Sunday, April 13, 2008

Starting lamination of main hull bulkheads - a problem with using plastic over the peel ply

It has been hard to find time lately to work on boat parts. Same old story, too much time at the day job. That said, the little boat building demon in me will not let things stop totally. I started a test part ( the small middle forward bunk bulkhead) with the plan to do one side at a time going for a hand lay up, using peel ply and the plastic so that I could squeegee the air and excess resin out. To my surprise I found out that using the plastic on one side of a foam piece will not create the vacuum that I have seen elsewhere on the outer float hulls. After I would compress the foam, air would reappear underneath the plastic sheet. I can only deduce that the Divinycell foam that I am using is not totally closed cell in construction. I will be running out of Divinycell sheets at some point fairly soon. I think that I will make the main hull out of Corecell, especially if the foam turns out to properly closed, in other words, one side of the foam air isolated from the other.

So, for the moment I am just using peel ply as I can knock them off pretty quickly, laminating one side at a time. The epoxy weight to cloth weight ratio is alittle over 1 on the first part (ie epoxy weight/cloth weight) but I can live with that. I could go back to vacuum bagging the flat parts but it will require a setup of a larger table and I can't seem to find the time.

There are other techniques I can try. No doubt by the time I have all the bulkheads done it will be quite optimized. I can see why that after building the first boat some people just have to build another. All these skills that have been mastered and optimized for ones own personality, just have to be put to some use!


Tor Rabe said...

Hi Grant!

I use the Divinycell H60 as an air tight "mould" when vacuum infusing. The older formula that I used in the beginning has however a bit larger closed cells and the screws used to hold the foam was more likely to puncture cells far enough to create small leaks. Anyway, I do not think the Divinycell is the reason for your problems.

GK said...

Tor, your probably right, at least I would like to think so.