new low cost design competion

Thanks, AK
As I said, I didn't build the other boat, so I'm not too sure how tough it was to cut, fill and sand. It was some work, I'm sure. I thought the reason for Dynel had something to do with some expansion co-efficient being nearly the same as that of wood at varying temperatures. The story I was told was that ordinary glass doesn't expand and contract the same as wood....on a small boat you wouldn't notice it as much anyway, I suppose, but the varying rates of expansion supposedly set up some sheer forces that could lead to de-lamination. The guy told me that epoxy resin also is superior to polyester resin for the same reason....and was in fact the reason why polyester didn't work so well on larger dimension boats. I've recently read though, that the problem can be solved by putting on a 'primer' coat of polyester resin cut with some sort of solvent, prior to putting on the final polyester/fiberglass coat. Haven't researched this further....may be bad science, so don't build anything based on this comment! LOL
You're right too, that materials are more expensive here in Canada than in the US, not only that, but our dollar is less than the US dollar.... which means that you have to spread it a little thinner to get the same results... worse, there are some products that aren't available here and when we order it in from the states, we have to pay customs, duties and taxes on it. I'm not complaining though, it's a great country with lots of places to explore, very little marked by the passage of man. When you get out of the big cities and off the highway....it's like stepping back in time a little. The do-it-yourself attitude is still big here. And building a small, but able boat of one's own, with barn-carpenter skills, is fairly ordinary. This contest should really have an appeal for these folks....but then, they probably don't spend too much time on-line....they're too busy doing it, aren't they? LOL

 

Lightkeeper, if your intrested in the polyester problem Seamens Fibreglass used to have some good info on that in their bochure, probably have it on line if they still exist. You did a good job on that little dory. She'll get you home, with fish too This thread has got me to thinking.. you know next year when CG sends us down for training week instead of trying to find a good restraunt and looking at the same tourist stops again, we should build a quick and dirty sailor in the evenings, give us something non turesty to do. You bring your guitar and I'll bring my banjo, we'll busk on the street to pay for it LOL. That would make a fun contest have to build a boat with what you earn in 3 days. Too many morning shifts I'm thinking silly.

Dennis

 

lampy;
if we were busking, there wouldn't be time for building....or do you not intend to sleep? Next question, where to build the dang thing, followed by "does one of us take it home afterwards, or donate to charity? It'd add an interesting dimension to this design contest.

 

Take this for what it's worth; I'm just passing it on--third hand, no less.

But according to John Riding, a gentleman in France quoted by George Buehler on his web site, the problem is that the polyester in contact with the wood never cures properly. His solution is to indeed do a prime coat, but use accelerant in it.

"I would like to add a little, namely, that the chemicals present in all wood, can and do inhibit the curing of the polyester resin that actually soaks into the wood. So a resin seems cured, and on you go, and add a bit more glass, then finish it all off, then some years and several thousand twists and shakes later the whole darned skin tries to fall off. The resin never cured IN THE WOOD. I learnt fibreglass from one of Australia's masters, Geoff Baker, who had a factory in Mona Vale, Sydney, and built Illingworth 'Top Hats', and the various Brolgas and Boomerangs from the board of Peter Joubert.
Geoff was adamant; Use cobalt napthanate, the standard 'accelerator' additive, 2% or a little more if the wood was 'green', added to the resin BEFORE adding the catalyst. The CN is explosive when directly in contact with catalyst, so TAKE CARE. Mix it well with the resin before catalyzing. With this accelerated brew, paint a primer coat on all the wood to be glassed. It will go off quickly, but, most importantly, will cure right into the wood, and will never let go. Continue with whatever layup you fancy from here on; the stuff is now well bonded. It will fix those rudders that keep shaking their skin off."

http://www.georgebuehler.com/Polyester and Plywood.html

 

Oh please. What chemicals, what reactions, like this hasn't been tried many times to no avail. We know why polyester doesn't stay adhered to wood, the great disparity between the two materials modulus of elongation, unless beaten by another physical disparity, such as rolling shear.

Wouldn't it be nice if we could just use a technique and all would be well with polyester on wood.

All wood that I'm familiar with is: carbohydrates (saccharides), polysaccharides (carbohydrate chains), lignin (biopolymer - a hydrophobic racemic macromolecule), cellulose (glucose chains), hemicellulose (monomer sugers) and, and the obvious extractives which aren't naturally occurring. So, how does polyester react with these to prevent a cure? Does it prevent the hardener from being a reagent?

