Fiberglass Overlap and Clear Finish

Discussion in 'Wooden Boat Building and Restoration' started by DMAN1968, Aug 6, 2007.

  1. DMAN1968
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    DMAN1968 Junior Member

    Hello All...Long time viewer, first time posting,

    My question is...When you want a clear finish to show the wood sides on a boat and you want to use light weight fiberglass cloth on it, How do you handle the edges that will overlap? This will obviously give you a line where the fiberglass thickness is doubled...How is that made to be invisible?

    Thanks in advance for your time.
     
  2. DMAN1968
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    DMAN1968 Junior Member

    Thanks for the quick response. I did a little research and have found some references to aluminum/nylon bubble rollers. Is that what you are referring to? Also, would that work for 6 ounce cloth?

    Thanks Again.
     
  3. PAR
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    PAR Yacht Designer/Builder

    The common trick, is to intentional place a healthy overlap and wait until the green stage of the curing process (still quite soft, but tack free or near so), when it's razored through. Use a straight edge (it'll hold the fabric down), make the cut through both layers of cloth, peel off the upper layer (it'll be a strip), then lift the other layer and peel out the second piece. Then re-wet out the area (you have to lift open the seam) and push down the fabric, which should align perfectly, without a bulge. This doesn't hurt the bond, because it's in the green stage and you'll be creating a chemical linkage (fresh goo over green goo) when you apply more epoxy to re-stick the cleaned up seam.

    6 ounce cloth will not be completely invisible. Up close (within a few feet) you be able to see the weave of the fabric if the light hits it just right. 4 ounce or lighter for truly invisible cloth sheathings.
     
  4. fiberglass jack
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    fiberglass jack Senior Member

    and mind your fingers I got a nasty scar on my index finger, from doing what Par said
     
  5. DMAN1968
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    DMAN1968 Junior Member

    Thank you all for the information. I mainly was thinking ahead on a boat project of mine. I am trying to figure out the best way to protect the veneer wood sides of a plywood runabout I'm working on while at the same time being able to see it.

    I do not intend any rough service out of it...but want to keep it as safe and good looking as possible.

    Thanks again.
     
  6. PAR
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    PAR Yacht Designer/Builder

    A few coats of unthickened epoxy alone, will not provide any abrasion resistance at all. You have to have some sort of reinfrocement for this type of protection. Epoxy alone (if the piece is totally encapsulated) will lock down moisture content and stabilize the wood, but not much else without reinforcement. Anything that gets goo'd down with the epoxy (fabrics, wood flour, micro balloons, etc.) can be considered reinforcement.

    4 ounce cloth doesn't offer much protection, but much more then painted or epoxy coated surfaces. Don't use Douglas fur plywood, if you want a bright finish. You can't sand it smooth and the grain is usually quite wild, from being rotary cutting. Mercanti, okoume, sapele, mahogany or other tight grained species can look okay if rotary cut, much better if sliced.

    Most would like to think they will not see rough service, but rough landings on the trailer, docks, piles, things in the water, etc., will leave their marks (literally) on the hull shell. I usually level the surface pretty darn smooth with epoxy (several coats) before applying cloth. The smoother the surface it's applied to, the easier it is sheath and fill the weave and have sweet looking results.

    Jack, I cut the tips off two of my fingers working out a seam. They had flat spots on the ends for about 6 months.
     
  7. eponodyne
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    eponodyne Senior Member

    I'm willing to bet the common razor knife is responsible for more trips to the emergency room than all other tools combined.
     
  8. PAR
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    PAR Yacht Designer/Builder

    One of my favorite tools is the common single edge razor blade. I use them nearly every day, honing down epoxy drips, scoring, fine scraping all sorts of things. I have better control with the naked blade - holders are for sissies . . .
     
  9. fiberglass jack
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    fiberglass jack Senior Member

    Par proballycould trim the glass using his feet who needs hand
     
  10. PAR
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    PAR Yacht Designer/Builder

    I'm not real good with my feet, but I have been known to use my ever enlarging bald spot, as a squeegee on overhead work.

    Un-reinforced epoxy alone will not prevent checks or other internal stresses from apearing on the surface (over time) and has no abrasion resistance. It's not really debatable with the testing and research performed in the last 30 years.
     
  11. fiberglass jack
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    fiberglass jack Senior Member

    just coating the wood with epoxy is only a bandaid, you should use a cloth to reinforce, of course you could only use epoxy but it will turn around and bite u in the arse down the road, its like taking a dump and not wiping your butt, posable but not advised
     
  12. PAR
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    PAR Yacht Designer/Builder

    There are a lot of "retro" builders showing up, particularly in the last 15 years. Spencer uses good materials, good encapsulation techniques and doesn't really need to care how long their products last after they've shipped. There are plenty of builders like this. Look at all the production craft that still use poor techniques and materials. These boats are considered "disposable", because they serve their owner for ten years and then sit in a carport for another ten, before being hauled off to a land fill.

