[Paddlewise] bulkhead

Patrick - Others have already told you how to do this. 

A couple of thoughts - First, a non-idea which seems crude, but which works
pretty well to start making your cardboard template, if you're not comfortable
with taking the curve of the boat by measuring: if you have access to a thick
strip of lead, such as might have come from an old plumbing pipe, you can lay
out that strip in the bottom of your boat and take a nice fair curve from it,
then transfer that to your cardboard template. Julio says a wire will do, for
this - I haven't tried that, but I'd think you'd need a pretty thick wire.
You'll need to do this in 2-3 stages, marking the place where you "measured"
carefully, on your boat, on the strip, and then on the template each time
(bilges, deck surface, etc). It sounds crude, and maybe it is, but it can save
you some time.

A much more elegant and accurate way is to take the curve directly from the
boat by measuring distances each inch or so. This is probably best done by
choosing a "horizontal" plans, marking it on the boat, and then measuring
vertically at your intervals. These measurments can then be transferred to
your template. Use a batten or a french curve to draw a fair curve from your
measurements on the template. Make your template, try it in the boat, adjust
dimensions as needed, and cut your bulkhead.

I've preferred to use plywood rather than fiberglass board, maybe just because
I have plywood around. Four mm okume, reinforced with a layer of 6 oz glass
cloth on each side, is very strong. 1/4 inch marine plywood is more readily
available, and also makes a good bulkhead - again, I've reinforced it with
glass cloth both sides.

The plywood bulkhead is fixed in place with 2 or 3 inch glass tape all around.

Like everyone else, I've used 3 inch closed cell foam (sold by NOC and others)
as bulkheads. It's easier to shape, little errors in configuration can be
corrected as you jam the foam in, and it's slight compressibility avoids the
"stress riser" you otherwise get from a hard bulkhead. (My Romany 16 got
rammed into a rock while surfing a couple of years ago, and would have had no
damage at all except that the aft bulkhead acted as a stress riser and the
boat cracked just behind the bulkhead. All fixed now, thank goodness.)

The closed minicell foam is sealed in with 3M 5200 or similar sealant, and it
stays there forever! The sealant does take a week or so to cure completely,
though.

BTW - My small experience suggests that you'll never notice the difference in
retained cockpit water in you orient the aft bulkhead just a few inches behind
the seat, and orient it vertically. I think a vertical orientation makes the
bulkhead easier to fit, and I've been pleased with how well the boat empties
out during rescue practices..





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