: This past spring I built a sized down version (9 1/2') of a Wee Lassie. Using
: 6 oz cloth, it ended up weighing about 18 lbs. Now I want to try to build
: a Sairy Gamp, and would like to keep the weight as low as possible. I was
: wondering if it is absolutely necessary to fiberglass both inside and out.
: I think I can lower the weight by about 3 lbs by using 4 oz cloth, but I
: would like to get it lower yet. Would it be a very bad idea to fiberglass
: the outside only, while coating the inside with 1 coat of Epoxy to seal
: it?

the original Rushton designs for those boats were built quite a while ago. PEr haps some historian can get a moe accurate answer, but I believe these things were first built in the early 1900's -- long before epoxy resin or fiberglass cloth hit the scene.

1/4 inch strips nailed to internal ribs were standard in those days, I believe.

If you go without any glss cloth, stick to 1/4 inch, but if you go with cloth, consider thinner strips. You can go down to 1/8th inch if you use 3 layers of 2 ounce cloth.

You might consider going to very lightweight cloth -- say 1 ounce -- to start with and see if it provides sufficient strength. If not, you fix the cracks and put on a couple more layers. Multiple layers of light weight cloth build up strength equal to ( and some have argued -- better than --) the equivalent weight in a single thickness of fabric. so 4 layers of 1 ounce sloth should e as good as 1 layer of 4 ounce. By using the thinner cloth you can put just the thickness you want where you need it. Thin cloth has nearly no weave showing, so "filling the weave" is done on the second (light) coat), if you even need it at all. A coat of varnish might even fill the weave for you.

I'd use epoxy resin, slightly thickened, for gluing the strips so there would be no concerns about the glue softening with immersion. Or, I'd use a 2 part waterproof glue (DAP makes it) which is a darker color (pretty glue lines) and dries a bit harder, but is every bit as strong.

These boats don't have a lot of strips, so you'll just mix many small batches of resin or glue. It is just a bit inconvenient, but it will hardly slow down your construction.

Defender has the lightweight cloth at pretty reasonable prices. check www.defenderus.com for their online catalog or to order a printed version.

One thing about using very thin glass cloth: If you apply it with a squeegee it guarantees an even thickness of resin. If the glass cloth is wetted out,then it has resin in it. If you pass the squeegee over the cloth you scrape off any excess that is above the cloth. Except for those areas of runs and drips, the final result is a layer of resin that is just as thin as the fabric you use. The fabric serves as a kind of depth gauge for the resin coating.

Of course you will put on a very scant first coat to seal the wood pores, applying as little as possible.

Defender ( and other places) also have a "scrim" material which is similar in that it is light weight cloth made glass fibers, but this is not a woven material. It will also serve as a "depth" gauge for your resin, but it is probably not as strong as the cloth.

If you decide to try cutting the weight to the maximum, just put cloth on the inside. It is needed there to replace the ribs that used to be used. the outside fabric is just there for waterproofing and abrasion resistance.

Oh, and skip the 2nd coat of varnish. One will give you the UV protection for this year. Next year you can revarnish it.

Hope this helps.

PGJ