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Thread: Best Way to Lay Glass on Lisa B Good

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    Default Best Way to Lay Glass on Lisa B Good

    Hi, I am looking for the best way to lay the glass on the bottom hull of Lisa B Good. It is barge type plywood hull 7.5' x 16' and I have 10oz x 50" glass. I am a new to this but my thinking is since boat is 90" wide I would lay down 2 strips lengthwise overlapping one inch on centerline with 4.5" to fold over each side. I was going to put blue tape at about 4" for nice crisp edge when trimmed. Is there something I should do different? I just want to be as efficient with the glass/epoxy as I can and certainly don't want to ruin anything. I can post a picture of the hull when I get home. Any advice greatly appreciated. Thanks.

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    Default Re: Best Way to Lay Glass on Lisa B Good

    The cloth is very easily distorted, which is a good thing when covering compound curves. For precise fitting on large, straight flat surfaces, it can be difficult to keep straight. You might find a 1" overlap down the center line, which is 45 wet sticky inches away, is more of a problem than you had anticipated. It would be easier to overlap by 2-3 inches, with 4 - 3.5 inches of fold over the side.

    Make sure you have a generous radius on the chines. The cloth will want to lift and form a bubble if the corners are too sharp.

    Cut the cloth to length plus 6 inches or so extra. Roll the cloth as straight and tight as you can on a tube so you can unroll it neatly onto the hull. 2-3" diameter tubes are good for ease of rolling and handling.

    Use slow hardener unless you have lots of recent experience and can work extremely fast.

    Use a non-blushing resin. (There are strong opinions about blush and ease of washing. This is my opinion. T.B. thinks I am daft for thinking this. Who knows, he may have a point. There is an extreme level of brand loyalty.)

    Do one side at a time. Wet the surface before you unroll the cloth. Keep it tight as you unroll to minimize the amount of bubbles to work out. Starting at the center, work the air pockets from the center towards the ends. If you are new to this, let the resin cure hard enough so you don't have to reach across 4' of goo before starting on the other side.

    If you let one side cure before glassing the other side: If it goes more than overnight you may have to wash off blush and let it dry. The selvage edge will make a lump that might give you problems with air pockets at the edge of the lap. Slice off any large lumps with a chisel or cheap plane. I would mix up some thickened epoxy and cover the edge, then apply the cloth while the filled epoxy is still wet. It will blend and you don't normally care about appearance (bright work) on the bottom.

    -Dave
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    Default Re: Best Way to Lay Glass on Lisa B Good

    Thanks for taking time for detailed response. I do have slow hardener and I am using Duckworks Miapoxy. My radius on chines is maybe 3/8"-1/2"(?). So, if I understand correctly, i wet half the hull lengthwise then carefully roll out pre-cut piece tightly onto that overlapping middle couple inches then squeegee towards ends. Do I get started on other side right after?or do I need to let cure a little bit before i overlap middle 2", again? I appreciate your help. Like I said I'm new to this, and while i trust my wood skills, I am real nervous about my glassing skills...or lack of, and would hate to waste product. I hopefully .thought the rest thru pretty good. I got tyvek bibs, latex gloves, respirator and pumps for mixing. should be good but still..

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    Default Re: Best Way to Lay Glass on Lisa B Good

    If you pre-cut your fiberglass, do it pretty generously. Things tend to move and sometimes change shape a bit as you are saturating the glass and you don't want to find yourself coming up short in places. If need be, you can even trim fiberglass to size while the resin is still wet, right after saturation with a pair of good scissors. Vinegar will remove the wet resin from the scissors. It will also remove it from other tools, fingers, etc. so it is worth buying a bottle of it to have on hand.

    In my opinion, the best piece of "equipment" you can have for a big glassing job is an assistant to mix you a steady stream of small-ish, properly measured and properly stirred batches of resin. This job is absolutely critical to the project, and if you are the person who will be fitting the cloth and applying the resin to it you already have enough on your plate. Get somebody else who you trust to mix resin without all the distractions. A small error because your mind was elsewhere as you rushed to mix the next batch can make for an unbelievable mess to try to sort out later.

