resin bonding issue Apoxy vs Vinyl vs Ploy

Discussion in 'Fiberglass and Composite Boat Building' started by Cebu, Oct 21, 2010.

  1. Cebu
    Joined: Oct 2010
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    Cebu Junior Member

    I have been putting off building this boat for 30 years and finally at 52 I seem to have enough $ to build a poly boat. The problem is I keep reading posts that state that I cannot build in poly or vinyl due to the water seepage causing delaminations. I cannot afford to build with epoxy. If it is to be epoxy then it will not get built, and if it is poly it will fall apart.
    I plan on using a mold. The posts claim I can apply epoxy to poly but not poly to epoxy. Well if I am using a mold and the outer layer needs to be epoxy and the inner layers poly, am I screwed. Do I lay both layers while both are still wet, and then all future layers are ok to lay poly.
    I guess I should further clarify my construction technique first. Thirty years ago I developed a fiberglass/cardboard sandwitch process after attending a flyin in Oshkosh, Wisconson. A aircraft designer named Molt Taylor had built a plane out of cardboard covered with fiberglass. His material was strong and lightweight. He used solid cardboard like you see on the back of a pad of paper. I knew I did not have enough money to build a plane but I thought I could build a boat. I made a test sample 1 foot square. It had two layers of fiberglass and resin laid one at a time then I laid a wetted sheet of corrigated cardboard, then wetted the dry side and laid another layer of glass. I ended with glass,glass,board,glass,board,glass,board,glass,glass. It took less that an hour to finish. I found this in a box about 6 months ago and got me back into the fever again. This was so light and strong I am going to use it to build my Mississippi river Jon boat.
    So can anyone tell me if I can put epoxy on the outside of my boat if I layup the two layers at the same time and not have seperation and still retain my epoxy weatherproofness.

    Sorry to make this question so long.
     
  2. apex1

    apex1 Guest

    You can build your boat in polyester, no problem. Applying a gelcoat on the mould as your first layer will keep the water out of your hull layup. That is the standard procedure in the industry.Todays materials are better than those some years ago. VE would even make a better prevention on the outside, but is not as easy to process as poly. (and not as cheap)

    And epoxy would stick to poly! Just not vice versa.

    If in doubt, you could apply a epoxy coat on the underwater section of your hull, before you put antifouling on it (if any).

    Your cardbox idea does not sound very promising. For a boat you cannot use that layup. The cardboard is structurally too weak. (and I doubt the success on the airplane too)

    Regards
    Richard
     
  3. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    Richard, I suspect the cardboard, in this case what the printing and paper industry call "chip board" (the stiff, grayish brown backer board to note pads) is used as a form only. Corrugated cardboard would be used the same way, with some compound curve advantages and some disadvantages too. I'd stick with chip board as it has fewer disadvantages then corrugated.

    Used in this application the 'glass work forms the structure and the board along for the ride, initially offering something to preform the layup on.

    I hope you like sanding Cebu. The method you've chosen requires lots of fairing (smoothing) and sanding your brains out will become a common theme of you days building this puppy. Lastly, have a professional spec out your laminate schedule, so you don't run into local or global strength issues.
     
  4. SamSam
    Joined: Feb 2005
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    SamSam Senior Member

    Corrugated cardboard would make a boat full of channels that would fill with water from the least little hole and allow that water to travel long distances almost instantly within the structure of your boat. It might be light and strong, but put your test panel underwater for awhile and see if it's a good way to make a boat.
     
  5. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    I didn't try to get into details Sam, but this is one of the disadvantages of corrugated cardboard. In the same vain, if corrugated cardboard was used, but first covered with Visqueen, plastic packaging tape or similar, the cardboard form could be pulled out, after the exterior skin cured. I can think of a few "one off" methods that could use cardboard as a form.
     
  6. leaky
    Joined: Sep 2008
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    leaky Senior Member

    For starters I'm not sure why weight is such an issue in this application. Why not go with an all glass hull? Or a glass hull which is slightly thinner but better supported with a light encapselated wood structure inside?

    That wouldn't require anything other than classic poly construction. You could even do your wood encapselation in epoxy and everything else in poly, which would more/less give you the best of both worlds.

    Otherwise.. I think anything you do sub-waterline where a material is used that can absorb water will..

