Glen-L.com

True,however, that part of the stem(end grain) is held captive by the two pieces of solid wood frame,so the screws can't spread and split the end grain of the plywood stem

_________________
Boat building can best be defined as an endless series of
tragedies obscured by the occasional miracle, followed by a good bottle of beer.

Don't Dream Your Life, Live Your Dream

This was my reasoning for mention of using solid oak for the stem. If you are leary of using plywood for this reason. Pirate is correct in his statement. I wound up using oak for the stem n the Stiletto because I didn't have enough material left of my 4X8 plywood piece to make both laminations for the stem. It was more economical to use the 1X12 oak than to purchase another sheet of plywood.. Besides, it is definitely stronger.

Okay, that makes sense. I'm planning to build the stem from laminated parts of 3/4" plywood.

That brings me around to the topic of adhesives, encapsulating, and fiberglassing. So, I've got some new questions:

1. Once I encapsulate the frame members with epoxy, do I then use that same epoxy to glue the frame members together?

2. I've read that epoxy (once cured into the wood) needs to be protected from light... most easily by paint. If this is the case, what is used to encapsulate the surfaces of "bright-finished" wood (like the natural-wood finishes on many Zips and Squirts)?

3. Is natural/bright-finished decking encapsulated? Or only covered with multiple layers of varnish?

4. What is the difference between fiberglass resin and epoxy?

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-Michael

my boatbuilding blog:
http://barnaclemikeboats.blogspot.com/

1. You can use the same epoxy resin for encapsulating and gluing. Most glued joints may need some gap filling, so resin needs to be thickened so it won't run off and leave the joint glue starved. I prefer to use a prethickened epoxy like System Three Gel Magic or Glen L's Poxy Grip. Poxy Shield or System Three resins are used for encapsulation and wetting out the fiberglass cloth.

2. Most paints and varnishes have UV blockers and should be used over resin that is exposed to sunlight.

3. You can do it either way. Below water line areas should be epoxy encapsulated with fiberglass cloth to protect these areas from abrasion. Upper sides and decks can also be epoxy coated and fiberglassed. Six ounce or lighter weight glass cloth becomes virtually invisible when properly wetted out with resin.

4. Epoxy is a resin. In the adhesive form it has thickeners. There is another resin used for fiberglassing called Polyesther resin. It is generally not compatable with epoxy.

Roberta

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Roberta
Built Zip "Oliver IV" and Super Spartan "Jimmy 70"

I have been using Aeromarine epoxy resin. The cost is lower than most others. They have thickeners you can use. I have just been getting there pecan flour. It also is good for screw holes, although it is a little dark. I try to be careful to space the screws evenly so the pattern is consistent. Of course, you can also purchase a plug cutter that will fit any drill press to make wooden plugs.

Thank you so much, Roberta and PamelaLynne...

Do I also use this same epoxy to laminate the two plywood pieces for the stem? And if so, does that automatically encapsulate the "interior" surfaces of the lamination?

-Michael

_________________
-Michael

my boatbuilding blog:
http://barnaclemikeboats.blogspot.com/

It's good for any application. You only need to thicken it a little to get the consisteny you want.

What is the main purpose of the thickener when you add it to epoxy for gluing / laminating? Is it simply to prevent the liquid from running to much, or is there another reason?

_________________
-Michael

my boatbuilding blog:
http://barnaclemikeboats.blogspot.com/

For laminating wood on a fairly flat surface, you normally wouldn't need thickeners. You should "prime" the two surfaces with epoxy and recoat just before mating the parts together to prevent too much epoxy from soaking into the wood and starving the bond. Thickeners are used to keep the epoxy from settling out on more vertical joint surfaces and to help in gap filling of joints. I prefer to use straight resins for laminating, encapsulating, and wetting out glass cloth. I use a product like Glen Ls Poxygrip or System Three Gel Magic for glueing joints and areas where the epoxy needs to be thick and, due to it's position, could drain away.