    Also understand the bias weave scenario. As your cloth wraps over the chine you will find that it resists doing so and staying down tightly on the wood much more in some places than others. If, due to the hull's shape, the cloth crosses the chine on a bias (diagonal to the cloth weave) you will find that it drapes easier and makes the chine bend much easier than in spots where the cloth weave is pretty much square to the chine. On a bias, you can wrap fiberglass around an amazingly sharp curve, but square to the weave, it often wants to pop back up after you stick it down, again and again. Covering the bottom of a boat and wrapping over the chine you will usually get some of both scenarios. It is possible to eventually get those stubborn spots to stick down and stay down, but you need to be there at the proper time in the hardening process to push them down for the final time and do so. When folding just a few inches of glass cloth over an edge like a chine to stick it down and having problems, it often works better if you trim the woven selvedge edge off of the cloth. This frees up the weave so the yarns can move a bit on each other and conform to the shape better.

    It can certainly be boring sitting around watching epoxy harden, just to make sure nothing weird happens, but it is usually worth keeping a pretty close eye on it until it has stiffened up enough that nothing can move.

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    Default Re: Best Way to Lay Glass on Lisa B Good

    Another approach would be to do the chines with 2 layers of 6 oz. by 8" bias weave tape, feather the inboard edge, then lay the 10 oz. just flush with the chine, first one side, then once it's cured and you've feathered the inboard edge, the other side with all of the overlap down the center.

    That would save you a lot of stress trying to keep that 10 oz. cloth laying flat and tight at the chine. You could do it alone that way, starting at one end and working your way pushing/pulling out the slack as you go to the other.

    I have found it best when starting in the middle to work a bit towards one end then a bit towards the other, back and forth until it's done. That way I don't risk having one end getting tacky before I get back to it, I'm always applying wet to wet. If you allow one area to get tacky before you're finished then try to blend into it it can go pretty badly for you, with permanent big bubbles, and unwetted cloth.

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    Default Re: Best Way to Lay Glass on Lisa B Good

    HPIM5702.jpg
    This is what i am working with.
    So, it sounds like if I'm there at the right moment when it is tacky enough I should be maybe ok getting glass to stick around chines? I can say with near certainty that i will be there every moment. The woven selvedge is that like a hem on the edge that should be trimmed to relax the fibers? Thanks again for taking time responding to this. I have tried reading up on process before hand but seems everybody little different, so the more i learn the more confused i become.

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    Default Re: Best Way to Lay Glass on Lisa B Good

    See the edge on this? It's thicker than the rest of the tape.


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    Default Re: Best Way to Lay Glass on Lisa B Good

    Yes, it's the woven edge. If the cloth is cooperating and laying down tight the edge is fine, but if the cloth is putting up a fight, trimming off the edge can help relax it.

    Looking at your photo, if I was going to glass that boat I really think I would probably do the bottom right up to about 1/4"-1/2" from the chines and then overlap it and wrap the chines with the narrow stuff or bias-cut strips of cloth, like what Gib suggested in post #5. It just seems like a really big expanse to keep an eye on all at once if you are also having to watch the edges and you haven't had much glassing practice. That way, you could stick the big area down, concentrate on doing a really good squeegee job to get it down tight to the wood and evenly saturated, and then worry about wrapping the chines in its own step later. In the grand scheme of things, I think it just makes the whole fiberglassing process a lot easier. The filler coats will eliminate the vast majority of the step-down between layers, so final clean up and sanding won't really be any more difficult.

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    Default Re: Best Way to Lay Glass on Lisa B Good

    And it really really does help to fair those thick edges before overlapping anything on to them. If you don't you will get a nice straight big long beautiful bubble for the full length when the thick edge holds the next layer up off of the substrate. Don't doubt this. It only takes a couple of minutes with a belt sander and 40 grit. Keep the belt from clogging with a big crepe eraser and a wire brush. Use them often so the sanding dust doesn't get baked in, and do use bias woven tape. Two layers of the lighter stuff will be easier.

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    Default Re: Best Way to Lay Glass on Lisa B Good

    ok. I am going to get some bias woven tape and do as you suggest. It sounds like best assurance to get good wrap around chines. The edges were routered(3/8). sanded and faring compound along most of edge...is this what you mean by 'fair the edges' should radius be greater and edge sealed completely?

    So, couple more total beginner questions, first I do one side of my hull overlapping middle and staying 1/4 to 1/2 inch from edge. next I do other side overlapping middle and staying back from that edge...do I do this side directly after 1st side? or does it need to tack-up or cure 1st? Lastly, I do my bias weave tape on 1st side I did then other...Do I have to wait at all from doing bottom or can i tape right away. And, do I do sides right away or should I stop at the tape then finish/paint bottom then flipover since sides are not complete without top deck?
    Thanks greatly for your help and guidance.

