Fiberglass cloth or not?

[Barry Beard]

I'm working on a 1945 plywood runabout. It may well not be worth restoring, but I've started into it now. I've used chemical stripper to remove the paint on the hull and gotten down to the fiberglass cloth. There are many divits in the fiberglass cloth. I'm thinking I need to remove this old cloth, sand the hull and start anew with new fiberglass cloth? (the boat is 14 foot) I'm looking for suggestions and advice regarding 1., alternatives to using the fiberglass cloth (or is that a necessity; I'm definitely a novice); 2., how to put the fiberglass cloth on properly (or best resource for that information); and so forth. I appreciate your response. Thanks. Barry *see the accompanying photos . . .

[Raggi_Thor]

West System has some printed guides, I suppose other suppliers also.
Here is one online:
http://www.westsystem.com/webpages/userinfo/manual/index.htm#2.4

[alan white]

The cloth will need to come off. Once the hull has been de-glassed, the dings, dents, and gouges are filled. Then sand the hull. If it is fir ply (and it probably is), you must use a very coarse grit to avoid getting a wavy surface.
Fir has both soft and hard grain, and sanding with too fine a grit leaves the harder grain standing higher. (filler--- West System Microlight).
Once sanded, use epoxy and a layer of 10 oz E glass, and West System epoxy (105 resin and 206 hardener). Maybe a gallon of resin will do the job.
Many other things could be said, but you should get the printed guide recommended by Raggi. Then you'll have more questions, I'm sure.

Alan

[Barry Beard]

Thank you Alan.

[Barry Beard]

Thank you Kevdja.

[Barry Beard]

Thank you gentlemen.

[lewisboats]

why remove the existing cloth...? Unless there is rot or some other adhesion problem...fill and fair everything with some slightly thickened epoxy and re-glass with a layer of 4 oz, fair it up, sand paint and polish and be on your way. Don't add additional work where it isn't needed.

Steve

[Barry Beard]

Thanks Steve. There are adhesion problems in places and it seems the chemical paint remover also got after the cloth in places. Being a novice, I need to clarify something: Does "fair it up" mean using a long sanding device that keeps things contoured appropriately without making small sanding dishes?

[Flumixt]

Practise.

Practise glassing a piece of wood both horizontaly and at a steep angle like you have on your boat sides. Small pieces will do like a foot square. It's time extremely well spent; won't take long. If you can tilt the boat while doing the sides that'd be best.

Especially on the sides the resin will tend to run down just after you think it won't. Put lots of thixotropic powder in the resin to stiffen it and have a couple (several?) heat lamps ready as soon as you've wetted out the cloth at any particular spot to aim on where you have just worked and start the resin to kick off ASAP. Figure about 30-60 minutes for this. Do small lengths to keep it under control. Then keep yer eye on it till it does kick off or you'll sure wish you had. Might have to keep working it uphill with a brush, blade or roller for a while till it stiffens.

If you practice this on the spare pieces first you will learn a lot and won't get caught with a pot full of resin dripped on the floor. You can also go a tad heavy on the catalist which might hasten the kick off but practise that first. You'd have to keep track of the mixtures and reaction times ie make a chart. The practise boards will help you guage the thix powder too. You'll be amazed how much can be stirred inna the resin. You'll learn how close to set the lamps for effective heating w/o burning up your boat too.

This turned out longer than I expected. -jimbob

[alan white]

Regarding fairing: This is a matter of feel. Plywood, or any single curve surface isn't too difficult. Using a batten, check the hull over for low spots and areas and fill those first. I usually make a 24"-32" long longboard by cutting a 6" 36-50 grit sanding belt (normally used on a stationary belt/disc sander. This is then glued to (usu) a piece of 1/4" ply or masonite with construction adhesive and clamped overnight. Other sizes may be useful depending on curvature. In the case of ply, removal of wood isn't desired, so adding fairing compound is how to do it. Stick with a coarse grit because it is less suseptable to riding over harder surfaces. Running your hands over the hull is the true test of fairness. If you tape all corners before fairing with two layers of tape (3" is okay, offset so the first layer is an inch more on one side than the other, and then opposite with the next layer), you can run the big cloth (after fairing) up to, but not over (avoiding doubling) the corners.
Fairing before glassing is a good idea because the glass has a perfectly smooth surface to lay on, and the weave is protecting the softer fairing compound underneath. It's also easier to guage your additional sealer coats for uniformity if you see the weave filling completely (two additional coats of pure epoxy finish the job ready for final sanding and prime/paimt.