    Coat a piece of good marine grade Douglas fur plywood, with as many coats of unthickened epoxy as you want, then let it sit for a while, out of the direct sun so it doesn't break down from UV exposure. After a few months the internal stresses in the very stable plywood will come to the surface, breach the un-reinforced coating and now you don't have total encapsulation, just a plastic coating over most of the surface. This permits moisture gain and the wood begins to move. The movement cycling, will force more breaches and it's a quick down hill slide after that.

    For what it's worth, I've repaired a few Spencer's already. They do nice work, but the owners of these craft hang them in slings, sometimes covered, most, not and the coating take a beating. They pay big money for these girls, take minimum care of them and then want a "freshening up" a week before the next boat show they'd like to attend. I'm like a hooker, outside a GM assembly plant on payday, with a minivan, for a weeks before these shows, every year. Many of my clients now understand the responsibility of ownership of these retro classics, but often they just don't care, "that's what the money is for . . ." is the attitude. Guess what happens to the stainless fasteners Spencer uses, when these girls live in salt water. In fairness, they do offer bronze fasteners too, but it's not pushed, which it should be, especially considering their prices.
     
  13. cudashark
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    cudashark Senior Member

    Hi Par,

    And please pardon me for hijacking this thread. I am building a 33' cruser of mahogany. The construction is frame with a 4 ply mahogany veneer layup over the frame. I plan the keep it bright from the chine up and plan to use a 6oz glass as an abraison resistor. In your opinion would it be wise to coat the mahogany with 2 or 3 coats of epoxy before the cloth? or The cloth in the first layer w/2 -3 coats of epoxy?

    Also would you sand any prior coats to say 220 grit before applying the glass layer?

    And one more thing, From the picture below ( just starting the battening process) I plan to epoxy the entire inside of the boat with several coats of epoxy. Besides any fillets and connection points of stress; would you also glass the frames and such?

    Thanks in advance. I enjoy and appriciate your post on many subjects.

    Ray

    PS I'm just south of you in Hobe Sound FL, feel free to stop in if your get down this way.
     

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  14. PAR
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    PAR Yacht Designer/Builder

    Ray, since you've already assembled your frames, you will not get epoxy on every square inch of material. This means you can't encapsulate, which is the point of using epoxy. Moisture gain in the joints, at gussets, floors, etc. will cause difficulties later in the boat's life, if you epoxy the currently assembled pieces.

    I would repeatedly soak the frame and structural members you have built, with several coats of 50% boiled linseed oil and 50% spirits. It will take some time (weeks) for this to dry, then apply the same mixture, but with a few ounces of Japan drier added (per each half gallon of oil mixture) to seal down the last coat. Varnish, polyurethane or paint over this after this is dry. This is much like what the original builders would have done and a well proven method. This oil mixture comes in a variety of formulations, some with less spirits, others more, still others progressively diminishing amounts of thinner as additional coats are applied (my normal routine). This seals the wood well, permits moisture cycling, with little harm. Some formulations (hi Max) include pesticides or wood preventives, which I don't include, unless the species used is prone.

    The best way to epoxy the planking, with a bright finish in mind is a one shot deal. By this I mean you'll be applying goo, fabric and more goo, all during the "green" stage of the epoxy curing process, which provides the best bond. Apply a coat of unthickened goo to the planking, wait until it's no longer tacky then another coat. Visibility check every square inch for dull areas and if some show, then another coat of unthickened epoxy. Keep coating until the whole surface, bar none is shinny, meaning it will suck in no more. Again, wait until the goo loses its tack (or nearly so) then apply you cloth (6 ounce will just barely be visible, but 4 ounce will not) and wet out. Don't try to fill the weave, just get good contact and wet out. Wait until the tack free stage (anywhere from a half hour to a few hours, depending on brand of goo and conditions) and then fill the weave with unthickened goo. Do it again if necessary to fill the weave.

    At this point, you're pretty much married to the surface you've created. Let it cure good for a few days so it gets good and hard, then wet sand your brains out, until you're satisfied with the fairness of the hull. If you had a fair hull when you started, use the green on green method, got good wetout and filled the weave with the minimum of goo, you'll have a nice looking surface, requiring some wet sanding and varnish or polyurethane. If you permitted runs, bubbles and unfair areas in the wood to remain when you started the goo job, they'll show in the final product, mostly as blotchy or milky areas.

    The day you pick for this task will be a long one. You'll be chasing drips, sags runs and other issues all day. Pick one that will have a favorable climate, if working without control over the conditions. A helper, mixing goo will speed things up. work quickly, but not sloppily and have a scraper at the ready, to get the runs, drips and sags, before they become issues.

    If you've screwed up the surface in some way and didn't catch it, you'll have to wait until it's fully cured to fix it with sanding and more goo.

    The above described, is the chemical bonding technique and will provide the strongest attachment, of the layers of goo and cloth. You can wait until a full cure, sand and do the next step, but the bond isn't as good.

    You can encapsulate pieces of the boat you haven't yet installed with epoxy and it will help preserve these pieces. Remember, each and every square inch of surface, fastener holes, notches, etc., must be coated or you're kidding yourself.
     

  15. cudashark
    Joined: Jul 2006
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    cudashark Senior Member

    Hi Par

    That was just a test fit. It has not been perminetly put togeather.

    Also it has been comprised if laminated mahogany.
     

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