Thread: Advice on glass sheathing

This (unfortunately) sounds so familiar it's not funny.

I've only built one boat so am far from being an expert but will tell you my experience.

My hull was done in a similar way - apply coat of pox then drape cloth over wet layer. The glass had been draped over the boat dry for a day to help it conform to shape and it did that very well. It was then folded carefully so it could be put back the same way. After folding though it did not go back so well and any attempt to move or smooth it pulled the weave out of shape because it stuck to the wet pox. Wherever there were wrinkles that were not smoothed successfully there was too much resin under the glass. It looked a mess.

When it came time to do the deck I put the glass on the dry hull (bare wood - not precoated) and rolled in the pox sparingly. It seemed that as the timvber soaked up the resin it sucked the whole layer down flat and it ended up looking perfect to me. The glass was wetted out properly but there was only a small excess to squeegee off. Fill coats went onto this surface much better too.

I will always use this method for wet out from now on.
Others may say this is wrong - all I know is it works for me.

As for repair, again I don't have much experience, but it seems that the heavier the coat you put on the worse you will make the job. This applies to subsequent coats as well as the wet out.

Unfortunately when we build our first boat it is the hull that is the first large area glassed so we gain our experience on one of the areas that should probably be done near the end.

On the positive side, it is all repairable, and when it is all finished and you sit down for a celebratory beverage you can take pride in having overcome the obstacles. Good luck with the rest of it.

The West System epoxy product info mentions this dilemma and recommends the dry wood method. The glass really presents no barrier to the epoxy soaking into the wood, so really you're doing two steps at once. The only problem can occur with vertical and upside-down/overhead surfaces, where you have to think of some clever way to stop the glass falling down before you've got enough epoxy through to stick it all. This reference may help:

http://www.westsystem.com.au/west_sy...lass_and_tapes

Howdy,

WHEN GLASSING LARGE AREAS
It is in my FAQ in some detail - http://www.storerboatplans.com/Faq/faqindex.html

For the size of boats we are doing and with woven cloth ALWAYS get the glass down smooth then apply the epoxy. If it looks OK with the resin down first you have been very, very, very lucky - well done!

When you do it the easy way you will get a brilliant result!

You don't really need to let the glass "Rest" then take it off. It has no memory. I plan to roll it out on the job once and not take it off again - every time it gets handled it get damaged a bit ,, a few threads pulled here or there or some gunk tangled in the weave. Drape the glass, get it into position a few little pieces of masking tape to hold it in place if needed then epoxy.

This is always true of lighter glass cloths, When you get to the thicker multi layer stitched cloths you do often have to roll out the epoxy on the hull first, but they don't change shape so readily as the woven cloth.

The others are right too about not too much resin.

The way to fix it is right. Grind and fill.

Small areas you can also put the resin on first. Like glass taping or doing areas up to a square foot. Larger than that ... it is usually best to apply the glass first.

Very glad you survived this so well!!!

MIK

thanks guys. I was following the BoteCote booklet which strongly recommended the wet method (wet down hull with pox first) for the inexperienced. Next time I'll ignore that and follow MIKs advice - it makes more sense with thin cloth.

I've just taken the hull outside into the sun and am somewhat less pleased with it then I was last night in the poor light. It looks like I've got a big sanding job in front of me - and I'll be cutting throught the glass fibres quite a lot

Howdy .. it is plywood so the only place it needs to be really strong is across the joins. You can be quite brutal everywhere else.

Does the manual talk about putting a first coat on and letting in cure, or as a straight on process.

I think I knew about that being in there, but had forgotten.

By the way .. this is a really nice bunch of basic topics you are creating ... good work.

MIK

MIK

Originally Posted by Boatmik

Does the manual talk about putting a first coat on and letting in cure, or as a straight on process.

On page 18 it says 'start the wet method by rolling a layer of Bote-Cote thinned with TPRDA onto a bare timber surface. Leave this coat long enough to ensure that air bubbles have been eliminated from porosity ini the timber surface. Lay the cloth on...'

I guess that means its still wet when you put the cloth on.

Arron

It definitely does ... I'll have to remember to say that bit doesn't count. Had quite forgotten that it was in there.

MIK

Thanks Arron
and sorry.
Probably isn't any of us haven't made the mistake of trying to move wetted-out glass.
Probably isn't any of us thought afterwards "THAT was a particularly stupid thing to do
- NEVER do that again."
Probably only MIK thought that someone else might also do it...

Rule of glassing - once it is wet, it stays there. Whatever.

At least you didn't do what I did today... started wetting out with un-stirred epoxy.
Had to excise the wet glass & try as best as possible to remove the hardener from the
plywood. Funny thing was I read in this morning's paper that day-dreaming is a
good thing - helps find creative solutions. Dumb, dumb, dumb.

Stupid question... did you ever tell us which skiff you ended up building ?

cheers
AJ

I ended up building the Oxford shell - http://www.clcboats.com/shop/boats/r...FORDSHELL.html

I chose this because it appears to be the quickest and cheapest to make so any blunders or first-time disasters would not have a great consequence. I'll make one of the open wherry styles next - but they are a significantly greater expenditure of materials and effort so having some experience before tackling them would be good.

The other plus is that I can gaurantee I can lift it onto the roofracks alone. Finished weight will be about 18-19 kilos before rowing rig is added.

Arron

Originally Posted by Arron

So today I glassed the outside of the rowing skiff I'm making. This is my first attempt at fibreglassing and I didnt expect it to be perfect which is good because it isnt.

