Re: [Paddlewise] how thick are figerglass bulkheads?

Make the bulkhead laminate thinner than the hull and deck laminates unless
they need to be structural (footbrace, pump support, etc.). That way if you
run over something like a rock or a snag with the hull the (that causes the
hull to flex as it slides over the object) bulkhead will give before the
hull does when the rock or snag runs into the stress riser caused by the
bulkhead. Because the hull is likely to be more flexible behind the seat
than in front of your feet where it is narrower this is more important for
the rear bulkhead.

Do not use just two layers fiberglass cloth for the bulkhead. If you do you
will likely have a problem with pin hole leaks where the cloth layers line
up and little air bubbles can be hard to remove during lamination. In fact
the bulkhead is likely to look more like a sieve if you use only cloth. It
is far better to use one layer of fiberglass mat in the bulkhead as a
sealing layer. So one layer of 8 ox. cloth and one layer of 3/4 oz mat would
make a thin lightweight bulkhead. To beef it up some you could use another
layer of 8 oz. cloth (to sandwich the mat between two layers of cloth) or
use 1.5 oz mat for that layer in the two layer system. The more mat used the
more brittle the bulkhead will be (on a pound for pound basis). Brittle or
flexible is not necessarily a bad thing in a bulkhead as it is the part you
would rather have break when faced with enough force to bend or break
something on the boat. some have angled the bulkhead so it is not vertical
for various reasons. This may also help it flex better and not be as much of
a stress riser than if it was vertical.

Matt Broze
www.marinerkayaks.com
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