Re: [Paddlewise] Plastic Bulkheads

> > David Seng wrote:
> >   I'm wondering why you want to remove the existing bulkhead (I'm
assuming that it's watertight).  Couldn't you simply "beef up" the existing
bulkhead
> <snip>
> 
> Thanks Dave. That was my original intent, but after I got the plywood cut
to size I started to worry that the space between the plastic and wood
bulkhead would be a potential place for water to gather and sit, especially
since the plastic bulkhead has a pin hole in it to balance the air pressure
from the forward hatch.
>
> Another reason is I thought the bulkhead would be much stronger if I
could glass the seam tape on both sides of the bulkhead. The plywood may
give a better place to mount the pump screws and washers (they would have
to contact the plastic bulkhead if not removed).
> 
> Bad idea? Good idea?
> 

Caveat:  I've never done what you're planning on doing, but am willing to
offer a few brainstorming comments.

Both approaches seem workable, but I like a third one best.

Adding the wood bulkhead to the existing plastic bulkhead could have the
negatives you mention, but the positives would be that you are adding to an
already watertight bulkhead, and so don't have to be quite as persnickety
about doing the fiberglassing *just so*.  You could also fiberglass in the
plywood bulkhead only on the sides, leaving an opening (at least a crack)
on the bottom for water to drain out, while still having a solid enough
structure as a base for your pump.  I'd be leery, though, of permanently
glassing in a piece of wood that would be exposed to so much water, as it
might eventually rot - and then you'd have to "undo" the whole assembly.

If you choose to remove the plastic bulkhead, you MUST be much more careful
about doing a *good* fiberglassing job, which may be difficult given the
location of the bulkhead, and the need for you to worm your upper body into
the kayak in a very awkward position - while holding all your fiberglassing
supplies.  The inaccessability of the bulkhead position for doing the
fiberglassing (especially from the cockpit side) may be at least a part of
the reason that the manufacturer chose to use a plastic bulkhead instead of
a glassed-in (fiberglass) bulkhead.  It is also a pretty tricky
fiberglassing job to do a seam around the perimeter of a bulkhead, as many
short pieces of seam tape would probably have to be used, given the curved
contour you're trying to seal.  Should you choose to remove the plastic
bulkhead and glass in the plywood one in the same location, it would be
important to either remove all of the adhesive used to glue in the plastic
bukhead (to provide for the most solid adhesion) - which would require
*VERY* judicious use of a sander or grinder, or would require the use of
wide enough fiberglass tape to span any adhesive residues in order to
provide for a solid and watertight joint.

A possible third option.  
Since your existing bulhead ain't broke - don't 'fix' it.
And since wood - unless *totally* sealed against moisture infiltration -
sooner or later might be prone to rot, you might want to consider an option
whereby you could install a plywood pump support that can be removed fairly
easily at a later date.  

One way to do this would be to use some sort of flanges that would hold the
plywood pump-mounting plywood piece in place. Fabricating these  would
become the trickiest part of the installation, and could be done by some
creative fiberglassing work with woven roving, or as simply as screwing
wood blocks or aluminum angle brackets through (gasp!) the hull on both
sides.  The pump-mounting plywood would then be made in a hinged fashion,
using a section of brass piano hinge, so that the plywood would unfold,
with the hinge furthest aft (oriented up-and-down), and the 'wings'
spreading out and forward into place between the existing bulkhead and the
already-installed flanges (got that?).  This allows for the use of a piece
of plywood that *exactly* fits the inside of the hull next to the existing
bulkhead.  Then -- by screwing a crosspiece across the hinge (or maybe even
mounting the pump across the hinge), the folding piece of plywood would be
'locked' in the open position between the existing bulkhead and the
flanges.  The end result would be a removeable pump mounting plate for ease
of pump servicing (and wood replacement if it eventually rots) without
compromising the integrity of the existing bulkhead. This idea would
require a bit of tweaking and fine-tuning to adapt it to your boat and
pump, but it might work. 

Regards,
Erik Sprenne

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