Saturday, August 25, 2007

Aborting vacuum infusion of float exterior

So I kept on laying all the layers required for a vacuum infusion. Here is the Peel-ply:

Then the release film and the RDM. I learned from the latest float half that a double layer of my RDM halves the migration time of the epoxy, as does three layers. Here is two layers of RDM and the distribution tubing:

Then the whole float was sealed in the vacuum bag, leaving a 10 mm hole in the deck to connect the float inside with the atmospheric pressure.

Then I started the vacuum pump. I did not get an appropriate vacuum and I did not manage to find the leak. I figured that a larger amount of air through the system would reveal the leak. And it did. I connected an industrial vacuum cleaner parallel to my vacuum pump. Less than a minute later I observed that the float shape was changing into a less appreciative form. I rushed to the power chord and observed the float as it reversed to it's original shape.
The 10 mm hole was no longer able to provide the amount of air necessary to maintain balance of air pressure, hence the leak was in the float wall. I don't know where this (these) leak(s) is/are, but the float to deck join is one candidate, as is the possibility of my 6mm Raptor composite staples have penetrated the inner skin in the keel area (where the foam is sanded down in order to create the correct rounded shape). Here is a picture of the vacuum before the threatening collapse:

I had to sit back for a while, making a new strategy, until the final decision on how to proceed was made. I must say, I really do appreciate the quality the vacuum infusion method provides. On the other hand, I really do love sailing and I ended up finally following the designer's advice and I decided to lay the outer skin manually, praying that I would be more lucky than Jay regarding bubble trouble.
I started to remove layer by layer and preparing for the hand laminating method:


Tom McCaw said...

You could just do one side at a time.


Tor Rabe said...

Well, I think the leak would not go away no matter how I place the bag. The problem is probably, as Roger Bonnot also pointed out, that 10 mm foam is difficult to make airtight, and on the floats it is sanded down to nothing some places (along keel).