    Yes there have been long-lasting large production balsa core saltwater boats (ie blackwatch) made to be strong and light, moving faster with less power and fuel, which mostly hold up if the correct care is taken and nothing goes wrong.. but that's also saltwater that helps preserve wooden material.

    It's that classic problem. Taken a wooden boat, which is a good boat that happens to have a few (maintanable) problems, wrap it with fiberglass, and eventually that's the nail in it's coffin.

    If it must be *that* light and *that* strong (are you racing this thing? BTW aluminum would be a better material for strength and weight) I think you'd be better off building your mold or plug, laying a skin, then lay tabs off the skin a few inches long, then lay foam in between the tabs, then glass over it grabbing the tabs and use the tabs as ribs on the inside of the hull (foam or wood on the inside of them if you'd like). It'd be like production boat's "I-Beam" stringers on the hull itself... Just use whatever pattern makes sense.

    Again I think it's silly for the weight reduction versus "cost" in labor, but you could do it all poly and with a closed cell foam you'd have a material that won't suck up water for a long time, and a very strong construction that would allow puncture of a single layer without any effect. I would definitely epoxy coat the bottom with such construction.

    Just my humble opinion.
     
  7. tunnels

    tunnels Previous Member

    If you are worried about osmosis and the like !!
    Gel coat t the required thickness and with the appropriate catalyst at the right ratio to get the correct hardness etc
    Then backed up with a layer of Continuos strand tissue with a layer of P matt chopped strand but use Vinyle ester resin for this layer and make it resin rich and well rolled out so there are no air bubbles any where ,then you can build the rest of the boat in polyester !!! For a step better use Vinylester for the rest of the boat . will be much cheaper than epoxy !! If you buy at drum rate from the supplyer you could get a better price than in smaller containers . Shelf life is 6 months or longer but need to keep it well stired regularly . In warmer weather the resin separates out and heavy settles to the bottom .If stired well you can get more than 6 months to use it all . :)

    Why do i say to use P matt ! because it is a powder binder and is far less prone to holding moisture if you are in a place of high humidity .
    If it possible you need to be able to get a handle on you working enviroment during the whole of the major glassing process .
    Find the resin manufactures specs and exceed them a little to be on the safeside . Store all you materials like glass etc in a dry warm place
     
  8. SamSam
    Joined: Feb 2005
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    SamSam Senior Member

    Well, the guy said he was going to "use a mold" but didn't state what sort, female or male or what it's made of. Then he describes a test panel with 3 layers of corrugated cardboard embedded in the layup and said that's what he's going to use to make the boat itself.

    I've used it to bulk up and stiffen a mold once the inner laminations were thick enough and it worked fine, but molds aren't subject to the stresses of a boat or sitting in water as a living.

    It seems an over thought project unless his idea of a Mississippi River Jon boat is different than mine. I think he's more interested in the process than the project, which is alright, but if money is limited, cheap materials can be very costly sometimes. And a 1' square test panel may not act the same when used in a full sized boat, especially if it hasn't been tested to destruction under controls.

    Regarding his basic question, what would happen with a wet poly laminate laid directly on a wet epoxy laminate?
     
  9. apex1

    apex1 Guest

    Regarding his basic question, what would happen with a wet poly laminate laid directly on a wet epoxy laminate?[/QUOTE]

    It comes apart..........
     
  10. Cebu
    Joined: Oct 2010
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    Cebu Junior Member

    I see I left too many questions just to get the answer about poly and epoxy. First I am using a mold so

    I will not have to sand much. I don’t care that much about how pretty the boat is, I just want a smooth

    Outer surface. I plan on using the cheap paneling they use in shower and bathroom stalls. It is a smooth clean surface. I have no compound curves; actually there are no curves at all. It is a Jon boat with the current dimensions of 7.0 feet wide with 3 inches outward flare on each side for a total width of 7.5 feet. Length is 22 feet. The front sides tapers up to 8 inches. As for the size, I've been on the Mississippi river and have come close to being swamped by the big freighters wake. I also will be out there most days by my self so light weight is a must considering my age and I will be trailering it over 100 miles each way. As for those who still don’t understand cardboard. It looks like this.

