Fiber Cloth on new Wooden Hull

I completely agree, did before and do now.

 

Right. A lotta work.

 

It is said that for wood hulls it is better to use polyester cloth than glass:
it is more abrasion resistant
it moves better with the wood

see http://www.woodenboat.com/forum/showthread.php?t=6640

 

I do not think that Xynole would be found in Turkey. So the following post is an "aparte" from the thread's subject. It's better for Teoman to stick with a well known and "cheap" material. Plus the added diagonal strength of 2 layers of glass will be a welcome plus for his boat, which has too much longitudinal wood fiber for an EP wood construction.

The French Navy had tried a lot of sheating materials for the project of a mine hunter in composite EP wood, with true engineering tests including cyclic fatigue and accelerated aging in salt water. Nothing that a common boat builder or West System can afford. Evidently, the results are not public.
A mine hunter must survive to a lot of factors, specially the close explosion of a mine (this goal has been met with polyester/epoxy/vinylester resins, UD glass, plywood and a lot of different foams)

Polyester "cloth" like Xynole adds nothing to global strength and weights a lot. It's finally like a mat close to the coremat and similar. It resist to abrasion mainly because the result is very thick.

You can get close results with a good cotton or linen cloth. Simple bulk agents for keeping more resin, nothing more. Air bubbles may be problematic with some tight woven clothes.

Nylon or polypropylene cloths are a pain, because of their low density (it floats on the resin), difficulty to sand, and very poor adherence. After all lot of peeling ply cloths are made in nylon and/or polypropylene...Good impact resistance, lot of reparation after a big shock.

Kevlar, Vectra and consorts are more interesting but so expensive. Adhesion is not the best, and using this clothes is a pain. Difficult to cut, impossible to sand. The kevlar fashion in boat building didin't last a lot, and these fibers are used now where they belong: armors, sail clothe, ropes etc.

Carbone is not good as sheathing material, too sensitive to impact. The price also...

So fiberglass cloth is difficult to replace. It has a lot of advantages; price, resistance, excellent adhesion with the proper surface treatments (and it must be kept perfectly dry, as the silane or volane surface treatments are hygroscopic. In humid conditions the fiberglass must be dried in a oven.), easy to wet, and transparent so you see what you're doing. Add it can be sanded very well, and not problem to cut it.

A note about the thread in Wooden Boat you mention; the Xynole seems to have better peeling strength than fiberglass. It's simply because the fibers are too weak to break the EP. Cotton is also impossible to peel. Or you put enough fiber and EP to break the wood substrate.
Fiberglass is stronger than the EP, so the glass can fracture the EP when peeled. Mesh steel wire do the same...

 

There is Poly cloth in Turkey, (and every sort of peelply too).

But in this application, as Ilan said, it has no advantage. A well done pattern of glass cloth is the way to go for Teoman.

 

All we can do now is to wish to Teoman good luck...he has a lot of work to do, but with care an acceptable result can be obtained.

This thread illustrates that a any boat is an engineered project, which requires a perfect knowledge of boat building by the designer. No mix of systems (hybrids accumulate often the disadvantages, none of the advantages)...

 

Good afternoon,
I apologize for the late reply to all your posts, I was on a long flight away from Istanbul.
It was a great pleasure to read through what you all said and I thank you for that.
First of all I researched the adhesion of epoxy to chestnut. A university in the Black see made a research and thee results were more than acceptable. No problem was sighted.
I will still do the test on my own as you suggested. thanks for that.

Concering the epoxy to be used, I checked West epoxy specs, and elongation is reported to be 9-10 % . This sounds good I believe.
West products is a little more expensive than others here, but I think it will be worth it. What you think about the 9 % ??

Finally I will go with 2 coats of resin on the inner, and probably a 4th on the bilge, and 2 coats of fiber on the outside at 45 degrees each, and 2 final layer of resin only on top of that.

Thanks for your time guys . Hope to send you the finished picture someday

 

Layers of resin can be applied thick or thin, like paint. If in doubt, go thicker. The surface inside and out should be uniformly smooth without dry-looking areas.
Three coats inside would probably be best if in doubt, and two outside over glass will probably work fine. Look for that solid semi-gloss appearance.
West is good stuff, very easy to use and forgiving. I recommend it for the beginner. Later, when more experienced, other cheaper resins can be used.

 

Fantastically informative thread folks points to one and all. The parts about not mixing methods was most helpful as were the bits about wood species and moisture induced stress

cheers
and best of luck
B

 

So when I start with the epoxy layers, would you guys recommend that I wait until each layer (resin layer only) is fully cured then sand it prior to next layer, or can I go ahead and apply the next layer before it drys and cures ??

 

If you apply coatings wet on wet, or before the previous coat has completely hardened, no sanding is needed. You'll be achieving a chemical bond rather than a mechanical bond.
Most of the fairing should be done before glass is applied, so it shouldn't be necessary to do more than scuff between coats to take down, and fair lightly just before the last coat, using microlight or simlar fairing compound.

 

Well,

what Alan wanted to say (I assume) was something like my recommendation:

Get ALL your friends out of the bush and do the entire epoxy work in one single go !!!!!!!!!!!!!!!!!!!!:!: :!: :!: :!:

You will feel the need to spend some Raki later, but that is no expense compared with the labour and cost of sanding.

And more important, you get a homogenous layup which never will delaminate!

Sorry for my late reply, I am sailing at present.

Regards
Richard


Boston

could´nt find the points again, you do that hidden...............

 

Yes. And cool temperature is on your side, and so is tropical hardener. In some cases, you could draw the wet-on-wet job for weeks. Then you'd have some real control. when finished, put the heat to 'er.

 

Quite important point! thanks




dunno why, sometimes have the impression we like to agree....

 

Ok I think I get the point. Thanks...

Richard there is one epoxy on the Turkish market called "Teknomarin" ERA 4000. Did you heard about that one ??
any idea, would you recommend it ??