Roberta

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Roberta
Built Zip "Oliver IV" and Super Spartan "Jimmy 70"

Basically anytime you're gluing something with epoxy and there's a risk there might be cavities, where air can get in, it's good to thicken the epoxy. The handy thing about doing that is that you don't necessarily need to coat the surfaces that you're bonding first with epoxy and again when gluing, because the thickened epoxy will fill in the contact area fully.

The Squirt's a fun boat to build. Hope you have a blast building it.

Richard

By priming the mating surfaces with 1 coat each of epoxy, then adding an additional coat for gluing / laminating, does that suffice for encapsulation of the mating surfaces?

I am assuming that the mating surfaces should be encapsulated before being laminated together. However, at some point I'd be mating epoxy-to-epoxy instead of wood-to-wood wouldn't I?

_________________
-Michael

my boatbuilding blog:
http://barnaclemikeboats.blogspot.com/

Yes, that will encapsulate the mating surfaces. I too am building a squirt and we seem to be neck and neck as far as progress goes.
The up side of priming and bonding in the same day is you will not need to clean and sand the mating members (no blush).
I have been mixing batches of epoxy without any filler and priming the pieces to be glued then I add my filler (colloidal silica) to the remaining resin for glue up. From what I have read colloidal silica is great at preventing sag so when you get squeeze out it is more like peanut butter and less like jelly. It makes clean up after clamping a breeze.
I am no pro by any means but I have spent years researching epoxy usage preparing for the day I would finally use it in a build.

When you're encapsulating wood or ply with epoxy, you're essentially making it water proof. You're not said to be "encapsulating" when you're bonding two pieces of wood or ply together, but yes, that enclosed and bonded area is also waterproof.

There are two schools on the encapsulation issue: those who prefer to do it after all the pieces have been glued together with epoxy; and those who do it before they begin bonding the pieces together - coating each cut piece separately before the assembly process.

In most cases, I prefer to encapsulate all wood and ply first and then deal with any sections made bare from from sanding or planning during the fairing process.

I believe Roberta advised encapsulating the area that you'll be gluing first and then applying the glue/epoxy to both sides when you are ready to bond the two pieces of wood or ply together.

I proposed that you don't have make it a two step process if you add a thickener to your epoxy. By making the epoxy more "goopy" (a little thicker than even say standard white wood glue), you'll likely fill the space between the two surfaces being bonded.

Either way, the bond will be stronger than the wood, but I would recommend that all external and exposed surfaces be covered (encapsulated) in epoxy after you've assembled all the parts to your hull. There are two schools on that too, but that might be for another post.

Cheers,

Richard

Actually I was describing how I use resin for laminating. The primer I described is just a coat of resin on the two mating surfaces to be laminated. A short period of time is allowed for resin to soak into porous materials, then another coat is added to areas that appear to have absorbed resin and may be starved. The coats are never allowed to cure before the pieces are mated.

I also advocate encapsulation after the major parts are assembled.

I would advise getting Glen L's books on building with plywood and books about fiberglassing and working with epoxy resins. Another good source is the System Three Published Liturature:

http://www.systemthree.com/reslibrary/m ... rature.asp

Roberta

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Roberta
Built Zip "Oliver IV" and Super Spartan "Jimmy 70"

Thank you all for your insight, and thank you Roberta for the link. I downloaded System 3's pdf & am looking forward to reading it.

I have a question about assembling frame #2 of the Squirt... The bottom members of the frame butt up against either side of the aft section of the stem. The bottom members are connected by a single backing piece that also bolts into the aft surface of the stem. The top of the frame is connected by a deck beam that laps on the forward side of the frame. I have not yet built the stem.

So, here's the question: Should I assemble the frame now, and then fit the stem to it later? Or, should I wait until the stem and the building form are made, and then assemble the frame and stem together? My main concern is whether or not I'll have enough latitude to adjust & align the frame as needed once everything goes to the building form.

For reference, here's a photo of all the frame members (minus gussets) aligned together. (You can see the "notch" where the aft section of the stem fits to the frame at the bottom of the photo).

_________________
-Michael

my boatbuilding blog:
http://barnaclemikeboats.blogspot.com/