bare fiberglass hull - how to proceed?

Discussion in 'Fiberglass and Composite Boat Building' started by willyd, Mar 31, 2008.

  1. willyd
    Joined: Mar 2008
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    Location: Commonwealth of Virginia

    willyd Junior Member

    I'm looking for advice on a boat project. I have acquired a trailered 25' sailboat which the previous owner ground off the gelcoat and outer layer of mat on the entire hull below the waterline. I have found all sorts of advice on how to rebuild the hull with epoxy, but I'm looking for a cheaper solution.

    Would it be OK to recoat the hull to replace the ground-away material with polyester resin (e.g., Evercoat Premium Marine Resin), then sand smooth and fair, or should I use a filler, such as Evercoat Rage or Evercoat Marine filler?

    Also, bottom paint manufacturers like Interlux and Pettit have directions for applying bottom paint to bare fiberglass - this implies I don't need to worry about gelcoat, correct?

    So, in my search for the cheapest way to get this boat back in the water - a layer or three of marine resin, followed by a few coats of, say, Pettit Unepoxy bottom paint - or would this be pure folly?

    Thanks for any advice!
     
  2. the1much
    Joined: Jul 2007
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    Location: maine

    the1much hippie dreams

    i'll probably be shot at,,,but,,heh,,if ALL they ground off was the first mat layer,,i would ( thinking of cheap AND safe) put 2 layers of matt (after grinding for you "mechanical bond") then this may sound like your spending more,,but you wont in 6 months,,anywayz,,then gel-coat the area,,,then apply your bottom paint.
    the "mat" they ground off isnt there for "strength" its for the heavier layers to "hang" on to,,and so the fabric doesnt "print through" onto your gel.
    i NEVER would recommend that anyone "just put on bottom paint" the crap starts wearing off the VERY minute you stick it in the water,,very LITTLE "water proofing",,,and when they say its a "barrier" paint,,,they just mean a "barrier" from green gunk and barnacles,,hehe ;)
    o.k.,,,thats my 1.6 cents worth.
    welcome to the forum,,and sorry i was the first ya met hehe ;)
     
  3. Landlubber
    Joined: Jun 2007
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    Landlubber Senior Member

    willyd,

    May I suggest that you start with a layer of 300 gsm csm, wet out and followed by a layer of 600gsm woven rovings, this will replace what was ground off ( one would assume it was because it was osmosiced).
    After doing this, in the same day if possible, you then let it set (at least overnight) and then get a nice 8" random sander and lightly sand flat(use say 120 grit alumunium oxide frecut paper), smoothing out the lumps only really.

    Then with a solventless epoxy resin, roll a nice wet layer over the whole bottom, repeat this process and then leave for a week. resand then.

    Apply another coat of solventless epoxy resin.

    Then , using an epoxy primer/fairing compound. roll another two coats onto the abraded surface, allow to set for at least a day, and then sand the whole bottom fair.

    Reapply another primer coat of epoxy primer, then follow up the same day with your favourite antifouling. Another coat the next day and she is ready to launch.

    Have fun, a 25ft boat is a nice size to work on, you never get tired of sanding as there is not much bottom on her.
     
  4. PAR
    Joined: Nov 2003
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    Location: Eustis, FL

    PAR Yacht Designer/Builder

    Landlubber has it right, you have to seal up the mat or other exposed fabrics, which will not resist moisture working it's way into the matrix.

    Fair it up with whatever fabric you like, then barrier coat the bottom with straight, unthickened epoxy or gel coat (not paint). Apply enough coats (minimum of three if epoxy) to insure it'll be water tight. Now you're ready for paint prep.
     
  5. willyd
    Joined: Mar 2008
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    Location: Commonwealth of Virginia

    willyd Junior Member

    filler?

    What's wrong with replacing the lost mat - a cosmetic layer - with filler? Is it a flexibility issue since I'd have to fill such a large area? The stigma of having a boat that's basically all bondo?
     

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  6. the1much
    Joined: Jul 2007
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    the1much hippie dreams

    it'll crack in a year of flexing,,and if your cost is to be watched,, filler will be more $ and WAY more work.everyone else will give ya the"specs" i imagine
    hehe ;)
     
  7. PAR
    Joined: Nov 2003
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    Location: Eustis, FL

    PAR Yacht Designer/Builder

  8. willyd
    Joined: Mar 2008
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    Location: Commonwealth of Virginia

    willyd Junior Member

    Why two layers of mat? Wouldn't the original lay up have had just one?
     
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  9. the1much
    Joined: Jul 2007
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    Location: maine

    the1much hippie dreams

    you need to put more on then you think was there,,,that way everything can be faired,,is NO way someone ground JUS 1 layer of mat,,so ya need more,,then fair to right thickness ;)
     
  10. willyd
    Joined: Mar 2008
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    willyd Junior Member

    the1much - you're in Texas, so is my boat: so can I use your driveway to do this repair? That way I can just pound on the screen door whenever I've got a question instead of sending innumerable postings.
     
  11. the1much
    Joined: Jul 2007
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    Location: maine

    the1much hippie dreams

    head over,,but driveway rental is $2.99 an hour hehe ;)
    and info is free after a week rental ;)
     
  12. ratrace2
    Joined: Dec 2007
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    ratrace2 Senior Member

    Yea, don't fight the "much", just do what he says...........heheh
     
  13. mongo75
    Joined: Aug 2007
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    Location: Orange County California

    mongo75 Senior Member

    Two layers of matt w/epoxy, not poly or vinyl resin, will do it right. You could do it cheap and quick, but you're pretty much destroying th hull in the long run. You pick your choice...
     
  14. willyd
    Joined: Mar 2008
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    Location: Commonwealth of Virginia

    willyd Junior Member

    quantities

    Thanks to everyone for their input. I've been looking at various sources on the net to determine what quantities I'll need of materials. My boat is 25' X 8', which X .85 gives 170 square feet of hull surface, according to the formulas used for bottom paint. If I use 170 square feet of 1.5 oz. mat, with 4 ounces of resin per square foot (according to fiberglasssite), that yields 680 ounces, divided by 150 oz./gal, gives me 4.5 gallons. For the first layer.

    My question: how much more resin should I factor in for the second layer?

    I'm assuming that the second layer will be laid up on top of the first, while the resin is still wet.
     

  15. the1much
    Joined: Jul 2007
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    Location: maine

    the1much hippie dreams

    i dont know how ta do all that math stuff,,,,but,,,if your math says get 4 1/2 gallons,,,,then get 7 ,,,trust me,,,,you'll never use all ya resin in every bucket you make,,,then theres the "****,,i jus stepped in the resin bucket",,,i'll let these other math knowledgeable dudes tell ya the rest hehe ;)
     
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