saturday morning seems like a great time to think about boat building! as i start planning the super skipjack build, i'm trying to decide if i am going to glass the boat. there are lots of good posts here about the benefits, but i'm wondering about the cost. can anyone give me a ballpark as to what it cost to do a weekender, and then i'll have a rough idea about the cost my skipjack?
Take the length of the boat, multiply by .7% of the beam and this is the amount of fabric you need for the bottom. Multiply the length of the hull side by .8% of the height of the side at the bow. Multiply this by two and then add that number to your bottom figure. This is the rough estimate for a sheathing, per layer. Of course you'll have to buy fabric on a roll, which doesn't have the width to do the whole boat in one shot, so you'll do one side at a time, starting at the centerline and working around the rounded over chine or starting at the sheer and doing the sides first then the bottom. The amount of goo to wet this out depends of several factors, like cloth wight and type, resin brand, temperature, etc. As a rough guide, you'll need about a gallon for each 300 to 400 square feet of fabric, at least a gallon just for the bottom planks, and probably two more to finish the hull sides and most of the cockpit.
Some use straight epoxy to fill the weave, but this is a very costly way of doing it. I wait until the wetout coat is just barely tacky then smear a very thin fairing compound coat (thickened epoxy) over the whole hull. This uses much less epoxy and it's a whole lot easier to sand. If I expect a lot of fairing (most novices should expect this) then I'll apply a thicker layer of fairing compound, knowing full well it will be mostly sanded off in the fairing process.
Maybe some others can directly comment about how much goo and cloth they used on their builds.
When you are preping the surfaces of this boat remember you are not doing body work and a lot of the inperfections like dents and screw holes will be filled as you epoxy and glass the surfaces. I spent hours finisihng everythng like it was a prised roadster only to cover it with glass and fill. I would guess this obsession cost me ~150 hours more labor. A total waste. I most likely used 30% more goo than I needed only to sand it off and track it into her house. I am not allowed t build boats in the garage any more
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I used a  3 gallon RAKA kit and had about 1 gallon left over - I don't remember how much cloth.  Seems like the entire epoxy/cloth kit was about $250 for my weekender in 2001 - looks more like $300-400 now.  This is, of course, just a fuzzy memory made even more indistinct by years of sun exposure while sailing my weekender.
Marinepoxy from Bateau.com costs about $95 for a 1.5 gallon kit and a 3 gallon kit is about $160. Assuming Norman used 2 gallons for sheathing the hull and you plan on encapsulating the hull shell at the very least, you'll need all of 3 gallons. I can tell you from experience, that a boat the size of Weekender will use all of 5 gallons, if not more, depending on how neat you are.
Some quick estimates of Weekender suggests about 150 sq. ft. of exterior hull surface (not counting the keel). You'll probably have to do the sides in one long panel of fabric each (7 yards total) and the bottom with two passes down the centerline (another 7 yards). So, 14 yards at about $8.50 a yard is less then $120. Where does this leave an exterior sheathing job? About $280 for 3 gallons of epoxy, including hardener and 14 yards of 8 ounce cloth. Not bad really. Of course this is the bare minimum. You should also sheath the decks, cockpit and cabin top and sides too. This will likely double the costs of the materials, but still a reasonable thing considering now, the whole of the exterior is sheathed and water proofed.
When I bought the materials for my Vacationer, it took all most the entire 5 gallons for the bottom of the hull. I needed 2 more for to finish the cockpit and top side. As for fibreglass cloth, don't recall the amount I bought, Paul's estimate sounds like I'll will work. Total cost to me back then was about $1100, Your cost should be less as the vessel is smaller.
Greg
Hey Paul quick question
 I was looking at epoxy/fiber glass stuff on bateau.com
whats the difference between:
  - Fiberglass wide knitted fabric (Biaxial, Triaxial, and Uni-directional Knitted fiberglass)
  - Fiberglass wide fabric (woven and matt) Various weights of woven cloth and matt to choose from.
and what weight of cloth do you recommend using?
got a long way to go before I get to the fiber glassing but figured I'd ask.
There are lots of different fabric types.
