Gel Coat vs Bed Liner

Discussion in 'Fiberglass and Composite Boat Building' started by hardcoreducknut, Dec 14, 2011.

  1. hardcoreducknut
    Joined: Aug 2011
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    hardcoreducknut Junior Member

    I'm in the process of designing a Polystyrene marsh sneakboat for duckhunting. I of course plan on using epoxy resin and will have to coat it.

    I'm debating on using bed liner vs gel coat due to it's toughness. I'm guessing bed liner will weigh more, but offer more protection. Any input on this would be much appreciated.

    Thanks!
     
  2. ondarvr
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    ondarvr Senior Member

    Since gel coat doesn't bond all that well to epoxy you can scratch it off the list of options.
     
  3. OFFSHORE GINGER
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    OFFSHORE GINGER Junior Member

    unless ....he uses a primer first .......for that type of application , and one of those primers are made by Durtech. http://www.expresscomposites.com/duratec.html
     
  4. ondarvr
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    ondarvr Senior Member

    More weight, more complicated, more $$$, so why go that direction when there are other less costly, easier, lighter and better options...like maybe paint.
     
  5. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    Truck bed liner coatings are specially formulated, modified polyurethanes. They aren't high gloss and chalk up pretty quickly in most colors. They tend to go down heavy (30 mils plus) and you need to spray the high cyanoacetate formulations (special guns) with care, if you want a smooth finish. You can paint over them, but the dramatic difference in film elongation, will likely cause issues on a boat.

    I'll second the paint option, as it's the economical method with easily obtained, spectacular results. This isn't true with both gel coat and truck bed liner. With some skill, well controlled conditions and an experienced sprayer, you can get a very good gel coat job, but this would be a rare thing from a shade tree type of situation, that the typical home builder would produce.
     
  6. the1much
    Joined: Jul 2007
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    the1much hippie dreams

    id buy a truck for my bedliner hehehe hiya par niceseein you again ; }
     
  7. latman
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    latman Junior Member

    when you say coat I assume you will be using epoxy resin to wet out a reinforcing fibre cloth (otherwise it will be brittle/useless IMO and then the PU Bed liner coating is the way to go after that is all nicely sanded up !!
     
  8. OFFSHORE GINGER
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    OFFSHORE GINGER Junior Member

    ondavr , just curious what is so complicated about it........ considering most areas or any surface that needs to be painted usally will require a Primer prior to painting which most likely will be a primer that is recomended by the manufacturer of the paint but then again there are a lot of primers out there...... that are compatible with just about everything . Hey guys , my neighbor, is in his late 70's has been painting is duck boat with Sears Weather beater for the last 30 years which really does not look that bad ,and if cost is that big of a concern ,and something as simple as prepping a project for paint (Primer).............................why not .
     
  9. ondarvr
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    ondarvr Senior Member

    Special order it, have it shipped (hazardous material $$), catalyzed with an application window, etc.
     
  10. OFFSHORE GINGER
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    OFFSHORE GINGER Junior Member

    hey guy not to be rude................but you sure are Mr negative considering just about everything that is used in this industry has a window from resin to paint and to tell you the truth just how many people have the luxury of going down to the corner store and buying resin , Gel ,Fabric ,Core , Cabosil , Bagging supplies , Primer , ect ,ect, without having to order it :?: Done ................ :)
     
  11. idkfa
    Joined: Sep 2005
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    idkfa Senior Member

    Seems a large part of the problem is spraying, most of the products use 30,000US plural component spray equipment.

    Also getting a smooth surface may be impossible?

    http://www.youtube.com/watch?v=njsZW81_Aec&feature=related

    http://www.pickupspecialties.com/Bedliners/do-It_yourself_spay_truck_bed_liner.html

    www.rhinoliningsindustrial.com

    other info pick-up online:

    Polyurea elastomer systems are amorphous in nature, not crystalline
    like polyurethane systems. This amorphous nature is similar to that of
    epoxy type systems except that polyurea system do not have a true
    glass transition temperature.

    What's the difference between aromatic and aliphatic polyurea systems?

    The typical aromatic
    polyurea systems must be processed through high pressure, heated
    plural component pumps and sprayed through an impingement type
    spray-gun.

    This is true also for the aliphatic version of this type of
    system, the primary difference being the color stability of the
    aliphatic systems.

    Actually there are two different types of aliphatic polyurea systems
    currently on the market. One is the typical high pressure/temperature
    sprayed systems and the other is what is known as a "polyaspartic
    polyurea" type system. This polyaspartic system is different in that
    it uses an ester based resin component and has a longer pot life. It
    can be hand applied using close nap rollers; brushes; rakes or even
    airless sprayers. The aspartic systems are not the high build coating
    typical of the "hot spray" polyurea systems.

    How should polyurea be prepared for overcoating after initial cure of
    the polyurea?

    Prior to overcoating polyurea make sure it is clean. For the first
    several hours after polyurea has gelled it may be suitable for
    overcoating without further preparation. If polyurea base coat
    material has been in place for longer than six hours there could be
    problems with inter-coat adhesion. Since fewer products are carried in
    aromatic solvent, which tacktify polyurea you must undertake this
    process. To assure inter-coat bond apply a liberal amount of denatured
    alcohol (or more aggressive solvent such as acetone or MEK) to
    polyurea and allowed to evaporate completely. This will re-tack the
    polyurea base coat and allow proper adhesion of the follow-on
    overcoat. This same procedure should be used when bonding polyurea to
    polyurea after initial cure has taken place.
     

    Attached Files:

  12. ondarvr
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    ondarvr Senior Member


    Not negative, just realistic. He can go down to the local hardware and store buy primer and paint that will work fine on a project like this for a fraction of the cost of buying gel coat and a suitable primer for good adhesion to epoxy, and that's before the cost of shipping.
     
  13. hardcoreducknut
    Joined: Aug 2011
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    hardcoreducknut Junior Member

    I appreciate all of the responses thus far. I guess there might be some questions why I am asking about bed liner.

    I guess I should have mentioned a little more about what I'm doing, this post may illustrate. The boat I am going to build will be much more...sexy. I'll have nice lines, conduit for wiring lights, switch panels, sub-floor, etc...basically a dream duck hunting layout boat. I plan to build it this coming off-season to have ready for 2012-2013.

    I really don't care about cost. If I wanted cheap I'd just buy another boat like mine off Craigslist for $400 and call it a day.

    The reason I am asking about bed liner is we have to break ice often when duck hunting here in NW Missouri. Something I've done plenty of times with my current layout boat that uses polyester resin. I don't have any cracks or leaks (that I'm aware of) from this...yet. However, I know that epoxy is stronger and it won't melt polystyrene.

    From the responses thus far, paint is cheaper, easier and only offers aesthetics and UV protection. Bed liner is more expensive, requires more prep and offers more protection than just UV but often fades in color to a gray. The boat will be completely covered in grass and sloshed in mud. I doubt anyone would see that.

    Am I correct in my thinking that a commercial application (line-x/rhino liner) would be preferred over Herculiner?

    Ondavr: You're right, I'm using epoxy to wet out fiberglass.
     

  14. ondarvr
    Joined: Dec 2005
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    ondarvr Senior Member

    That helps a great deal.

    You can use paint on the topside and a truck liner type product on the bottom if you think it will be subjected to a great deal of abrasion. Use a very flexible brand though, some are rather stiff and may crack or chip. They can also be heavy, so don't over do it.
     
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