Newbie fiberglassing question

Builder's Forum
1

I am about to fiberglass my Skerry. Some things are unclear to me, after reading the manual and some of the exchanges here:

1) When I drape the fiberglass over the hull, the glass obviously won't lie completely flat. How do I ensure smooth coverage without folds, bubbles, cuts, etc?

2) The manual says "Carefully stretch and smooth the cloth to cover the bottom and the #1 planks." How do I hold then hold the cloth in place. My only idea so far is masking tape.

2) I'd appreciate any hints on how to ensure a clean lap joint at the end of the first panel. I can easily imagine the cutting of the glass along the seam being uneven, and tearing the glass.

2

"1) When I drape the fiberglass over the hull, the glass obviously won't lie completely flat. How do I ensure smooth coverage without folds, bubbles, cuts, etc?"

You worked with fiberglass cloth before?

If your hull is upside-down and you've done a nice, thorough job of sanding then de-dusting the surface so everything's niocely smooth with no little thingys sticking up to catch the 'glass fibers, it'll lie nice and flat. You can even use a stiffish, wide brush (like a wallpaper brush but be careful!) to 'sweep' the glass cloth smooth, working out any ripples or bubbles as you go.

"2) The manual says "Carefully stretch and smooth the cloth to cover the bottom and the #1 planks." How do I hold then hold the cloth in place. My only idea so far is masking tape."

Forget anything with adhesive. It'll be a PITA to get off the cloth w/o pulling fibers with, and may contaminate your surface. Some folks use pushpins but I find if the plywood's surface has been nicelt sanded there's enough 'tooth' left in its texture to hold the cloth in position.

"2) I'd appreciate any hints on how to ensure a clean lap joint at the end of the first panel. I can easily imagine the cutting of the glass along the seam being uneven, and tearing the glass."

This takes experience. And a careful approach to timing the application of the lapping layer over what's been placed earlier.

Unless you're really skilled I wouldn't even think about doing this in a continuous operation. Better to get the first layer on smoothly, then time the second layer so that the first has become 'green-hard' to the point you can dent it with a fingernail but it's not really sticky.

You might even wait until your first layer's cured hard enough that you can feather the cloth edge where the lapping layer will overlap it.

Either way you're doing the lapping layer after the underlayer's become hard enough to stay in place but not so hard that the next epoxy applied won't bond well. Then you can lay down the overlapping layer of cloth & epoxy without undue angst.

Wait until it's cured 'green' then carefully use a box cutter / utility knife to trim what might be a ragged edge as needed. If the cloth & epoxy underneath's cured well you don't risk cutting into the cloth much if at all, as long as you use a light tough on the blade. Like I said it takes experience, which takes time and practice to acquire.

 

  

3

You worked with fiberglass cloth before?

No, I am a true newbie.

The end of your message has me quite confused, as the manual does not talk about a lapping layer. (And the video about glassing, on the CLC website, doesn't mention this either.)

Unless you're really skilled I wouldn't even think about doing this in a continuous operation. Better to get the first layer on smoothly, then time the second layer so that the first has become 'green-hard' to the point you can dent it with a fingernail but it's not really sticky.

What is the "this" that should not be done in a continuous operation -- it sounds like you are talking about a second coat of epoxy.

You might even wait until your first layer's cured hard enough that you can feather the cloth edge where the lapping layer will overlap it.

Feather?

Either way you're doing the lapping layer after the underlayer's become hard enough to stay in place but not so hard that the next epoxy applied won't bond well. Then you can lay down the overlapping layer of cloth & epoxy without undue angst.

But this sounds like you are talking about a second layer of fiberglass.

Wait until it's cured 'green' then carefully use a box cutter / utility knife to trim what might be a ragged edge as needed. If the cloth & epoxy underneath's cured well you don't risk cutting into the cloth much if at all, as long as you use a light tough on the blade. Like I said it takes experience, which takes time and practice to acquire.

