Gelcoat

Discussion in 'Fiberglass and Composite Boat Building' started by chandler, Jun 4, 2010.

  1. chandler
    Joined: Mar 2004
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    chandler Senior Member

    What exactly is gelcoat?
     
  2. gonzo
    Joined: Aug 2002
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    gonzo Senior Member

    It is a resin, usually with a lot of load to increase viscosity and pigment. It takes the place of paint.
     
  3. apex1

    apex1 Guest

    May I add:

    it is a useless ****, incorporated by the industry (us) to make the entire deal easier. Because a good layed GRP hull would not need it (it is brittle and not watertight), but saves centuries of manhours in producing mass products, looking nice.
    And that is what the market likes, shiny crap.

    Regards
    Richard
     
  4. tunnels

    tunnels Previous Member

    Manufactured from a resin base with pigment for colour , promoters to make it go hard when its catalysed , and fixatrophica gents to thicken and allow it to hold inplace on a vertical surface till it goes hard and if the correct Catalyst is used at the right ratio per kg it can be quite trouble free for many years of service .
    Like all things associated with resins theres a list of gelcoats as long as you arm for all kinds of applications and uses .dark colors are more prone to breaking down in the sun and uv than white and pastel shades . :D
    Almost forgot there are differant hardnesses as well !,some can be very hard right through the range to almost rubbery ! each product has its own use and application . Want to know more befriend a industrial chemist !!
     
  5. waikikin
    Joined: Jan 2006
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    waikikin Senior Member

    Chandler, Its a fantastic product, at a low cost per meter square basis on a contact molded composite stucture it gives a beautiful, durable & repairable surface. All the best from Jeff.
     
    Last edited: Jun 6, 2010
    1 person likes this.
  6. tunnels

    tunnels Previous Member

    Theres nothing wrong with shiny ****! as long as it looks good and its the right colored crap !!
    No its not waterproof like i used to think it was when i started to work with it But its up to the person operating the spray equipment and the manufacture to get the best from it . Not all catalysts react the same , when it comes to Gel coats take advice from the chemist that made that fancy **** and use what he recomends . To much catalyst you have porosity problems forever more , to little and its soft and chalky and breaks down quickly , to thin and you will be able to see the back up layers of glass , to thick and it cracks and crazes and can have color separation where the pigment trys to separate from the semi clear resin base it is suspended in , and a dozen other things as well .
    Did you get the point i am making ??
    Use the right catalyst ,
    Use the right catalyst ratio ,
    Use the right amount for the given area = (the thickness),
    Back up the gelcoat with a resin rich first csm glass layer using Vinylester resin that is rolled and 99% bubble free
    Now is that to much to ask from some one thats an expert and done the job a million times ??
    Its all crap if you want it to be, even paint can be crap , But it looks nice so its nice crap or **** or whatever !!
    :D
     
  7. chandler
    Joined: Mar 2004
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    chandler Senior Member

    Thanks for all the info.
    The reason I asked is because I am planning on purchasing a 82 freeddom ck.
    The survey showed alot of saturation of the core.
    I'm thinking the best way to fix this may be to take off the gelcoat, the glass and core and cold mold the hull, glass it and paint it with a high quality compatible paint.
    I'm a wood boat guy. Does this sound feasible?
    Will epoxy hold the cold molded new core to the existing, I imagine polyesther or polyvinyl interior glass, or would I need to use a similar glue.
    Thanks
    Chandler
     
  8. Ike
    Joined: Apr 2006
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    Location: Washington

    Ike Senior Member

    Actually that has been done on a lot of boats with blistering problems. As was said, water will migrate (very s....l....o....w....l....y) through gelcoat and through fiberglass. This can result in blistering. One of the solutions is to completely strip off the gelcoat and even some of the top layer of GRP, reglass with epoxy resin and then coat with an epoxy barrier coat and epoxy paint. But as I said that is only one of the solutions. Before doing this though, you have to completely dry the laminate, which means your boat will be sitting on the hard under a tent for a long time.
     
  9. SamSam
    Joined: Feb 2005
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    Location: Coastal Georgia

    SamSam Senior Member

    You went about this in a strange way. It's kind of like asking about bark when you need some wood. If you take off the gelcoat, the glass and then the core, you really don't have much left. A little more and the next thing is the back of the upholstery and the inside of the cabinets.

