Laminating : A Method to the Madness

Originally we weren't going to do a Pocketship blog because there were already so many excellent ones out there. However, we have found ourselves diverging a a bit from the directions in the book and therefore find ourselves in the position of wanting to share our methods. This definitely doesn't start at the beginning (beware) but we found that we followed most of the previous instructions to the letter.

All wired together... another Pocketship in the making

 

We have some tips and tricks that we have found to be quite helpful will be sharing here in hopes of helping out future Pocketship builders.

Alrighty then... let's pick up just before lamination begins.

We wired together our Pocketship in the normal manner, snapping a few wires, fussing over alignment and generally getting poked and scraped in the process... Perhaps the only difference is that we found a strap clamp held in place with clamps on either side of the hull to really help the bow alignment and make it easier to wire. We didn't have to do any of the soaking or heating that other builders described (or maybe we were just lucky?, thoughts? Did anyone else not need to heat their bow?) Although, there was some creative use of wood blocks and screws....

We cleaned her up and then did all our tack welds. The were not beautiful. In fact some of them were quite lumpy and some really sucked.

This is the point at which our method begins to diverge from the book. The book mentions going through and doing all your fillets THEN sanding and THEN going back and doing the glass. We decided this was a bit too much work and combined it all into one step.

Not really, but there are actually several good reasons to combine filleting and glassing into one step. A note here, we didn't fillet and glass the whole boat, we went by bay by bay in between the bulkheads and finished three completely in one weekend.

Reason one - Primary Bond vs. Secondary Bond
This gets a little technical but here we go. Anywhere you have a bond between layers of epoxy/glass/resin you have one of two bonds, Primary or Seconday. A primary bond is a wet bond, this is when you laminate one piece of glass on top of another in sequence without waiting for the first to dry. This allows the resin/epoxy in the layers to crosslink together during cure for a tighter chemically bond. This also allows fibers to be compacted with fewer air voids. This is why you go back and put that second and third coat of epoxy down on your laminate before it is completely cured... a better bond.
A Secondary bond is anywhere your are providing a mechanical tooth for the resin to bond to. This is why you sand all your epoxy surfaces before applying a new layer. This creates a tiny rough surface that allows your epoxy to bite into a rough surface when it cures. Think of it kind of like Velcro. Velcro won't stick to your glass table but it will stick to your sweater because your sweater is rough.
If you don't have either a Primary or a Secondary bond your really won't have much of a bond as the epoxy won't adhere very well (especially over the long tern)

Anywhere possible it is much preferable to have a Primary bond rather than a Secondary bond. However, that being said, the instructions in the book are perfectly adequate and you won't be compromising anything by following them.



Reason two - Too Much work
Neither of us is a big fan of sanding. If we can safely eliminate a sanding step it makes us happy.

On a side note. We built a little jig to hold the bow in position and allow us to take all the wires out without worrying about popping it wide open. It's two pieces of plywood screwed in a V shape to fit the shape of the hull. On the inside it has been screwed through the hull to the V. This allows it to hold its shape even if the tack welds were to fail. There are two Vs held apart by a piece of plywood. The whole contraption is held up by a stick to help it keep from sagging.

Laminating that first bay is a huge chore.

So here's how we eliminated a sanding step.

Step One - We cut out our filleting spatulas.... basically replicating what's in the book as far as shapes and sizes go. These worked quite nicely actually. We did a dry pass over our very ugly tack welds and marked any high spots to sand/chisel down. We wanted them to be below the level of the fillet after applying the putty.
Sanding and chiseling these was a bit of a chore but definitely worth it.

Step TWO - The book missed mentioning sanding the tack welds which seemed a bit remiss. Maybe our tack welds were much larger that those in the book (hard to see in the pictures). We sanded our tack welds to provide that ever important secondary bond.

Step THREE - APPLY FILLETS!!! As usual... only do one bay at a time, no tape, be neat, scrape away any rough stuff on the edges.

Note the fancy filleting spatulas

The first bay all filleted up awaiting glass.

Step FOUR - Allow the fillets to B stage. What is B staging you say? Epoxy goes from a liquid to a solid (of course) and in the course of curing it will hit what's known as a B Stage. For some epoxies, such as those used in pre-pregs this stage can be held indefinitely as long as the epoxies are kept below a certain temperature (usually they are vacuumed and autoclaved to cure). For a regular epoxy such as the MAS the B stage is a short period where the epoxy is tacky but not wet, and for putties (such as the fillets) this is where it feels kind of like a soft taffy or cookie dough. This is a short time period (maybe a half hour tops, unless its really cold) so if you aren't comfortable working fast its best to just let it keep curing and come back and sand later.

Step FIVE - Smooth those Fillets. White vinegar is surprisingly effective at removing epoxy so we used it to smooth down the rough spots on our tacky fillets. We just smoothed down some of the lumpy edges and spots where our filleting spatulas couldn't quite reach. It turns the epoxy temporarily white, but as soon as it evaporates its fine.

Step SIX - Apply glass. We weren't having much luck with applying our glass dry and then pouring the epoxy over it and squegeeing it, especially in the corners so we ended up wetting out the entire surface to be glassed and then laying the glass into it. Technically this is the correct way to laminate glass. It's always better to saturate a piece of glass from the bottom up (helps prevent dry spots) but with 6 oz. cloth it almost doesn't matter because it is so thin.

Filleted and glassed all in one day... you can see some of our taped seams.

Step SEVEN - Apply epoxy, that second coat of resin.

Filling in the weave.

On another note, we decided to tape every seam with the 6oz. cloth sent with the kit. We wanted to add some extra strength.

All done.... One bay at a time completely glassed and waiting for sanding and paint.

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