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    Default Re: Best Way to Lay Glass on Lisa B Good

    And it really really does help to fair those thick edges before overlapping anything on to them. If you don't you will get a nice straight big long beautiful bubble for the full length when the thick edge holds the next layer up off of the substrate.
    I've already got on thread going on about this very topic over in Building/Repair, but this is where I strongly disagree. Fiberglass, when properly applied and squeegeed down simply is not that thick. There is no reason that there should be a bubble along that edge and assuming that you will be filling the cloth weave to arrive at a smooth hull, the filler will take care of the minor step-down between layers. Six-ounce, ten-ounce- it doesn't matter. It is absolutely possible (as well as possibly stronger) to build a great boat and a smooth, fair hull without trying to taper out fiberglass layers with a sander or scraper. Taper out the filler coats. That's what they are there for!

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    Default Re: Best Way to Lay Glass on Lisa B Good

    Quote Originally Posted by apesclan View Post
    ok. I am going to get some bias woven tape and do as you suggest. It sounds like best assurance to get good wrap around chines. The edges were routered(3/8). Sanded and faring compound along most of edge...is this what you mean by 'fair the edges' should radius be greater and edge sealed completely?

    With heavy cloth like you're going to use the selvedged edge is quite thick, so if you overlap onto it the overlapping layer tends to lift off of the substrate along that edge. Also, when you sand that long "lump" you will go right through the overlapping layer creating a break in the continuity of the glass.you can avoid that by feathering that edge before overlapping it.

    3/8 radius will work well with 2 layers of 6 oz. Bias weave.

    So, couple more total beginner questions, first i do one side of my hull overlapping middle and staying 1/4 to 1/2 inch from edge. Next i do other side overlapping middle and staying back from that edge...do i do this side directly after 1st side? Or does it need to tack-up or cure 1st?

    If you want to feather the edge you'll be overlapping you will need to wait for it to cure first. 24 hours will be enough for that if you wear a mask, any less than a week though and you'll be creating toxic dust. If you wait until it's still just barely tacky you can cut off the selvedged edge with a razor knife and pull it up, but you need to be careful not to pull up any of the rest of the cloth. With the bulk of that edge removed you may be able to overlap without getting the bridging, but i would wait until next day and sand it.

    Lastly, i do my bias weave tape on 1st side i did then other...do i have to wait at all from doing bottom or can i tape right away.

    Same as the overlap down the middle of the bottom.

    And, do i do sides right away or should i stop at the tape then finish/paint bottom then flipover since sides are not complete without top deck?
    Thanks greatly for your help and guidance.
    i think you'll find it easier to do the sides at the same time as the bottom, feather the edges at the chine and clean up the radius then do the bias weave.

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    Default Re: Best Way to Lay Glass on Lisa B Good

    Quote Originally Posted by Gib Etheridge View Post
    And it really really does help to fair those thick edges before overlapping anything on to them. If you don't you will get a nice straight big long beautiful bubble for the full length when the thick edge holds the next layer up off of the substrate. Don't doubt this. It only takes a couple of minutes with a belt sander and 40 grit. Keep the belt from clogging with a big crepe eraser and a wire brush. Use them often so the sanding dust doesn't get baked in, and do use bias woven tape. Two layers of the lighter stuff will be easier.
    Quote Originally Posted by Todd Bradshaw View Post
    I've already got on thread going on about this very topic over in Building/Repair, but this is where I strongly disagree. Fiberglass, when properly applied and squeegeed down simply is not that thick. There is no reason that there should be a bubble along that edge and assuming that you will be filling the cloth weave to arrive at a smooth hull, the filler will take care of the minor step-down between layers. Six-ounce, ten-ounce- it doesn't matter. It is absolutely possible (as well as possibly stronger) to build a great boat and a smooth, fair hull without trying to taper out fiberglass layers with a sander or scraper. Taper out the filler coats. That's what they are there for!
    While you can take almost everything either Todd or Gib has to say to the bank, this is one of those rare instances where one of them is wrong. For a certain value of wrong. I would say that Todd misunderstood and Gib could have described it better. In this case, Gib was talking about a sharp corner when he said 'thick edges', which is unthinkable to Todd. As Todd said, properly applied, i.e. properly prepared and applied. I don't think Todd can easily wrap his head around something as dumb as glassing a sharp corner.