Knitted fabrics are the strongest of the bunch you've mentioned. The construction of these fabrics lay fibers (yarns) in a specific orientation. A uni di has all the fiber going in the same direction and these are lightly knitted together, so they don't fall apart when handled. The knitting is usually light cotton thread that can be ground off after it's cured, without damaging the strength of the laminate. Uni di's permit you to place the strength of the fibers along the anticipated stain paths, greatly improving the laminate's abilities. Because a single layer of uni di only has fibers in one direction, you will have no cross grain stiffness, so . . .
Biax and triax are also knitted fabrics. These have stacks of uni di, layered together at specific angles. You'll often see me recommend a 45/45 biax tape for chines or seams. This is two layers of uni di, knitted together, with a 45 degree orientation to each layer. You can get other orientations if you have special needs. Triax is the same thing, just with three layers of uni di knitted together.
The knitted fabrics where designed specifically for "high modulus of elasticity" resin systems (like epoxy) and impart the highest strength to weight ratios available, without getting into the really fancy stuff like Spectra, Kevlar and carbon, which cost ten times as much as conventional fabrics.
The conventional fabrics are divided into three categories, mat, roving and woven cloth. Mat is randomly oriented cut 'glass fibers, bonded together with a binder or sizing. It's use is to "bulk" up a laminate. It requires huge amounts of resin to wet it out, offers very little strength for it's weight and is completely unnecessary with epoxy. It was invented, to compensate for the older polyester resin system's lack of elasticity modulus. It does do one thing well in epoxy laminates though and that is prevent "print through". I'll use a mat "veil" over cloth (less then 2 ounce) as the final layer, so the cloth weave pattern doesn't "print through" the paint. This can save time and does harden the surface too.
Next up are the woven fabrics; roving and cloth. Roven is bundles of coarse 'glass (called rovings) and these are woven into coarse fabrics. It's also a bulking fabric, but has good strength. It's heavy and takes lots of resin and skill to work with. This fabric isn't necessary with epoxy either. The lightest roving you can get is 18 ounce.
Lastly is regular cloth, which is yarns of fine 'glass, woven into a cloth. It looks like a table cloth in lighter weights and is made on a machine much like that used to make table cloths. This is the fabric most everyone uses and it's available in weights from 3/4's of an ounce to 20 ounces. The interweaving of the yarns, makes this fabric weaker then the knitted stuff, because the yarns are crimped to a degree when they go over and under each other. Under load, these yarns stretch out as they try to straighten from their "undulating" shape in the cloth, which usually exceeds their fiber strength. The knitted fabrics are straight yarns, laying on top of each other so they take on any load immediately, making them much stronger.
There are many other fabrics, but most are what we call a combo fabric, such as 1708, 1815, stitch mat, promat, 0/90 mat, etc. These products take two materials and marry them, to speed up lamination. Most are bulking fabrics used in polyester laminates and aren't necessary, nor desirable in epoxy. A common one of these are the combi mats, such as 1708 or 1810. These are woven roving knitted to mat. Again, you don't need, nor want mat in an epoxy laminate, unless you just want a weaker, thicker and resin thirsty product.
Lastly are the tapes. These are just like the roll fabrics, except in most case the edge has been sealed with heat or sizing to keep them from fraying. I use a lot of 45/45, six inch wide, 12 ounce biax tape. I get it on big rolls to save money. It's easier to use then cutting strips from a roll of biax fabric, though it does cost a little more as tape.
For covering the hull you want regular cloth. Only the weight is important. 4 ounce and less, is completely transparent when properly wetted out, so it's ideal on areas where you want a varnished finish. 6 ounce is just barely visible and 8 ounce is plainly seen. Most hulls get 6 to 12 ounce sheathings, with 8 ounce being the most common. A single layer of cloth will not make anything stronger, but will make it more water tight and greatly improve abrasion resistance. If you want added strength you need at least 20 ounces of material and this is pretty flimsy at best (20 ounces of biax is "kind of" stiff).
If you're looking for a "canvas covered" deck appearance, then 6 ounce cloth, without filling the weave is a very close match. If you have areas you want more abrasion resistance, then double or triple the layers of fabric in these places. Some like to use Kevlar along the bottom of the keel. I say it's not worth it. The cost alone is painful, you need special tools to cut it and if you try to sand it, you'll just get this fizzy crap that has to be filled and faired in.
Okay there's the bell, class is over . . .
There's no test Bob. This is just a FYI post . . .