Alan

[Barry Beard]

JimBob and Alan, Thank you. I've got lots of tips and info; now need to get my butt out and into it. Just like jumpin' in that cold water. Barry

[barthautala]

Im a newbie. You only use fiberglass cloth on the surfaces you plan on painting correct? Otherwise, you wouldnt get the pretty wood shine. Am I correct here?

[alan white]

Fiberglass is almost invisible. However, there's no need to use it above the waterline except for abrasion resistence or strength or water-proofing. Canoes that are strip built almost always are glassed and then varnished to add UV protection. They appear to be only varnished, however.

[barthautala]

thank you for the explanation. I never knew the cloth came out invisible. The only experience Ive ever had with fiberglass is the stuff on my dads bike. Which when broken looks white......that just must be the primer they use to paint over.

[Barry Beard]

Alan, I never realized you could varnish over fiberglass cloth. Do you need to get a special grade of fiberglass cloth to have it appear invisible? I guess I've never really looked closely at a varnished hull to try to detect the cloth. Thanks. Barry

[USCGRET/E8]

If the wood is in good shape after removing all the fiberglass, it would be a whole lot easier to not re-glass it. Sand and fair it smooth, then use some real good marine primers and paints. This would make it more original and save a lot of time and $. Glass reinforcement is not necessary for normal use.
Back in the 60's and 70's it kinda became a fad so to speak. Everyone thought it would put and end to their maintenance woes. Good Luck with it.

[USCGRET/E8]

This is one of my several wood restorations with no glass.

http://i161.photobucket.com/albums/t239/MACHTECH1990/OB.jpg

[Raggi_Thor]

Search for "twill" and cloth. That's a fabric that is easy to wrap around round corners etc. 160g/m2 is impossiblle to see, looks good.

[alan white]

Alan, I never realized you could varnish over fiberglass cloth. Do you need to get a special grade of fiberglass cloth to have it appear invisible? I guess I've never really looked closely at a varnished hull to try to detect the cloth. Thanks. Barry

If you've ever been to a wet tee-shirt contest, you'll notice that even white cotton can become somewhat invisible when saturated.
All fiberglass is pretty much the same--- that is, glass fibers. Cloth is more invisible than woven roving or mat, mostly due to the ease of working tiny air bubbles out of it, and it's being far thinner (which is why you can't see through a wet white cotton towel, hence there are few wet towel contests).

Alan

[Barry Beard]

Having a great fear of spending a lot of time and money messing with fiberglass (particularly in view of no experience; though the practice board idea sounds good), I really like the idea of getting the cloth off, prepping the wood good and just going with good paint and primer. I'm curious what other members might think of that method of doing a wood boat and what their experience is with that. I very much appreciate all of the information I've received from you folks and thanks to Alan, I guess I wont be hosting a wet towel contest at my next barbecue. Barry

[alan white]

You know, Barry, it is okay to do without glass in some cases---- harder if you don't tape the seams, but I'm going to suggest you do tape the seams where the sides meet the bottom at least, and anything else below the waterline, including where the plywood butts together. That area will be painted anyhow. If the stem is covered by a stainless V, tape under that, and if it doesn't, consider making one and that will allow you to cover every underwater joint.
This taping of joints is 90% of a whole glassing job in terms of water intrusion and strength, and yet uses a fraction of the time/materials.
Originally, any ply boat would have depended on a sealant between the parts to prevent leaking, but you can't really inspect those joints without actually taking the boat apart unless they are really bad.
Glass tape covers rather than beds pieces in sealant, so you won't have leaks if you tape the seams regardless of whether the sealant is dried out and cracking.

[Poida]

Allan, you certainly have educted me. I always thought that something was either invisible or visible. And something can't be almost invisible. You can either see it or you can't.:p

Oh I love this.

Poida

[alan white]

What about limited visibility? It's not like a pregnancy can be limited. You're either pregnant or you're not (and I hope you're not). Ah, but visibility is an entirely different kettle of fish (you know, those fish you can see through the skin of?
Mr. Clever trousers.

[Poida]

Visibility is the ability of a person to see, may be due to their eyes or an obstruction.

