I haven't done it yet, but I do intend to try eventually.

One thing you need to watch out for is if you do a "wet" layup - wet out the glass then cover it with the bagging - you will draw air out of the wood. This air will need to pass through the glass and epoxy in order to be withdrawn. Chances are very good that you will get air trapped in the resin. A "better" way may be to do an infusion - bag the boat with the glass laid in place dry and draw your vacuum. Puncture the bag in a few places and hook up tubes to the punctures so the only opening out of the vacuum is through the tubes running to a bucket of epoxy. In this way the epoxy is drawn into all the cavities and presumably no air is trapped.

The difficulty is if you create an "island" completely surrounded by epoxy with no effective bleader to the vacuum pump you can still get trapped air. But with care this can be avoided.

> Can someone explain to me the vacuum bagging process. I know that the home
> built airplane guys use it a lot to get maximum strength/weight ratios out
> of a given thickness of cloth.

> As I understand it you apply the glass and epoxy in a normal way cover it
> in a “peel/ply” and/or “breather” layer, put the whole thing in a vacuum
> bag and then by evacuating the air, you get uniform pressure over the
> surface. My assumption is that less epoxy can be used and still get
> complete wet out and bonding to the surface.

> My questions are:

> 1. how do you peel off the layers after the epoxy cures? I remember trying
> to get my hatch covers off after building the lip for flush hatches. Even
> after liberal doses of past wax the epoxy was holding on pretty good.

> 2. I have this vision of the vacuum pressure squeezing out the excess
> epoxy from your layup but where does it go. At best it would come to the
> surface to be sanded down but I don’t think that is right. If it squeezed
> into the peel/ply then I assume you would never be able to “peel” it off

> I have never heard of anyone on this board using it so I assume that it is
> either very expensive or provides only marginal strength / weight
> improvements.

> Jack