Lots of questions from a newbie!

Obx, you will find if you do some reading that there are two kinds of bonds you can make with epoxy. One is chemical and the other is mechanical. The mechanical bond is achieved by sanding between cured coats.
The chemical bond will occur whenever a coat or layer is added before the underlying epoxy has hardened up (when you can still dig a fingernail in).
Hardeners used with epoxy come in a few different sensitivities. Because of this, you can extend cure time long enough to be able to recoat or add another glass layer while the preceding coat or layer is still uncured. This creates a chemical bond, and therefore no sanding is needed.
If minor sanding is needed anyway, the uncured epoxy is still rubbery and the sanding is very easy. Usually, if you work neatly, such sanding is minimal, maybe removing a bug or two, or chase a few small imperfections.
Also, in this case, you would be adding a light single layer of glass, so the weight you're adding will be only slight. Maybe $1500.00 worth of epoxy and glass would double your boat's weight, but a bit over $200.00 will probably do the whole job.
The Snark is probably about the most economical new boat made. If the manufacturer had spent the labor to glass the boat it could never sell for such a low price. By glassing the boat, you will learn a hell of a lot about epoxy and glassing that will stand you in good stead later, on bigger projects.
And you're not breaking the bank for that cheap education.
I say go for it.

 

Of course others will continue to tell you to go ahead, it isn't their time or money involved. However there is ego involved, so beware.

Do yourself a big favor. Go buy a $2.99 EPS cooler and glass that inside and out. Then fair it and paint it to the standard you want to achieve with the boat.

There are red herrings being floated here about bonding. I highly doubt you are going to do your glasswork, then your fairing, then paint all while the previous coat isn't yet cured. That means you are going to sand between each step, completely sand every inch of the surface. I doubt you will be able to fair the hull the first time without at least two applications of a skimcoat.

 

ok thanks.... I did know to sand between coats. I want to achieve a really slick bottom. Prob around 1600 grit. Do you have to have a spary to get a the paint right?

 

Anything above 600 is a waste of elbow grease and time. Your paint job will probably take care of any further roughness. A few coats of wax will go a long way in getting it ultimately smooth.

Steve

 

You are welcome to sand the entire boat between coats, if that is what you feel comfortable with. In any case, there's always some sanding at overlaps, etc..
You will no doubt buy a book that covers all of these issues. Instant boatbuilding books by Harold "Dynamite" Payson should suffice for a lot of epoxy/glass lore and handy tricks of the trade.
You will find, if you continue with boatbuilding, that it's best to fair before glassing so that a minimum of softer compound lies outside of the glass (so that the surface hardness is consistant when you sand--- fairing compounds tend to get removed faster than glass/epoxy, and so might dish in during the sanding process) and also because fairing compounds are low in abrasion resisance. Only overlaps need be faired in.
Glassing, if done correctly, is very similar to painting in that it is very consistant in thickness, and once the weave is filled by the necessary subsequent coats, the surface is nearly as smooth as if it had been painted. Regarding your mentioning 1600 grit paper, it makes no sense. A correctly painted hull might first be painted with a high build primer, which would be wet sanded with grits up to 320, same with all topcoats up to the last (two or three coats), but that final coat should be glossy and need no sanding at all.
Paul's suggestion to glass a picnic cooler was a good one. Even better, glass a kiddie swim board which is a bit sturdier and can still be used afterwards.

 

Mates we are talking about a tiny little boat here, are we? So, if the inner or outer skin is made more or less in one go and the hardener is´nt set too fast, it should be possible to get the glassing and say two additional resin coatings done in one day. Then there is no need to sand / fair between the EP layers.

 

yeah it is a very small boat 11 foot length and 3 foot beam. Think I will try the cooler. Thanks for the suggestion. It may be bout a month or so before I can get to this project. I am moving soon and then going on vacation. I think I am going to sail her for the summer and then glass her over the winter when I have time to be patient. Thanks for all the help. I hope I am not making you guys crazy with all the questions.

 

So thats roughly 3,3m² surface outside and say 4m² inside = 8m² max. surface to be covered. Assuming a 240gsm cloth = about 500gsm = total weight of the glassing layer = 4kg glass and resin. A gap filling coat is about 140gsm having two of them is 280, say 300gsm = 2,4 kg (one should do, using filler)
Thats 4,5 kg resin hardener mix and 2 kg glass
A filler is about 150gsm dry matter, thats one pot (if used outside only), usually filler is sanded down to about 50% or below, so you add just 250gr to the weight of boat. Now two coats of paint @ 150 gsm liquid = 2,5 kg, that reduces to about 1kg dry matter after curing and sanding.
Done in a proper way thats a bit overkill on such a boat, but adds about 5,5 to 6kg to the weight.

Regards
Richard
>>>gsm<<< = gram square meter

 

Seems like a lot of work

Yes you can glass it. Use a light weight cloth and roll the glass on. Make sure you have disposable everything. Use vinegar in lieu of acetone to clean your hands. Once you get the mix right you can move pretty quickly. Use wax paper to round out corners. Remove it when the glass starts setting. It will give you a much smoother finish than sanding for hours. I guarantee the time and material will be worth more than the boat.