    ___________________
    /\/\/\/\/\/\/\/\/\/\/\/\/
    ---------------------

    It is not chipboard it is paper with a corrugated or wavy center made of paper. As for its strength,

    You nay Sayers have no idea of it's power, and APex1 you have no idea of what your talking about. In the seventies there was a commercial with a bridge built from corrugated cardboard and Bob Hope stood under it and someone drove his Rolls Royce over it. Houses have been build with it and ever tried to punch your way out of a card board box two layers thick.

    My current design is similar to the test panel I have described in my original question. It will be from

    the outside inward for the "FLOOR" glass,glass,glass,board,glass,board,glass,board,glass,glass. This seems like a lot of structure but there are a lot of underwater obstructions in the river. I hope my design with cardboard will act as a crumple zone. I hope when I strike a underwater log and it will act like a cars crumple zone and absorb the impact preventing a through and through and start taking on water. All the air pockets in the cardboard will be isolated from each other and should remain sound and water tight.

    As for the "SIDES" it will be a lot less. Glass,glass,board,glass,board,glass,glass. Sides will be 18 to 24 inches high, have not decided yet. It will also have a fiberglass cabin mounted 4 feet back from the bow. Safety is utmost and with the hundreds of air pockets it will not sink. I am also considering punching small 1/4" wholes in the cardboard to create support columns directly connecting the glass layers with solid resin.

    SamSam-
    Thank you for your constructive comments. I will make up a new panel some day maybe soon and test it submerged and maybe even a punctured panel soaked in water. As for being more involved in the process and design than the project, that may be true as I am an engineer. And the mold will be removed as soon as possible and the boat placed on the floor to reduce warpage. The panels should just peal off if I put a couple of layers of releasing agent on first.

    Please any comments are welcome; it has restarted my design wheels going again.

    My start date for the project is in late March.
     
  11. Cebu
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    Cebu Junior Member

    I just had a idea for increasing the impact resistance of my hull design. I saw the SRV Dominator vehicle on "Storm Chasers" on the weather channel and it uses "Rhino Linings -HARDLINE" to make their tornado shell impact resistant. That might be useful to deflect log strikes.

    Does any one have any experience with this material, their web site states it is for boat use too.

    Any comments welcome

    Cebu
     
  12. apex1

    apex1 Guest

    That was a floating bridge?

    Maybe it helps when YOU come out of your cardboard box?

    But, do what you want, what have I to do with it. You are not here for advice! You are searching a confirmation of your (non mature) preconception.

    Over and out.....
     
  13. Cebu
    Joined: Oct 2010
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    Cebu Junior Member

    This is for PAR

    I reread your reply to my question and want to thank you for your advise but, there was one line I did not understand what you were talking about. Could you elaborate in more detail on

    "Lastly, have a professional spec out your laminate schedule, so you don't run into local or global strength issues."


    ThanX

    Cebu
     
  14. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    I you have to ask, you surely need the engineering help. Working out the scantlings, particularly on laminates and especially on non-conforming laminates (odd balls), requires a fair bit of engineering to insure you aren't surprised by failure, in what appears a reasonably innocuous area or structural element, let alone a catastrophic event.

    The simple reasons we need to do this are to save money, time, labor and materials.
     

  15. SamSam
    Joined: Feb 2005
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    SamSam Senior Member

    Actually, you leave it in the mold as long as you can to help prevent warpage.

    Corrugated cardboard has an excellent strength to weight ratio until it gets wet, and then it becomes wet cardboard.

    If you don't get all the inside and outside surfaces and all the corrugations covered with a waterproof resin (polyester is not waterproof) your boat will become like wet cardboard pretty soon.

    On the other hand, if you do somehow managed to get all the surfaces covered with resin, your boat will weigh about 38 tons (exaggeration) because the same way cardboard absorbs water, it will absorb very expensive waterproof (epoxy) resin.

    If that doesn't make you wonder a little bit about using cardboard in a boat laminate, in all the years I repaired fiberglass boats, as shoddy and crappy and cheap as some mfgrs made them, I never did run into any cardboard used in any laminate or any way whatsoever in their construction. If it had had any chance of working, you can be sure they would have stuffed it in there wherever it couldn't be seen.

    You have a test panel, cut it in half (across the corrugations) with a hacksaw. That should let you see how much the cardboard got coated on the inside corrugations. Then submerge it in water, and every few minutes pull it out and twist it a little bit back and forth. See what happens and then report back.
     
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