What's the best way to fair 1708??

Discussion in 'Fiberglass and Composite Boat Building' started by mongo75, Sep 8, 2008.

  1. mongo75
    Joined: Aug 2007
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    mongo75 Senior Member

    I got a whole bunch of 1708 to glass over the exterior wood on my 25' Luhrs flybridge project. I know some folks would say I shoulda used maybe 8 oz or so, but it's too late for that. I got this stuff (especially because it's strong) and I gotta use it. As you know it is good stuff, but the weave leaves a lot to be desired in the smooth department. Should I lay some 6oz over it, or fill it with a rolled on layer of lightly thickened epoxy or ?? She's getting close to where I need to cover a whole lot of area, so I want to get it right and looking good as easy as possible. ALSO- could someone tell me what the volume of resin to square foot of epoxy should be for a rolled application (no vacuum bag) as I only have about 4 gallons left, and don't want to go overkill buying more.

    Thanks!!
     
  2. mikereed100
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    mikereed100 Junior Member

    Danny,

    I have had good results using epoxy thickened with Q-cells and applied with a sqeegee. It's easy to sand, relatively lightweight and can be done in one coat.

    Your supplier should be able to give you a good idea of how much resin you will need. It will depend somewhat on how much your ply will soak up. I seem to use about 1/2 gal. for 24 square feet of 24oz biax.

    Mike
     
  3. mongo75
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    mongo75 Senior Member

    Thanks Mike, never thought of using a squeegee! That should should fill it good, leave a smooth surface to scuff sand, and that's one less layer of glass I gotta put on.
     
  4. the1much
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    the1much hippie dreams

    awl-fair.hard, but easy to sand,, is what we always use for fairing.
     
  5. the1much
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    the1much hippie dreams

    and you have an hour or so before its too hard to work with
     
  6. bntii
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    bntii Senior Member

    I have lain finishing cloth over with good results.

    Almost any weight will do the trick- I have used 2.5 oz. 6 oz and 9 oz. It holds down the stitching which is a large part of the fairing/grinding load to get a smooth surface. Troweling over with micro-bubbles is still done & leaves a quick to knock down surface. When laying up I roll over with a fairly dry short nap roller and end up with a very smooth surface- still needs the bog but nothing like the grind down the 1708 needs.
     
  7. waikikin
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    waikikin Senior Member

    The best way to fair anything is to turn up on a friday arvo with a slab of cold beer & write the guys doing it & covered in "icing sugar" their checks, tell em they're "all doing very well" & enjoy a couple of cold ones with 'em. Just a matter of the appropriate coin & perspective! Unfortunatly I'm usually one of the "dusty" ones. All the best from Jeff.
     
  8. the1much
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    the1much hippie dreams

    hahaha....i've seen 5 or 6 boats ( built by lobstermen) built that way,,,,sea trials are a little "hairy" but usually fun,,hahah :D
     
  9. alan white
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    alan white Senior Member

    Fairing can be finicky or almost nonexistent. If I were to fair anything I'd fair first and glass with single layers after, but you've gone ahead and used a heavy laminated glass, so you now need to decide what level of perfection you will accept.
    You can make it fair (how bad is it?) by filling with lightweight epoxy/filler and longboarding, followed by sealing with a few coats of epoxy.
    You can leave it alone, just filling the weave with epoxy.

    If you mix some epoxy/lightweight filler and apply with a toothed tile cement trowel, followed by longboarding, you can build up the low areas with less work (avoiding taking off the harder high areas). Then fill the tooth grooves in the low areas with more filler.
    This is probably the quickest route to a smooth hull.

    Alan
     
  10. mongo75
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    mongo75 Senior Member

    I want this thing to look like a production fiberglass boat, so I have to resist the urge to just "get er done" and put the necessary time and effort into it myself. I think the best thing I can do is to take all the different methods everyone mentioned, and have the appropriate tools on hand when I first start to fair- a squeegee, a nice new thin plaster trowel, and mix up some relatively "thin" thickened epoxy using cabosil (or would milled fibers be easier to sand??) and then start pouring and fairing. Once that's dry, I could take a long board to it to see it it still needs more. At least once that first layer is on, it should be pretty easy to see any low spots. What do ya'll think about adding some white pigment (of which I have a bottle) to the fairing slop so any low spots show up better once sanded down?
     
  11. alan white
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    alan white Senior Member

    If you use the toothed trowel rather than a squeegee, you'll use half as much putty on the high spots. You'll easily see the trowel stripes in the low areas, so you fill only those. I've found that you can't easily judge what's high or low as you sqeegee and so you tend to waste epoxy. The toothed trowel method simply lays down a low-waste coat and once long-boarded it gives you a much better idea of where to fill. They make trowels in every size tooth, so a second going-over with an even smaller tooth will onl;y need minor filling after long-boarding lightly.
    Then you'll have your production quality job.

    A.
     
  12. mongo75
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    mongo75 Senior Member

    Alan, I'm not sure I entirely understand how to go about doing this with a toothed trowel- do I run a toothed layer of thick epoxy on the 1708, and then knock it down, or just let the ridges dry and then long board it? What I got in my head is the idea of having a bunch of hard ridges on my glass that I have to sand down. Please elaborate if you can to make it easier on this bug dumb animal.
     
  13. Meanz Beanz
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    Meanz Beanz Boom Doom Gloom Boom

    Yes... that way you get closer to fair with less filler (also less effort + a bit more efficent)... then you have a guide to fill the groves.

    Cheers
    MBz
     
  14. the1much
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    the1much hippie dreams

    i gotta try 1 of those toothed trowels,, i use 12' 24' knives, and if needed bigger then that i use a piece of batten,,hehe :D
     

  15. alan white
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    alan white Senior Member

    Meanbeans has got it right. The toothed trowel lays down filler to an exact depth everywhere. Lay it on just exactly as if you were going to lay tile.
    Running a fairing batten across the 1708 bneforehand should tell you the size trowel (and working angle). Just match the tooth-space of the trowel you use to the deepest gap you find.
    Once cured, longboard FIRST and then fill the ridges in. You'll waste little epoxy the second go-round since you now have an even top surface.

    A.
     
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