Confused on the order to do layup

Discussion in 'Fiberglass and Composite Boat Building' started by Buckeye492, Aug 12, 2019.

  1. KeithO
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    KeithO Senior Member

    That is my point exactly. If I go out and try to buy a gallon of VE resin, it will cost me the same price as if I bought West system epoxy. So if as a private person you are not saving any money when buying VE resin and has to deal with adding wax so that the surface of the final layer does not stay tacky forever, which means any further bonds will be forever compromised, why do it ? I understand that boat builders get a special deal on their huge annual resin purchases and want to use the cheapest stuff that they think will do the job. But I get no such break....

    Youtube is full of examples where you can peel apart secondary bonds by hand when people are doing yacht renovations, and the former bad workmanship is almost without exception resolved with grinding the surfaces with 36 grit paper to remove all traces of the previous bond line and then laminating up new glass using epoxy.

     
  2. ondarvr
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    ondarvr Senior Member

    I don’t watch YouTube for my information, I’ve done this for a living for 50 years.

    I now work with composite manufacturers to help them build better quality parts quicker. From Mega yacht builders to aerospace.

    We do destructive bond texting, I know the results when using different resins.
     
  3. Deering
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    Deering Senior Member

    All claims about bonds and costs and professional credentials aside, polyester resin is foul to work with. It stinks. For that reason alone epoxy would be my choice.
     
  4. rwatson
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    rwatson Senior Member

    .. and VynilEster is 100 times worse. It was absolutely foul.

    "Epoxy is known for its higher bonding capabilities overall. An epoxy’s relative strength can hold up to 2,000 lbs. per square inch, while a polyester resin can hold less than 500 lbs. per square inch."

    "Epoxy is very moisture resistant, and certain formulations can even be applied underwater. Polyester resin has minor resistance to moisture, is considered water-permeable, and can fracture easily."

    What is the Difference Between Epoxy and Polyester Resin? – Protective Coating Company https://www.pcepoxy.com/what-is-the-difference-between-epoxy-and-polyester-resin/
     
  5. fallguy
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    fallguy Senior Member

    Ondarvr makes a good point.

    I have used 227 gallons of epoxy in my build. Scary; that is a ton. Falldown for vac work is probably close to 25%, or 750 pounds per hull.

    For a small repair, there is little reason to use alternatives.

    But in a big build; epoxy at $100 a gallon adds up in a hurry. The only reason I used it was a budget miss and I can't have the stink of pe in my home.
     
  6. redreuben
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    redreuben redreuben

    What ondarvr said,
    the rest is mostly regurgitated myth from reading forums to much.
     
  7. rwatson
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    rwatson Senior Member

    Would that include the actual performance statistics quoted too?
     
  8. redreuben
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    redreuben redreuben

    Watson statistics are irrelevant, epoxy on a polyester boat is lipstick on a pig.
    Further it then means you're committed to it so rather than finish with some flocoat or a waxed gelcoat spray you now have to use 2 pack high builds and urethanes,
    STUPID.
     
  9. ondarvr
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    ondarvr Senior Member

    This topic frequently turns into a heated discussion on which resin type is “better”, when the actual question is which resin will do the specific job in question and last in the real world.

    The answer to that, and it’s been proven for some 60 years, is that both will.

    To make the best use of epoxy it should be planned for right from the design stage, and actually engineered to use the correct fabric types in the correct order. Then the entire structure needs to be post cured or you won’t come close to those impressive advertised physical properties on the data sheet that people love to repeat.

    If his boat had originally been built with epoxy, or he was modifying it for high performance and adding mega HP, then epoxy might be a good choice. But for a small boat, with modest HP at best, there’s not even a remote requirement for epoxy. Not that it couldn’t be used, just that there’s no real benefit.
     
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  10. ondarvr
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    ondarvr Senior Member

    Now if you just like to use epoxy, or if you don’t like the odor of other resins, then by all means, use epoxy. But don’t try to make it sound like it’s the only product that should ever be used to do a repair.

    My Honda Civic has 5 lug nuts on each wheel, this design doesn’t fail. So since a new 1 ton diesel has 8 lug nuts, should I use 8 on my Honda?

    This is the same kind of logic used when doing a repair like the one in this thread.

    Let’s make something that didn’t fail during the 40 prior years of use much stronger than it was before. This may make you “feel” better, but is of no benefit in how well it will perform in the next 40 years.
     
  11. Buckeye492
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    Buckeye492 Junior Member

    I am hanging a 350-400 lb 140HP Evinrude on this transom if that helps at all. I don't think I need to make this thing into a battleship, but I just don't want the transom failing as I am cruising across the Chesapeake Bay either. Correct me if I am wrong, but Poly or VE resins (smell not withstanding) should be more than sufficient for my application if I am reading the comments correctly. I figure with a 12:1 grind angle & 5-6 layers of 1708 should match the original thickness pretty closely. Then just fair it & I should be good to go....I think
     
  12. ondarvr
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    ondarvr Senior Member

    Yes

    This is the normal method, pretty standard layup. I will say that many layers of 1708 is more than typical though.

    The original transom was CSM/chop and roving, what you’re adding is stronger.
     
  13. ondarvr
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    ondarvr Senior Member

    I first posted this many years ago.

    ————————————————————
    “I deal with many different markets in the composites industry, not just the marine end of it and for the most part I agree with XstreamVking.


    Since I don't see bond failure as an issue in anything I've built or repaired with polyester or VE over the last 40+ years, and it isn't really an issue for my customers, which have built many thousands of boats themselves, it seems the bond issue is more a case of poor workmanship or bad design. The prep needed for either type of resin is the same, epoxy may let you do a poor job with a little better chance of success though.


