I have been learning a fair amount about vacuum bagging at work though I have not tried it on a strip boat. Most of my experience comes from laying up parts in a female mold but I have been thinking about it for my next project.

Here is what I am planning (but have not done yet)

1. I would strip the hull with a couple of extra strips at the chine to get a 1.5-2.0" flange to tape the bag to.

2. Apply vacuum tape along these extra strips and cover with masking tape so it doesn't get resin on it during the lay-up.

3. Do a seal coat prior to layup so the the pump can't suck air through any gaps in the stips.

4. Lay up the outside of the hull with glass right up to the sacrificial strips.

5. Cover with peel ply folowed by breather cloth. Peel the masking tape off the vacuum tape and seal a vacuum bag to it. You will want to put pleats in the bag at the bow and stern to let the bag fit better.

6. Apply a 30hg (I think that is 30" of mercury from our gage at work). If you have a good seal the vacuum shouldn't go below 25hg in one min when the pump is shut off. If it can't hold the vacuum then you have a leak which is a problem because the pump will be sucking air all night from the leak to the vacuum hose this will can cause dry spots and defeat the whole purpose of getting excess epoxy out of the laminate.

7. Once cured the peel ply and breather should peel right off leaving a matt surface that can be sanded. You will have to trim the extra strips back to the chine.

8. Repeat process for the inside of the hull and for the deck

What I don't know is if one seal coat on a hull will in fact "seal" off the hull. I might have to tape bag material on the inside as well to prevent leaks.

On some parts at work where the peel ply side is visable we tend skip the breather layer and put breather tape along the edge and squegee excess resin to the edges.

Attache is a picture of a deck mold I made this summer off a male plug. It looks ugly with the pleats in the bag but it gave a reasonably smooth surface on the outside. The black that you can see is breather soaking up excess epoxy. Underneath it is a smooth layer of peel ply that came right off

I will keep you updated as I experiment further.

Regards,

Jack