    Last night I slit and filled the last 4" long bubble on a corner that had almost, but not quite enough radius. In 175' of nearly right angle corners there must have been 5 bubbles, all in the 3-5" long and 1/2-3/4 inch wide range that had to be filled or cut away and re-glassed. 6 ounce glass (from the place Todd correctly said that he would not buy the glass in another thread) and a 1/4 inch radius. We had to close up shop around 10:00, so waiting until midnight to squeeze down the bubbles wasn't an option. This is a pair of 20' pontoons for a catamaran.
    Management is the art of counting beans. Leadership is the art of making every being count. --Joe Finch

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    Default Re: Best Way to Lay Glass on Lisa B Good

    Im not sure that your interpretation of what Gib meant by thick edges is accurate. Maybe he will explain it for us.

    I don't think Todd can easily wrap his head around something as dumb as glassing a sharp corner.
    I don't know if I need to wrap my head around it, but I can do it if needed. This is 7.5 oz. cloth, two layers thick and wrapped around a paddle tip about 3/16" thick, which makes for some pretty sharp corners - no cuts, no seams, just two layers of cloth.



    As to step-downs between layers, consider modern fiberglass canoe construction for the last 40-50 years, where the layup will be about three times as thick on the boat's bottom as it is up near the gunwale, with all sorts of extra little reinforcing bits and layers of fiberglass inside the laminate. Now guess how much feathering is done along the edges of all those pieces before the next layer goes on. If you guessed zero, you guessed right. In a well done layup, there are no bubbles along those edges, and it's not like you need to be the world's best fiberglasser to achieve that. It's just a matter of working carefully and attention to detail.

    I see the OP's boat as one big glassing project along with a couple tedious strips along the chines. I just think a glassing newbie has a much better chance of being able to do a good job of it by splitting the work into a couple of steps.

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    Default Re: Best Way to Lay Glass on Lisa B Good

    What I mean by thick edges Todd is the selvedged edges. I have had it happen that with 10 and 12 oz. cloth the edges hold the next overlapping layer up away from the substrate . I squish it back down and a few minutes later it's started to lift again. For me it's been easier to just feather it before overlapping another layer and have it over with. As you advise, "It's just a matter of working carefully and attention to detail."

    Also, if one doesn't feather those edges before applying the overlapping layer it takes a lot of resin to fill that and the surrounding area enough that when sanding fair the overlapping layer doesn't get sanded through.

    I don't think it's fair to compare fiberglass canoes to glassing over ply. Those guys don't care too much how much resin it takes to fill everything.

    I suppose I'm being nit picking, it won't really matter that much on the bottom of a scow type hull. I can be a bit obsessive, although I've never gotten the fine finish that you do.

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    Default Re: Best Way to Lay Glass on Lisa B Good

    I've never had a problem with selvedge edges, though in most cases when working with big hunks of fiberglass cloth or roving, I usually trim them off as it can allow better draping and easier conforming to odd shapes. The only type that gave me fits was one type of selvedge edge which has little fringy strands about 1/2" long hanging off the edge. I don't know what the technical term for that type of selvedge is, but I hate that stuff.

    I don't think it's fair to compare fiberglass canoes to glassing over ply. Those guys don't care too much how much resin it takes to fill everything.
    You don't think composite canoe builders and/or users are concerned about excess resin weight - either in terms of just portage weight or strength in terms of glass to resin ratios? I would venture that they are probably paying a hell of a lot more attention to it than folks glassing plywood boats are.

    At some point though, I think everybody who does fiberglassing should wet out two or three layers of cloth on a sheet of waxed paper, squeegee it down to a good cloth to resin ratio and let it harden. After that, peel it off and witness just how thin it actually is. A step down from two layers to one layer, even with a selvedge edge is a very small step.

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    Default Re: Best Way to Lay Glass on Lisa B Good

    can i do the bias weave tape on edges as soon as my bottom glass and side glass are done wetted or do i need to allow that to tack up first? and, will one layer of the 6oz tape be good or will that need another layer? thanks.

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    Default Re: Best Way to Lay Glass on Lisa B Good

    Either way is possible, though it is often better to wait until the bottom layer is stiff enough that you won't disturb it while adding the top one(s). A single layer of six-ounce doesn't give very much abrasion resistance, so two would be tougher. It is best to stagger their edges to make a smoother transition - either using two different widths, or by offsetting them a bit.

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