I have started doing home experiments with vacuum bagging of epoxy/fiber.

I did two identical 6 inch squared pieces with plywood and foam core, one was done by hand only and the other vacuum bagged, see pic.
The fiber/epoxy ratio of the standard piece was 25% (including one fill coat)
The fiber/epoxy ratio of the vacuum piece was 47%

My kayak (S&G hybrid) will have foam cored hull (Divinycell H160 5mm), and strip deck, hopefully the weight of the hull will be approximately half of the weight of a 4mm Lauan 163g glass inside/outside hull.

I use a Mityvac vacuum pump, used for brakes or whatever in cars and the same bag peel-ply and breather fabric as the professionals. Good, and plenty of, sealant tape is absolutely necessary if you dont want to spend 5 hours pumping. This time I kept approx 25 inch Hg during during curing which may be a bit high (some dry fibers on the surface?)

I will try bagging the deck during christmas holidays.

I am a bit worried about deformation during curing of the hull because of the vacuum. I will have the deck-forms in place inside but any tips would be gratefully accepted.

Niklas