Try to contain your excitement as you peruse my stack of bulkheads, furniture, and other flat parts. Bulkheads are 18oz BD, except for the main hull beam bulkheads, which are carbon. Furniture is 9oz 8HS on top, 7.5oz plain weave underneath. The 8HS actually absorbs less resin than the lighter plain weave and results in a far smoother finish. I tried laminating one piece without vacuum-bagging or using peel ply just to see what it looked like and it looks awful. Fortunately it's the underside of the v-berth so I don't have to spend weeks sanding and filling. I did spend a long time trying to wash amine off the surface.

To vacuum bag both sides of a panel at once, the usual method is to laminate from the bottom up directly on a waxed bagging table.  The layers go: table, peel ply, fiberglass, foam, fiberglass, peel ply, bleeder, vacuum bag.

I had a few problems with this method.  First, it requires sealing the bag to the table on the entire perimeter.  Since my pump drew high vacuum but relatively low CFM, I had problems with leaks.  There's nothing worse than running around trying to detect and close pinhole leaks while your resin kicks.  Second, I didn't have space for a permanent large bagging table, and third, I got a lot of wrinkles in my bottom layer of laminate because you can't squeegee it directly onto the foam with this method.

Instead, I use a large piece of 2" thick Celotex foam from the building supply store. I perforate the foam core with a nailboard, coat the core with resin, then lay the glass in the resin and wet it out, just as if I were just doing a single layer laminate. Then I lay the peel ply on top, put the Celotex on top of that, and flip whole thing over, so that I'm left with the fiberglass I just wet out sandwiched between the foam core and the Celotex panel, and the "dry" side of the foam core facing up. Next I laminate the top layer of glass, add peel ply and bleeder, and slide the whole thing into a sleeve-type nylon or poly bag.  Once I draw the vacuum, I can move the bag around or even prop it against the wall while the resin cures.

The Celotex is stiff enough to keep the bag from warping the part as it contracts. For larger parts that are too big to fit on the Celotex, I laminate one side at a time but have to stack weights on the corners to keep the part flat while it cures in the bag. So the Celotex acts as a caul inside the bag.

What's the number "760" doing on the panel above?  After I cut my panels to rough shape and measure the fiberglass for a panel, I weigh the glass.  I'm trying to get 50/50 fiber to resin ratios, so I mix up approximately the same amount of resin as the weight of the glass (plus 10-15%).  Because I have a mind like a sieve, I can usually not remember how much the glass weighed by the time I get around to mixing the resin, particularly if the glass on either side of a panel is different weight, so I write the weight of the glass on the panel in a large marker to give me an idea of how much resin to mix.  It's also helpful to write the weight on the glass itself (which is why you can see a backwards "12" on the same panel) if the weights on each side are different.