed for the cloth to go around, just adds unnecessary weight and stiffness. If you are not glassing the corner you will probably want a larger radius to make the joint stronger. The 2 inch radius you mention sounds too large to me. A 1 inch radius of wood flour or micro-balloons should be plenty.

The six 0.25 inch stainless fasteners you mention for the joint sounds good to me. I hope that the guy here that made the 3-piece boat can add more information for you.

Cheers,

Jon

: 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 laminate total 10mm
: said by Gerry Gladwin less my Apart bulkhead weight question-no answer.

: I had check with apart bulkhead plywood 8mm and centre plywood 4mm with
: 330gsm cover and 6 S/S 1/4" or 6.5mm Bolt & nut weight total
: 1.720grams on after 1.900gram in apart bulkhead project stage without 6
: S/S 1/4" or 6.5mm Bolt & nut.

: Can you tell to me for more apart bulkhead information pleade.