If n' When II -- Hatches

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Because I was going to use Valclav's hatch seal concept and Rob Mack's method of rare earth magnets for hatch retention, I was going to lose an inch all the way around inside the hatch. After measuring hatches on a few boats, I settled on a size that wasn't much bigger than the designer suggested.

I waited a day to get my nerve up before cutting the hatches. It's kind of scary cutting into the deck that you've just spent weeks constructing! The sabre saw with a fine toothed Bosch blade did a very clean job of cutting the hatches. I think the secret is a very sharp blade.

The deck starts to look a little "holey" with the hatches cut out.

Magnets were fitted to the hatch covers using a router with a 1/2" straight sided bit to cut the 1/8" deep recesses for the magnets. The magnets were postioned 7/16" from the hatch cover edge to leave room for the foam gasket to seal along the edge of the hatch cover. The magnets were seated in epoxy and then covered with epoxy to keep them in place and keep them from rusting. I ended up with magnets spaced evenly around the cover - the distance varied between 4.5 inches on the smallest cover (with 6 pairs of magnets) to 5.4 inches on the largest cover with 9 pair of magnets. Once the epoxy cured on the covers, the covers were taped back in place in the deck.

The covers and area surrounding them was covered by plastic to serve as a mold release once the retention rings were created. The other half of each pair of magnets jumped in place, and a thin gasket was positioned appropriately. The blue tape is just to give me a clue where the edge of the structure should be once it is completed.

The sorcerer's potions. Epoxy and hardener, fumed silica for light weight filler/stiffener, and the trusty, nearly empty toner cartridge hiding in the back for black tinting agent.

After applying the black epoxy paste as a fillet over the foam gasket and magnets, I laid up several layers of glass and carbon fiber scraps, topping it off with one large piece of material to help get it smooth.

After the gasket molding cured, it was trimmed with the sabre saw and attached to the deck with thickened epoxy.

Once the hatch gasket channels were in place, I hot glued bias cut cloth in the hull along the shear seam, and put the two halves of the boat together for the last time. (Technically, this is correct. The day before the boat had been together and I tried the "roll the tape, soak it, and then unroll it in place" technique. This was not successful for me, and the cleanup was time consuming...) With the tape in place, and the boat on edge, it was fairly simple to saturate this joint with epoxy.

I tried a couple "special tools" to assist with wetting out the seam tape. The fancy corner roller worked reasonably well, but was too big to fit clear to the ends. 'Sides that, I'd only purchased one, not thinking about the overnight epoxy curing cycle prior to flipping the boat for the other seam. A triangle cut from a bilge sponge and hot glued to a stick worked quite well when assisted by gravity for the ends of the boat. The center section was done with a 2" disposable bristle brush.