Hi Ed, Most commercial boats with foam bulkheads use 3" thick minicell foam, generally glued in with 3M 5200 adhesive. It's a good system, but expensive, and reported to leak sometimes. (Don't know that personally)

You could easily strip a panel and just use the corresponding form to give you an exact shape to fit into the boat. The only problem with rigid bulkheads is the risk of "stress-risers". There is an explanation in Nick's book--basically, if you hit the hull on a rock near the bulkhead, the boat is less flexible in that area, and rather than flexing, it could shear or break near the bulkhead.

> What I have thinking about is the material to use for bulkheads. I
> remember checking out the bulkheads on a commercial boat once and was
> suprised to learn that they were soft and flexible to the touch. They
> seemed to be made of 1/2" foam, like you'd use for a sleeping bag
> pad. They were caulked around the edges that I could see. My question is
> this: Is this kind of material suitable for bulkeads? I have some dark
> blue foam that was a sleeping bag pad in another life and would gladly
> recycle it into the kayak. I also have some very rigid 2" thick
> building insulation foam that I could use. I would have to make two piece
> bulkheads with the rigid stuff to get around the footpegs or in the hatch
> opening.

Try to avoid making two-piece bulkheads if you can help it--you'll never be able to connect the two halves inside the boat as easily as making it one piece to start with. You should be able to remove your footpegs and just leave the rails in. Put the bulkhead in, angled slightly, and once you're past the footpegs, turn it into place.

Seda uses some really nice thin glass bulkheads. Imagine covering one of your forms with plastic wrap, and laying up a single layer of 10 oz. glass over the form, letting the glass drape down over the edge of the form. Peel the glass off the form, trim the edge of the glass to leave a 3/4" rim around the bulkhead. Put thickened epoxy all the way around this rim, and slip the bulkhead into place. It will seal well, allow light to enter the bulkhead area from the cockpit, and it's probably thin enough to minimize the risk of stress risers.

> I am less inclined to use a strip built panel or a piece of plywood. Both
> would be heavier and more trouble to fit than the foam and have no
> aesthetic advantage _inside_ the boat. I also do not need the additional
> rigidity in the hull since it is quite heavy and rigid enough from the two
> layers of, *ahem*, 8.9 oz. cloth on the outside of the hull.

Two layers of 8.9 oz? *heh heh* You da man! I don't think you'll be worried about too many barnacle landings, eh?

> Is the foam material suitable? Is the only purpose of bulkheads to keep
> the water that gets into the boat in the same area it entered from? What
> forces will the bulkheads be subjected to? What kind of sealant would be
> best for securing them in place?

Yep, the bulkheads keep the water in one spot. Generally, you want them to keep the water in the cockpit after a wet-exit in the cockpit, leaving the ends dry and floating. (You'll probably want backup in the ends, but that's another story). The bulkheads will probably experience compressive forces from outside, but as far as straight-on forces, only the weight of the water pushing against them. Use 3M 5200 for foam, thickened epoxy for glass or woodstrip bulkheads.

Shawn