Anyway, the bulkheads are now complete. I made them out of 12mm Corecell foam with single skins of 12oz BD (0/90) fiberglass on the transom, center and bow bulkheads and double skins on both the forward and aft beam bulkheads.
I did the bagging on a waxed sheet of 3/4" Melamine, which has a beautifully finished surface. The laminate schedule for each bulkhead was (from Melamine up) peel ply, skin (or two) of fiberglass, perforated Corecell (with holes 3 to 4 inches apart), skin (or two) of fiberglass, peel ply, release material (with holes 3 to 4 inches apart), bleeder/breather material and the vacuum bag plastic itself. I would recommend a vacuum pressure between 15 to 20 in Hg for these flat panels.
Some suggestions for other builders:
- Make sure none of the material (other than the first layer of peel ply) comes in contact with the waxed surface as contamination will certainly cause delamination.
- Wet out the bottom skin(s) of fiberglass on top of the foam (which is resting on the peel ply) and then flip them over onto the peel ply on the table. Then put the top skin(s) on the foam and wet them out. It is quite helpful to coat the foam with resin prior to applying the fiberglass.
- Cut the bulkheads to shape _after_ laminating them. It is a lot more work to deal with trimming excess fiberglass from pre-cut bulkheads than to just do the initial cut from a flat laminated panel. In short: glass and bag rectangular panels, then cut to shape with the full size patterns. The aft beam bulkhead is particularly nasty if it is pre-cut.
- Happy bagging!