The problems seem to have arisen right at the start when I thought the glass fabric was 7 metres long and began to spread it over the wetted down boat hull. However it appears it was only 6 metres long and didnt reach to the end, so I decided to pull it up and reposition. It wasnt easy to reposition and the weave got distorted as I did so. After applying the next coat of epoxy the bottom of the boat looked real good but there were diagonal wrinkles along the sides. I guess they arose because the weave was distorted diagonally. I tried to eliminate them, largely by squishing them down with my gloved fingers, and in most cases I was successful. However the worst ones I had to slit open with an exacto knife. This has left me with about a dozen wrinkles on each side, some slit up the middle and some not. I then applied another coat over the lot.

Overall its not too bad looking but I'd rather go for the perfect job. The glass on the sides where the wrinkles and slits are is not structural and doesnt really need to be there - I just glassed right up to the gunwhale because I didnt want to deal with an edge.

I'm thinking the best step from here is to let it cure, then sand hard ignoring the fact that I will be sanding through the glass where the wrinkles are, and then put a generous coat on with fairing filler, then sand again. Is that the right way to go or is there a better way to fix it ?

cheers
Arron

oh bugger
as a pro boat builder. me young bloke did simular. grind the big bumps out and bubbles re glass those areas if you had to grind to bare wood , sand all that you have sheathed just getting rid of the glosss and fairing down your laps and repairs.
then sqeege a filler coat of off epoxy fairing mix and then sand when cured with a torture board of applicable size or macine sander.
a torture boad is good for those bumpy areas, try not to sand back to the glass and if you do, time to fill again and always key up the cured resin/filler before filling again.
to avoid this @#$% again (done it myself when me learnin many moons ago).
i agree with the dry method and use this myself
its hard on vetical surfaces.level.... turn boat surface horiz if possible.
to hold cloth in position,, i use a hand staple gun with s/s staples and just grind the bar off later when i prapare for the 50mm lap of the cloth.
it thicken my resin with silica to stop the resin from draining ,,oh one last tip not to much resin it makes the cloth float to the top and thats where it drapes and wrincles... only just enough to wet it out.
add a filler coat when the lamination has just gone off i.e.soft enough to make a mark with your finger nail and not sticky.
wet on wet they say but its realy wet on green or just set good thing a bout that is no sanding and if you time it tright till the midnight hours you can go right to the final fill coat without sanding but theres alot of vairbles as is with our craft...
graham the shippy

cheers, thanks
Arron

If a hull is sheathed properly the amount of sanding prequired will be a lot less if the glass goes down the wrong way.
Its important to get the glass as close as possible to the substrate wood or what ever. Which basically means you to get as much resin as possible out from in between the ply hull say and the glass on the layup.
The way i always did this was to heavily tape the glass onto the side of the hull where you were going to work with masking tape. Use yr hand to smooth the glass over the side you were working on. The tape should be used to hold the glass as tight as possible.
Then wet the cloth out as carefully as possible and use plenty of resin so you don't pull the glass. Once the area your working on is totally wet. use a squeegy and careful and slowly drag all the resin away.
So example i have a hull upside down and i'm doing 1/2 the bottom first.
lay the cloth from one end to the other transom to bow. Overlap the chine and the keel. Cut the glass along the keel so its maybe going 2-3" onto the other side. Do the same for the chine. Now use yr hand to smooth out any wrinkles. Then tape the glass with masking tape so its stays in place. Then wet out the whole area (i used foam rollers) and then use the squeegie to press the glass hard onto the surface. The squeegie is the same used by surfboard makers and its a piece of rubber say 8" long 1/2" thick and about 3" wide and very flexable. Squeeze the excess resin away from the area your working on. Plenty will squeeze out along the keel and chine. Sometimes i would use tape plastic along the edges to catch the excess resin.
Once that has sat i then use a stanley type blade to trim off the excess cloth. Then take away the tap and off cut glass then clean off any excess runs on resin you may have with acetone of whatever yr using.
You will get a very clean tidy bottom half done. next i would generally let the resin go off a bit and this is a little tricky but i would use a high speed disc sander to carefully blend in the edges of the glass which had been cut with the stanley knife blade. The idea is when you overlap the next stage in glassing you don't want to next layer to go over a ridge. Its not hard and little care to sand with out hitting the plywood. This blend i'm talking about maybe for a distance of say 30mm. Then i would do the same procedure on the other side of the hull.
The idea especially with epoxy is to be very neat. The glass in where your strength is so laying the glass on and trapping resin between the ply and glass serves you no purpose. And if you then sand yr hull perfectly smooth and fair you will certainly sand through the glass if you trap resin.

Howdy,

For small and medium sized projects like we are talking about here, you generally don't need much to hold the glass in place. A few pieces of masking tape - fold one end over so you can grab it with your gloves to remove when you come to that area.

Bigger projects can be a whole different kettle of fish.

Vertical surfaces can be hard to do by themselves, but if the bottom or part of the bottom is being done at the same time (smaller boats), the resin can be pooled there and brought over the side as needed with the squeegee. Fiddly bits around the bottom edge that are still dry after this I finish off with a foam roller.

MIK

Hey guys,
Was just reading through all this and came up with a question.
how do you tackle the stems (front and rear verticles on the boat?)
would you use the 50mm glass tape up the stems and do that, then lay the cloth over the lot? or just use the cloth and trim/fold it to cover the stems?
or is this not really an issue due to the filler epoxy used to fill the joins after stitching the hull.

Milk