In short, it'll take considerably more then some generic spouting off by a Buehler fan. What's to support this claim? This isn't a reflection at the messenger Troy.

 

Cobalt naphthanate? I never heard of it but it sounds expensive. Copper naphthanate; That I've heard of, and used. How is it any different in the long run?

 

Hi Hoytedow;
I just looked up cobalt napthenate on Wikipedia;
"Cobalt(II) naphthenate is a mixture of cobalt(II) derivatives of naphthenic acids. These coordination complexes are widely used as oil drying agents for the autoxidative crosslinking of drying oils. Metal naphthenates are not well defined in conventional chemical sense that they are mixtures. They are widely employed catalysts because they are soluble in the nonpolar substrates, such as the alkyd resins or linseed oil. The fact that naphthenates are mixtures helps to confer high solubility. A second virtue of these species is their low cost. A well-defined compound that exhibits many of the properties of cobalt naphthenate is the cobalt(II) complex of 2-ethylhexanoic acid. Often in technical literature, naphthenates are described as salts, but they are probably also non-ionic coordination complexes with structures similar to basic zinc acetate.

The catalytic properties of cobalt(II) naphthenates are similar to those of related compounds containing manganese and iron. Such species are sometimes classified as active driers." Active driers are catalysts that feature redox-active metal centers. Such centers promote redox reactions with hydroperoxide-containing intermediates"
As PAR noted, not sure that wood has any chemicals that would interfere with polyester resin hardeners or the resin itself. I would want to see some more empirical data on this one, too. I haven't used cobalt napthenate, myself, but I have used what was called "Japan drier" on paint (non marine application) and though it did seem to dry the paint faster, it also seemed to make it more brittle (purely subjective observation)....and if cobalt napthenate does the same to the fiberglass coating of a wooden boat, nah, wouldn't want that. But again, that's an assumption. it needs research. At least cobalt napthenate is reported to be cheap. Experiments shouldn't be too costly. Anyone willing to try? Epoxy resin is a relatively expensive part of small boat building....polyester if it could be reliably used, would be a lot cheaper.

 

Lighten up, Paul. You're coming on a little strong there, when you dismiss the man as just some Buelher groupie. Whether his theory on why the method works or not is correct, he does cite a successful builder who used it.

People slapped a whole lot of polyester resin over wood and plywood before epoxy became readily available. It fell off some boats, and didn't fall off others. Since the professional builder who used this method of priming apparently managed to stay in business long enough to build some name boats, there's at least a possibility he knew what he was doing....

 

Sorry Troy, I didn't mean to be quite so aggressive. I just get pissy when statements are unsupported historically, chemically, physically, etc., particularly when George's techniques are involved. His building methods worked great when he dreamed them up in the late 1960's and early 70's, but apply less and less as the decades wear on since. This isn't his fault, it's material quality issues and cost per pound of these building materials, which is nothing like it was back then (I wish it still was, but it's not).

I lived through the "polyester era" and most of the sheathing jobs fell off, not just some, but most, a very high percentage. The ones that didn't where stapled on and/or applied very thick, so making a hull shell over the hull shell. This isn't a sheathing but a redundant hull.

I'm familiar with cobalt napthenate, though only to know what it is. I don't see it's affect on the molecules in wood, which doesn't mean there aren't any, it just means my understanding of the chemistry, which isn't that of a novice, doesn't see a conflict.

Japan drier is a wetting agent that is quite complex. It's basically an oil catalyst with a few modifiers to help flow rates. Yes, it does make alkyds harder and more brittle, depending on ratio. It can also dull clear finishes, so ratios are kept low in varnishes.

I guess my real point is, if this French man's technique was effective, why is it so obscure? A simple wash, that puts all the rotten transoms, soles and stringer repair folks instantly out of business, seems a reasonable goal, especially if the wash is "relatively inexpensive".

 

Although polyester is cheaper than epoxy it is harder to use and its long-term reliability has been challenged before. I hadn't heard of the glass sheaths separating but it is one more thing to worry about.

I read in various posts that glassing and/or resin saturation may not fully waterproof the wood it covers. Most adhesives lose adhesion when the wood becomes saturated although epoxy does not, but if polyester has that problem it may be a cause of sheath separation.

We seem to be off the topic ...