    It doesn't sound feasible to me.
     
  10. chandler
    Joined: Mar 2004
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    Location: U.s. Maine

    chandler Senior Member

    The point is that the upholstery and interior wood work are in excellent condition, the hull has some problems that can be fixed from the exterior.
    The core is the problem, ie balsa core.
    If the core is done, since it will never dry, why not take it down to the inner glass, I'm hoping preserving the shape of the hull with all interior bulkheads in place.
    The yard quoted 30,000 plus to repair the hull.
    I think I can cold mold a 33' hull for alot less than that provided I'm not starting new with molds etc.
    I know I went about this in a strange way but not being familiar with grp hulls thats how I started.
    Now my question is will epoxy adhere to the inner glass hull or does it have to be poly?
    I'm a wood worker for 30 years, alot of experience with epoxy, none with polyvinyl or whatever they call it now days. Does it sound like it will work?
    I don't want to deal with gell coats, I've built several small glass and wood boats with poly paints, I'd like to keep with what I know and avoid gelcoats.
     
  11. Stumble
    Joined: Oct 2008
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    Stumble Senior Member

    Chandlier,

    I have a few questions for you...

    You said that the core is saturated, but is it rotten? Wet core can be dried out by tenting the boat and placing a large quantity of dehumidifiers and heaters around the hull in an attempt to lower the relative humidity as much as possible. Leave the boat sitting like this for 6 months or so and the core should be dry.

    Balsa ROT on the other hand is irreversable damage caused by a combination of water and microbes that break down the wood. If what you have is rot the whole effected area must be cut out of the hull, the core replaced, and the skin reapplied. Depending on the size of the rotted are this could be anything from a few minutes with a hole saw to add a through hull fitting you don't need to redoing an entire hull.

    The problem is that as the size of the rotted area gets larger the cost goes up, until you pass the point where it is too expensive to repair relative to the value of the boat. Once this point is reached the only reason to repair the boat is for love of a historically significant design/hull.
     
  12. gonzo
    Joined: Aug 2002
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    gonzo Senior Member

    Those boats have balsa core on the whole hull and deck. I am redoing the teak deck, electrics and a lot of other stuff on a customer's Freedom of the same year. The craftmanship and finish is poor. Have you checked the deck? The ballast is in sections and tends to move and come loose. The bolts are stainless and prone to crevice corrosion. If you like wooden boats, there are wooden boats for sale. Otherwise, you will spend a lot of money on a boat that will still smell like plastic inside.
     
  13. chandler
    Joined: Mar 2004
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    chandler Senior Member

    Stumble and Gonzo,
    I don't know if the core has any rot or not, from everything I've read about cored hulls I think your wrong about trying to dry a wet hull unless you drill a million holes in it and use a proactive approach such as hair dryers. My concern is the boat has been in fairly warm waters for several years avoiding the freeze thaw cycles she will experience in Maine causing delamination.
    One of the reasons I want to save this boat is because of the excellent craftsmanship of the interior joiner work, besides the fact she meets all my requirments. She doesn't look or smell like plastic!
    I've had a full survey done and the only problem is with some portions of the hull, deck is fine.
    If I could afford a wooden boat I would build it myself.
    My original plan was to design a boat that I have spent 6 years doing only to find that I could buy a used plastic boat that met my needs for less than I could buy the engine and spars for never mind the hull, interior, and all the other costs associated.
     
  14. jim lee
    Joined: Feb 2007
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    jim lee Senior Member

    It seems to me that attempting to fix wet core by sanding through the gelcoat is kinda' like fixing your car engine by sanding through the hood.

    Did the survey people map out the sections where the core is wet?

    -jim lee
     
    1 person likes this.

  15. tunnels

    tunnels Previous Member

    Are you one of those people that like messing with boats or messing around in boats on the water ?
    If it is the boat you want then rebuild the outside plus the core . Glass boats are not impossible to repair even with half a side missing its still possible to do the repair and make it better than it was before . If you want to keep the cost in the back ground and love the boat then i would repair it,you will then have the boat you want .Simply put you would be male moulding the hull working from the inside layer back to the outside again and you could finish up by painting it rather than Gel coat . :)
     
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