Invisibilty is the state of the object, you can't see it because it is invisible.

Invisible fish must be the ones I catch.

Perhaps my smart trousers may suggest the word opaque or translucent and I think you can have a semi translucent object, actually I don't know what translucent means but it sounds good.

Best of luck with your boat Barry and don't listen to Allan or your boat will disappear. Or nearly disappear.

Smarty Pants

[alan white]

I wouldn't listen to my trousers if I were you. Especially if the back is talking (though I'd love to watch the discourse--- on video).

Now, regarding the deeper problem. Poida, in the last twenty-four hours, you've been a bit slap-happy. I can only guess this is due to a release from anxiety, perhaps a negative medical prognosis or other hubris-inducing factor.
Improper paragraph structure indeed. Now, imroper word usage too.
A more comprehensive analysis can be derived from the last joke you wrote.
Here we have a drunken Irish cripple who, in his alcohol-induced haze, has forgotten that he is a cripple, enough to miraculously make his way all the way home unaided.
This is significant, as there is a truth to the story. Sometimes, we come to realize how perception deceives us, and like Lazerus, we are raised from the dead and get a second chance.
Or, like the fabled Sleeping Beauty, we undo the curse, and instead of dying, we sleep for a hundred years.
It is truly remarkable!

Alan

[Poida]

I'll have to agree with you there Alan, because I have no idea what you are talking about.

But then I have no idea what I'm talking about either.

Poida

[mydauphin]

Quick idea, I dont know if your looking for this look. Above the waterline, I used mahogany dust sprinkle into epoxy to give it a wood look. Sand, Clear epoxy layer, let it cure a to tacky. Sprinkle wood dust on epoxy, push it around with brush around liberally but not into epoxy. Let it cure. Sand lightly cover with other layer of very thing epoxy with UV coating...

[PAR]

Alan is correct, some 'glass fabric weights will become invisible, others less so. A 4 ounce, or less, finishing cloth will become invisible after wetout, literally not able to see the weave with your nose on the surface. A 6 ounce cloth will be nearly invisible, unless you catch the light just so and are within a few feet, where then you may see the faint pattern of the weave. Looking down, at dock side, it would be difficult to see 6 ounce, without having a reflection to help out. Cloth weights above this will be plainly visible at any distance.

[Eagle Boats]

This topic is just what I am looking for. We are reintroducing a 16 foot sailboat after at least a 10 year hiatus. Due to problems that some people were having with the rudder, I need to find a better way to build the rudder. The rudder is built in two parts, a lower rudder, built of mahogany, and an upper rudder, built of mahogany and marine plywood. The upper rudder, after years of useage, would break. In all likelihood, the upper rudder was weakened by water intrusion into the plywood. I would like to use the same construction as was used previously, but also add a layer of fiberglass cloth to the upper rudder to prevent water intrusion. I want complete transparency to maintain the asthetics, but I want to make it stronger and watertight. Should I use 4 oz or 6 oz cloth? In addition, the boat has hatch boards made from teak marine plywood. Over the years, the boards would delaminate. I was thinking about covering the boards with glass as well. Any thoughts?

[alan white]

I would guess that inferior ply was used the first go round, since delamination should not have occurred. I would perhaps seal the edges of any ply liberally, because that is where it is most vulnerable.
Regarding the upper rudder, a simple coating of epoxy is adaquate and well advised too. Cloth is unnecessary expense. The cloth is primarily an abrasion thing on a lower rudder, and an upper rudder will last very well with a couple of good coats of epoxy.

Alan

[PAR]

Rudders are a difficult thing to make using solid lumber or plywood. This is a place where inert materials like GRP do shine well.

A few coats of epoxy will not help a solid stock or plywood rudder much. Though I usually agree with Alan, the $20 a month (:rolleyes: ) he sends me to arbitrarily boost his "reputation" points isn't affecting my opinion on this subject.

Rudders and their cheeks take a lot of abuse. The leading edge, trailing edge (oddly enough) and the faces of the mating surfaces within the cheeks, see much more abuse then a few coats of straight epoxy can handle, when on wood.