 

AK;
You're right, we are off topic. Although, the capacity to use polyester resin, may be interpreted as an exploration of an idea to get more boat, and perhaps more speed per dollar. Sawmaster, in his original post, seemed to be asking for a contest to actually be set up. Rules and guidelines established. Does anyone actually want to DO this contest? IS there an organization similar to the British AYRS anywhere in North America....or is this forum it?

 

It's be an interesting concept if it worked.....

Part of the issue could be that winning would probably be fairly simple. Build a light ply hull to a proven design and you're a long way ahead of the pack.

How light? Well, someone on this thread mentioned 1/4"/6mm ply. That's for offshore racing yachts....actually I think I did a Sydney-Hobart with 6mm ply decks.

Moths were built in (if I recall correctly) 1.8mm ply hull bottoms, single skin. The ply for the foredeck of my last Moth was, I think, 1.2mm (?).... repairs were done by cutting patches with sewing scissors, but nail scissors were also heavy enough.

You certainly don't need glass. There were plenty of 110-140lb Cherubs and Gwen 12s back in the 1950s which were tough enough to carry a trapeze and big spinnaker on a bay that's similar to SF's Berkely Circle course. A ply Moth, without 'glass, is about 60lb with alloy wings. The first Farr 3.7 ever, built in 1971 from 4mm ply, weighs 110lb and is still racing competitively despite being a fast trap boat from a windy part of the world, and I'm fairly sure there's no 'glass on the ply 3.7s (apart from perhaps some chine tape). A Medium-Dribbly (late '60s) style NS14 comes in at around 140lb in 4mm (IIRC) ply and will last decades going about as fast as a 19' Lightning and it has no trap, no spinnaker and half the upwind sail area of the Lightning.

Quickest of all, for size, would be Phil Stephenson's Moths - 11lb hulls (before decking) being completed at 14kg (31lb) with wings. Carbon wings can be built from scavenged broken windsurer masts. Even if you didn't build a foiler, a "seahugger" Moth to Phil's design is going to fly.

In a way, such boats encapsulate the issue; there were world-class designers creating boats in ply years ago. Such boats aren't inherently a great deal more expensive than something from Home Depot materials (although probably a lot harder to build, and certainly generally requiring much more care to handle - but who wants to ram docks or drag boats up the beach anyway?) so is there much to be learned?

Cheap rigs and gear are where the big savings come in, surely - and even then you get a better bang for the buck (and better ecological sense) with a revamped old boat.

 

Following your thought ....

Steve Clark has a tortured plywood International Canoe design that could be built from home center materials, except perhaps the egg-crate sliding seat structure which requires serious carbon uni reinforcement. His design was done as an exercise in simplifying, cost/labor reducing and ply-panelizing Chris Maas' String Theory-style boat. Building a Canoe hull and then compromising as needed on mast, seat & rig to fit cost targets would certainly be faster than a Moth.

A Canoe would have an easier time staying upright than a skinny Moth without foils.

--
CutOnce

 

design competition

hey,CT 249,
You bring up some interesting issues.It may be that there is not that much more to learn,if you already know how to build an 11 lb moth or are a master builder able to produce something out of paper thin plywood that lasts as long as the farr 3.7.This competition,however,was conceived for those of us whose skills may not be quite that advanced.The winning design,hopefully,would be simple enough for the backyard tinkerer to build-hence the requirement that the design be self built.While building skills vary,the more simple it is to build,the more likely the winning design would be built by a large number of people.Also note this is a DESIGN competition,so you couldnt just build a proven design out of cheaper materials,(unless it is YOUR OWN design).While I would welcome the participation of professionals,this competition is primarily for talented amateurs,presumably it would be against the monetary interests of the professionals if the competition yielded a design that produced 90% of their speed @ 10% of their cost.
Ed

 

Hi Sawmaster,
I really like this idea but I have some questions. How new does the plan have to be? If it’s say, 12 years old and have had many built but only by amateurs does it still count? Also, who would be judging the submissions? Some contributors here have stated there prejudice in favour of professional builder and designers only. And since this forum covers a world wide audience we couldn‘t all get together at once to show our boats how would you like submissions of the finished product? Would you like to see the designs limited to certain materials or certain amounts to avoid free wood becoming part of the savings? How do you feel about sponsorship, like the sika flex “quick and dirty” competitions? I don’t mean to give you headaches just wondering how restricted we would be.

Dennis