Hi everyone,

I am also debating what is the right thing. On the one side I don't believe that the bulhead needs to be that flexible due to the stiffness of the hull - but it may not hurt either to allow for this case. On the other hand it is better to have the stiffer bulkhead for re-entries since it distributes the load much better.

Now I have many options. I want a mohagony finish for the bulkheads. I can just cut the veneer to any thickness. I debated before to go with somewhere between 1/16-1/8 and probably two 3.2oz layers. This would make a nice flexible bulkhead. On the other extreme I am considering a 3/16 western red cedar core and 1/32 mohagony veneer to get the looks I want.

This is difficult to decide. Any more thoughts on the subject?

Andreas

: morn'n Jon, not sure if this is help, with a nod to Tom. I built a Coho and
: used minicell bulkheads. Primarily because I keep collecting chunks of
: minicell and secondarily because I like the capacity for flexing and
: minimal flotation in an unladen boat (very minor issue actually but it
: can't go vertical). It could have been the type of glass layup I used but
: the bottom of the coho flexes a noticable amount, primarily right under
: the seat/floor area so a flexible rear bulkhead made theoretical sense. I
: talked to a fellow that did some major paddling in Florida with a very
: heavily loaded Coho, he wasn't big but the boat was FULL. He really used
: the boat, and noticed cracks in front of the aft bulkhead on the floor.

: Regarding ply bulkheads I'm inbetween the idea of using thin 3mm ply that can
: flex and using 4mm ply that's tougher. Again it's probably more theory
: than real, not much flexing on vertical ply with fillets and glass around
: it. I'd be more tempted to make a perimeter flange of fiberglass tape or
: cloth that the bulkhead would sit within then make small fillets, although
: it's just easier to fillet and glass a little extra at the bottom rear
: flange. So many permutations to obsess over.

: The standard layup is 6oz glass inside and out, for the pleasure of making
: your expedition kayak weigh an extra few pounds you might consider another
: layer of 4oz inside the hull/cockpit extending a few inches behind the
: rear bulkhead up to the front bulkhead with another layer on the outside
: bottom panels. The ironic thing about overbuilding is that the dings
: invariably show up outside the area of reinforcing,,or maybe their
: noticable.

: I made an oval VCP shaped rear hatch, it suffered some bending/impact cracks
: on the center ridge seam over years of rescue practice and occasioanal
: rental. If your rear hatch is particularly long it would be a good idea to
: double the 1 1/2" glass tape on the center ridge.

: You might consider a 1' strip of 3/8 half oval brass for the stern/bow or
: graphite/epoxy soaked strips of dynel at the entry lines. Two layers of
: 6oz glass will disapear in a weeks worth of rough landings in that little
: strip at the stern. I used nearly 8 narrow layers of 4oz. s-glass at the
: stern and bow, it's about 1/8" thick and has held up fine so far.