Re: [Paddlewise] (none) now Removable bulkheads

Mike O'Byrne" <Heep_at_attbi.com> wrote:
>Anyone heard of removable bulkheads, possibly made of closed cell foam
>or other similar materials? Simply fashion one myself or do they exist
>somewhere? I'm reluctant to cut up my beautiful Coho deck.   Thanks!

In the 1980's we had a removable foam bulkhead as an option for the stern of
our kayaks. I also tried using them in the bow but they were too much of a
pain to place and remove up there. They worked better in the kayaks with a
V-bottom and concave curved (rather than flat) back decks. From my memory of
its shape there I'd guess the Coho should allow a good tight fit. The
hardest parts to get a good seal in are going to be the sharp faceted
corners under the Coho's deck (incidentally we first showed Pygmy's John
Lockwood this facet as a means to help prevent barked knuckles at the hull
to deck joint of a stitch and glue hull many years ago-Cam had already done
this on the Coaster prototype in 1984-85). It is harder to get a good seal
with a removable foam bulkhead on flat decks or on concave or uneven
surfaces like some of our kayaks had. Where the bulkhead would go, we
eventually used filler to fill in that area of the inside indent on the
kayak models that had a ribbed keel on them since it was so hard to get a
good fit there). We finally abandoned all foam bulkhead options (fixed or
removable) when the 2" thick Ethafoam we were using only became available
with a small holes punched through it every 1/2 inch or so and it was no
longer watertight. Something to do with EPA regulations, I heard.

I can offer a few tips from experience. You will need reasonably stiff foam
of about 2" thick (if you place the top of the removable bulkhead in first
and punch the bottom in with your fist like we did) 3" foam would probably
have to go straight in with no tilt (but I have no experience here-so I'm
speculating based on my experience with the 2" foam). You would probably
need minicell foam to be 3" thick to get enough stiffness for the bulkhead
to stay in reliably. Make it slightly oversize and trim them to fit using
the "fit and cuss" method. We cut the Ethafoam with a good stiff bladed
saber saw or an electric steak knife, however, different foam types might
require different tools. I beveled the edges slightly at the top and bottom
(the ones that contacted the kayak first to make it easier to push into
place). Place the release toggle well off center so you can peel it out on
one side rather than try pop it straight out (very difficult to do due to
the "suction"). Use a good big strong backing plate for your toggle so it
doesn't pull though the foam when you are trying to remove the bulkhead (we
used the 4" holes of fiberglass we had cut out of the bow decks for a
Beckson armhole hatch). Do not leave the bulkhead in place during storage as
the foam may become compressed and not seal as well later. In fiberglass the
constant pressure during storage might also distort the fiberglass outward
some (probably not a problem with the even stiffer wood/glass construction
though-and probably a major problem with putting a removable foam bulkhead
in a plastic kayak)

Why not use a sea sock and avoid the need to put a potentially leaky hatch
in front of yourself (as well as behind yourself)? With a sea sock you
probably wouldn't need the foam bulkhead either (at least with float bags or
waterproof gear bags to back the sea sock up), unless you wanted the foam
bulkhead for stiffening the back of the cockpit area for sitting on during
entries and exits. The sea sock avoids the stress riser that even a foam
bulkhead creates (unless it is very soft foam and there fore unlikely to
stay in place if say tumbling in the surf).

Matt Broze
www.marinerkayaks.com



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