Let me guess, your rudder head is comprised of two outboard solid lumber cheek pieces, capturing a plywood spacer, which is just thicker then the rudder blade? The less dimensionally stable solid lumber cheeks moved more, in relationship to the more stable plywood spacer, pulling, twisting and testing fastener ability to hold the assembly together. This of course leads to moisture getting into the cheeks and spacer. Since the spacer is plywood and doesn't hold fasteners as well as most solid lumbers, the holes "egg" out, rot gets started and the down hill slide is on.

Rudder blades of solid lumber are best made of vertical strip plank construction, with alternating grains in each strip. Edge glued and fastened, these perform quite well, with much less movement, cupping, distortion, etc. Given a sheathing of cloth, much more stable. A clear finish requires 4 ounce, with 6 ounce being just barely visible at 4' away in very bright light. Neither of these weights of fabric will provide a lot of abrasion protection, but better then none. I'd use a couple layers of 6 ounce as a minimum, 8 ounce would be better, but it wouldn't be a bright finish. Only 4 ounce or lighter will be truly invisible.

Cheeks, particularly hardwood versions, are very prone to moisture gain movement. Inserting a sheet of Teflon or other slippery (HDPE, etc.), inert material between the cheeks and the blade can help tremendously, especially if a tight fit is desired.

Teak is a preferred blade and cheek material because it's much more stable then other hardwoods when wet. This could be said of most of the oily woods I guess.

Personally I use pure GRP or form cored laminates for blades, aluminum or stainless for cheeks, bush out the pivot, etc. so no issues can result. The same with center or daggerboards.

In your case Eagle Boats, I'd embalm the plywood with epoxy, sheath it and ditto the cheeks and blade. I'd also reinforce the leading edge with metal or my favorite a epoxy soaked section of double braid, let into a cove, carved into the leading edge. This takes all sorts of abuse, without injury to the surrounding wood and looks pretty cool. I'd also bond all fasteners and pivot hole, even if they are bushed with an inert material. I don't know how we manage to ding up the trailing edge of blades, but it happens quite often, as if we sail backwards, blindfolded a lot. This is another area that could use some metal reinforcement (so you can maintain a crisp edge).

[alan white]

Well, PAR, I admit my last payment was a little slow in getting out. I've got other forum members besides you to consider.
True, rudders suffer some bad punishment. I glassed mine, over 1 1/2" of sculpted okoume, single layer 10 oz, double taped on the leading edge, and no glass at all above the waterline. However, the mechanism is a back-latching tiller that removes out of the slot when raised high enough. The rudder has no cheeks, as these are on the tiller. An adjustable bolt maintains exactly the right tightness by pinching the rudder head. I like this system very much as it trailers well by slipping off and there are no rudder cheeks to worry about, the tiller cheeks being high and dry. It is not as strong as a rudder with cheeks, admittedly, but being maybe 5" fore and aft, the rudder head is quite strong. I can't see how glassing it would offer much more in terms of strength, and the only point of wear is the area swept by the tiller cheeks, easily adjusted, and easy to re-surface if ever need be.
On the other hand, I baby my boat. I am not building a boat that will potentially be used hard by people who sail backwards. Your points make sense if the boat is likely to be treated like most people treat things nowadays.
A good article in WoodenBoat mag described a proper cheek rudder build having two layers of cloth throughout over a ply lamination. The boat shown was not a dry-sailed boat. I think your description of the ideal construction was very similar to that.

Alan

[rwatson]

Its only invisible IF the wetting out is very thorough. and it shows up all the faults in the timber underneath. If you want a quality wood finish on *this* hull, the work would be horrific. It would be better to cover the old ply with a new ply veneer ( or teak strips) and then glass it over

Good luck - :)

[LP]

Par,

Great little tidbit about the double-braid. Rereading your post, you let it into a cove, so it not buried too deeply. (?) Do fill the weave, or glass over it with some light cloth?

Back to the original post,

I don't think I can add more to what has already been said other than, I don't think a bright finish is in store for this boat. I think that is perfect candidate for learning to epoxy and glass. It should look nice with a good painted surface when all done.

[PAR]

It's not that uncommon a trick (double braid, leading edge), I've seen it for many years. The cove keeps it in alignment on the edge and cradles it a touch, but not much more. Fill the weave and you don't need fabric, though if you plan ahead (right) and are sheathing the sides, then this is a nice place to easily terminate the fabric. You just finish out the leading edge fairing as you take care of the edges of the fabric on the sides in the same process.