Sunday, November 23, 2008

Glassing the Inner Skin

Oh boy, this was a fun job. Seriously!

On Monday, we completed a hand lamination of the inner skin, complete with reinforcements around the beam bulkheads and the bagged the entire half of the ama. I am quite pleased with the result and feel like having a party to celebrate. Mai tais anyone?

For all time intensive laminations, I am using Proset 125/229 epoxy, which is produced by Gougeon Brothers (makers of WEST epoxy). This resin/hardener combination has a very low viscosity (450 cps mixed) and makes wetting out the fiberglass easier. The greatest part about this epoxy is its incredibly long pot life (77 min at 72F) and working time (thin film) of 2-3 hours. It might sound strange, but I also find the smell of the 125 resin quite pleasant.

Anyway, in order to vacuum bag the entire hull half, I needed to create a flange to bed the mastic sealant tape and run the excess fiberglass, peel ply, release and breather onto. I left the keel foam proud about 2" above the keel batten and pre-glassed one layer of the deck flange 2" wider than need be before the bagging operation. In addition, I added excess foam at the bow and transom to define the bagging flange there. The entire outline for the mastic sealing tape was defined by a putty mixture to seal the foam and deck flange, in addition to providing a solid bonding surface for the mastic tape.

I cut all the dry fabric (fiberglass, peel ply, release material and breather) to shape before laminating and I left the fiberglass on the foam to be wet out. I did not pre-wet the foam, or, in Ian's building terms, I used the "Dry Method" to laminate the fiberglass. This worked out well - the epoxy has low enough viscosity to wet out the glass and the foam (I checked by lifting up the wet fiberglass) and the vacuum bag pushes the glass tight to the foam.

The results of vacuum bagging are terrific. In my opinion, there is just no way to attain vacuum bagging results with an open or hand lamination process.


Fram said...

For making panels and bulkheads resin infusion is so much easier than wet vacuum bagging. Please try it and you will never look back.

Keep up the good work.


Grant said...

I too have always found the smell of epoxy resin - not unpleasant :)

Pete144 said...

You know I'm always willing to drink, even if it is Mai Tai's :)

Mike Paulding said...


Thanks for the suggestion. I have wanted to dabble with infusion for quite some time. I actually purchased the required materials for the 4-man surf canoe I built, but then I chickened out and vacuum bagged everything (with hand lamination).

I'm waiting for a side project where I can try infusion without worrying about a failed part. I'll let you know when I become a convert :)