Are you saying that the sequence is:

- Glass
- Epoxy
- Feather? (Still don't know what that is)
- Glass (lapping layer?)
- Epoxy
- Trim both (?) layers of fiberglass

I appreciate your response, and I'm sorry to be so dense, but I just can't match up what you wrote to anything else I've read or watched.

4

That point you'd tagged with a second 2) (meant rather to be 3) is what I was addressing when I spoke of a lap joint. You wrote: "I'd appreciate any hints on how to ensure a clean lap joint at the end of the first panel."

So I was thinking maybe the panel you were referencing was the first length of fiberglass when what you have isn't long enough to cover the entire hull's length?

If instead you'd meant panel in the sense of pieces making up the hull itself, I have to wonder (not having built a Skerry myself) if a lap joint (one layer of epoxy-saturated fiberglass cloth overlapping another underneath) is even necessary? The only overlaps I'm familiar with would be where deck-covering cloth is run down over the upper panel at the sides of a hull, or perhaps where cloth wraps around the corners at the transom or the bow.

Here's hoping others more familiar with the Skerry and how to build one will chime in on this.

As for feathering? That's an operation whereby the thickness at the raw edge of epoxy-saturated fiberglass is reduced in thickness so as to permit subsequent layers to leave as little telltale of the edge underneath from 'telegraphing' at the newest surface. Sanding, scraping, using a file... all have their place in this kind of operation, depending on the skill of the builder and the care in which the edge was left to cure before they took a break.

5

https://www.clcboats.com/shoptips/epoxy_and_fiberglass/fiberglassing.html   

https://www.clcboats.com/shoptips/epoxy_and_fiberglass/epoxy_bubbles.html

https://www.clcboats.com/shoptips/stitch_glue/cabinet_scrapers.html

Targeting repairs to fiberglass but the techniques discussed have a place in our kind of projects:

https://www.epoxyworks.com/index.php/common-errors-in-fiberglass-repair/

Specific to the feathering operation:

http://buildersforum.bearmountainboats.com/viewtopic.php?t=4887

There's all kinds of stuff out there to help you pick up useful techniques. Some might be behind a paywall but if you're diligent you can find a great deal out there for free viewing.

6

   Check out the shop tips and videos in this site.  They are pretty good at showing the 'glassing.  Accept that you will bugger something up.  I've got 3 of their kits done now, including a skerry and I had to fudge something on every one.  

On the skerry, I wish I had laid down masking tape at the plank edges where the 'glass was supposed to end to make it easier to trim and avoid some of the drips.  Other than that, yeah, the smoother your sanding job the less picking and dragging of the cloth will happen.  I wore gloves when laying it out, partly because my hands and fingers were rough and tended to pick the fabric. The idea of using a clean dry paint brush to smooth it can work well.  It should sit pretty well with just a bit of brushing and pulling.  The weave is fairly loose and the fabric can be shifted to cope with moderate curves

I think the "lap joint" you are talking about is on the bow and stern, right?  In my case, I took my shears and cut a slit in the cloth up the line of both ends so I could tuck one side under the other and drape them around the ends of the boat.  

I started pouring the epoxy in a line down the midline and squeegeed it out from the center.  On the ends, if you got the slit or "dart" in the cloth right, you can smooth one side onto the hull w/ the epoxy and it will hold well enough to then drape the other over and finish expoxying.  A chip brush can be useful to dab or tap w/ the brush ends to work the resin in and work out air bubbles.  On the ends, I wound up using my fingers (gloved) to work the edges together.  There will be some frays and occasional loose threads, but they can be cut away or sanded down.  Before it is really hard set, trim the edges to the tape, and pull the tape to carry away the curing drips and frazzles.

Fiberglassing the inside is trickier, I think.  It's got curves that make the cloth want to pucker and if you get too much resin in there, it can float the cloth up off the wood.  On the inside, go easy on the resin and use just barely enough.  It will want to puddle if you don't.