    When I see bond failures it’s typically when a rookie decides to do a F/G repair on his boat (you can insert any item in place of a boat) and heads down to the hardware store. They buy whatever resin it is that has been sitting on the shelf for a couple of years and some cloth (no mat), no sand paper, acetone, or any other needed items. They pull the boat out from under a tree in the side yard, use a damp cloth to move some of the leaves away and then make a feeble attempt to wipe off the green and brown slime that has accumulated on the surface for the last 10 years.


    At this point they remember they should sand the surface, so they go back in the garage and find an old piece of fairly fine grit sand paper that's been used many times before on other projects. Now they make a couple of half hearted passes over the surface with the sand paper, which instantly clogs up with the damp green gunk still on the surface. It gets one more wipe with an old rag that was last used to check the oil on his truck and he now feels he’s ready to catalyze some resin.


    Now, how much catalyst to add…..was that 2%, 20%, 50%...and how do you know what 2% is…or did they say 2 drops per quart…oh well, it’s not that important, I’ll just poor a little in…oops…too much (I think). Now where is that old paint brush I used to do the trim on the windows a couple of years ago…..there it is…wow, maybe I should have cleaned it better…sort of stiff. OK, now I just pour some resin on the surface and lay this 1’x1’ piece of cloth on it, I only “prepped” a 6”x6” square, but it should be fine…maybe even stronger. Let’s see, what do I do with all this extra resin…it sure took a lot less to wet out that piece of cloth than I thought. I think I’ll just pour the rest of it around on some of the other cracks to strengthen other areas too…don’t want to waste it. Looks like rain…good thing I’m done…now I’ll go in and have a beer.


    A week later he heads to the lake puts the boat in the water and it doesn’t leak, it was a successful repair. Two weeks later he runs over a big wake while pulling a tuber and the repair starts to leak, he reaches down and grabs a corner of the cloth that is sticking up, the part he couldn’t get to lay down, must have been because it was folded over. He pulls and the cloth comes right off with little effort and he's shocked. That night he goes on line and asks on a boat forum why it failed, he tells them he did everything according the directions but it still failed. He is told that polyester resin is very weak, won’t stick to anything and that he needs to use epoxy, so he orders some online the next day.

    While waiting for the epoxy to arrive he starts to clean off the “failed” polyester resin and finds it is sticking in some areas and won’t chip off. About this time the neighbor sees what he is doing and offers him the use of a small grinder, this speeds things up dramatically and removes all of the old resin and green slime that was still on the surface. A couple of days later the epoxy is delivered and so is some biax, he also ordered the roller and squeegee the guys online said he would need, plus he picked up some new brushes.


    This time he remembers its a 1 to 1 mix (and with a little work he can figure how much of each that is), stirs it well and from his experience before, plus the advice from the forum, he uses the correct amount of resin to wet out the several layers of glass to build the surface back up and works all the bubbles out.


    This time the repair holds up, now he goes back online to the forum, he’s one of the experts on the forum now because he’s done a repair before, and tells everyone how bad polyester is and that they should never use it, and epoxy is the only thing that works.

    Sound familiar.



    Back to the other stuff.


    If properly designed an epoxy hull will be no stronger than a polyester or VE hull designed for the same use, only lighter, this is where the DIYer comes up short. They tend to use about the same laminate schedule as they would with polyester or VE, so they have the same weight with a much higher cost and an over-built part, or repair, this results in no advantage or benefits from using epoxy. I hear people frequently say that you will save weight by doing an epoxy repair, well it would need to be a very large repair to make a meaningful difference in the weight savings. You may save the weight of a six pack on a large repair...and well….that may be very important to some people…more beer.


    As for strength, most epoxies list their physical properties after being post cured, if you don't post cure it don't expect to get close to them. Also any medium to slow cure epoxy really needs to be post cured, they fall well short of the listed properties without this step.


    The other issue with strength is when using low viscosity epoxy infusion resins is they tend to be much weaker than higher viscosity resins. This has to do with how they reduce the viscosity. What can happen is the physical properties can drop to a level equal to, or below those of a VE resin.


    Even the many thousands of low quality ski boats built to a very low price point with the cheapest polyester resin available, rarely have an actual resin/glass failure, the wood rots and they tend to hold up OK until the wood is nothing more than pulp. And even then the owner has no clue there is an issue until his foot falls through the deck.


    As for high end custom or semi custom boats, why not use epoxy, it’s a great product and will allow you to build a much lighter craft. These tend to be purchased in relatively small numbers by people that can afford this type of toy, not the every day guy.


    As for the type of boats repaired or modified on this site, epoxy may be a good choice for them, that is if your plan is to put the largest outboard on it you can and then push it to the limit. Although a VE is easily up to the job. For the many more that just want their ski or fishing boat back on the water, I can’t see a good reason for using epoxy.”
    ————————————————————

    This was all from a similar thread discussing epoxy and polyester.
     
    Last edited: Aug 25, 2019
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  14. redreuben
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    redreuben redreuben

    Ondarvr, that was funny as f*#k.
    ROFPMSL.
    Wipes coffee off keyboard.
     

  15. Buckeye492
    Joined: Aug 2019
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    Buckeye492 Junior Member

    Ondarvr, I got quite the chuckle out of that because I've seen others do basically what you have described. I was formally trained an number of years ago on fiberglass & composite repairs, but to be honest, I've forgotten most of what I learned because I simply never use the skill. Thus my reason to be on this site. I have learned a great deal just in these couple of pages & feel confident that I can complete this transom and not have any worries about failure now. To all that have commented, thanks for all the insight!!
     
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