Stitch & glue outrigger to glass inside or not?

Discussion in 'Multihulls' started by erikhaha, Jun 12, 2010.

  1. ancient kayaker
    Joined: Aug 2006
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    Location: Alliston, Ontario, Canada

    ancient kayaker aka Terry Haines

    I'm not sure I would trust a "penetrating" sealing coating of any description that contained solvents. I would be concerned with the solvents penetrating faster than the sealant and then being unable to evaporate completely through the sealant layer once set. I would be particularly suspicious of a thickened epoxy that was then thinned with a solvent: I can just imagine all those ingredients all wanting to do their own thing and leaving several layers of nobody knows what behind.

    I prefer paint to epoxy. Its sealing properties are not as good but they are built up gradually and each layer can rid its own solvent which is prevented from preferential penetration of the substrate by the previous layers. Whatever water gets through can at least get out again.

    I have experimented with heating the wood before applying epoxy. The epoxy does penetrate deeper improving the adhesion when used on end grain by partially filling the grain to a greater depth and preventing voids. I have verified this for joints by testing, with butt joint strength of the order of 75-90% of wood strength, compared to about 50% for epoxy applied cold. I haven't tried it for sealing since, as noted above, I prefer paint, and it would be difficult to do uniformly over a large area.

    Nonetheless, my advice to leave the inside of the amas unfinished remains good IMHO.
     
  2. DrCraze
    Joined: Apr 2010
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    DrCraze Junior Member

    So now its "we" and before it was "I"? You just cant make up your mind can you. There is a huge difference between first hand experience and whatever it is you do when you're not trolling up a storm in here.:)
     
  3. AndrewK
    Joined: Mar 2007
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    AndrewK Senior Member

    Regarding the side topic of waterproofing, Apex has provided the right advice you want undilutred epoxy to surface coat the timber. I hate the term frequently used "epoxy saturated timber construction" there is no saturation taking place at all, it is only surface coating. Reducing the viscosity be it with solvents or reactive diluents only marginally increases the penetration into side grain. As pointed out solvents will reduce the waterproofing while reactive diluents will not but they will not improve it either. Even in the extreme case, end grain balsa resin infused at 100% vacuum will only increase in weight by few %.
    History has shown that marine epoxy systems are fit for purpose even though they are not 100% water proof. You should have a minimum of 3 neat coats to provide a thick enough surface coat.

    If one really wants something better then don't waste your money on reactive diluent's but get a curing agent that provides a more water proof plastic.
     
  4. redreuben
    Joined: Jan 2009
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    Location: South Lake Western Australia

    redreuben redreuben

    Well at least we're back on topic! Can you expand a bit on the curing agent aspect please ?
    RR
     
  5. apex1

    apex1 Guest

    Thats easy to answer.

    For every resin on the market one can buy dozens of hardeners / curing agents to formulate the cured product to meet different requirements.
    But NONE of them provides the often claimed deep intrusion as I mentioned a few pages back, and Andrew now again!
    Thats all.

    DrCrazy you should apply for a senior teacher job, your attitude is common there.
    I feel no obligation to comment further on the output of my yards.

    Regards
    Richard
     
  6. Chris Ostlind

    Chris Ostlind Previous Member


    Andrew,

    Could you be so kind as to define the term... saturation, then?



    I get that you've drawn-up a mental picture of a piece of wood that has been dunked in an epoxy bath, it is permeated through and through with the chemistry and then left to cure. I would suggest that the term being loosely used in the reference that drives you crazy, is actually more about surface saturation. There's somewhat of a disconnect on the part of those making the soaked comment in not seeing the process well.

    Whether you guys like it or not, there is very definitely penetration taking place in all cases. It's measurable and visibly keyed through simple application. Typical marine plywood materials are what I would call, absorbent strata. The very fact that you are concerned about water migration into the various strata indicates as much.

    Why is it so difficult to complete the understanding when applying epoxy and its associated chemistries, however they may be formulated? Nobody has shown me yet, that the lengthened epoxy molecule has any trouble, whatsoever, in being absorbed by the incredibly porous surface of marine plywood. If you have such data and microscopic photos in support of the epoxy not penetrating the surface, I would love to see your presentation.
     
  7. apex1

    apex1 Guest

    Why should one prove that steel is harder than wood? The entire industry knows that.

    Try to get a block of endgrain Balsa penetrated thoroughly by epoxy resin! Even a very thin formulation does not do that.

    And again and again, and again, IT IS NOT NECESSARY! ! !

    The bond we achieve with the common products is already perfect and all we need. There is no better bond than a perfect bond. One would just add more weight, but have no profit.
     
  8. Chris Ostlind

    Chris Ostlind Previous Member


    Perfect bond, Richard... really? Maybe you can describe the perfect bond to us as you see it, because industry has been searching for that state since man began his quest to put two objects together. The search goes on everyday in adhesive company chemistry labs all over the world.

    I can only wonder as to the smiles on the faces of the guys working their butts off in these labs when you march in all stiff and regimented and tell them that their jobs have ended because you said so on a boat design forum. Polite snickers throughout the room and a quiet call for the men in the white coats is made while you are gently guided to the exit near the loading dock.

    Epoxy is not a perfect bond for wood, Richard. Just put a typical wood strip canoe out on a black asphalt driveway upside down on a very hot day in the summer. Now put a weight on that boat after it gets to bake in the sun for a couple of hours and start telling us about how that bond is so perfect that it never deforms under load. Tell us that it never fails to maintain perfect integrity of the original glued shape. Tell us that high temps beyond the Glass transition temperature (Tg) are always higher than the service application of the part being glued. etc, etc.

    The typical, common resin used to build common boats has a Tg hovering somewhere in the 200 degree Fahrenheit region. Could you tell us how hot a boat hull sitting on the beach in Malaysia might get in the summer? How about that recreational stripper canoe that was just set aside at the YMCA parking lot and the forgotten about until a class of teenage kids came in from the lake to eat lunch and started putting a mountain of paddles on the canoe mid hull span? Still think it's a perfect adhesive? Still think that chemists all over the planet aren't working their days away trying to find new formulations to make it a better product?

    Trying to force products into absolute boundaries for the sake of conversation is going to lead you nowhere, Richard. For every one of these broad sweeping statements about specific products, there is going to be hundreds of instances where the absolutes can never hold-up as specified.
     
  9. apex1

    apex1 Guest

    Jaja, Chris.

    Have the last word...............

    After coming up with the Tg, which has absolutely nothing to do with bonding (and which can be raised to stand every common condition btw), you will come up with the next, if I would be dumb enough to reply.

    So, leave us idiots build our crappy boats with not deep enough penetrated timber, and too low a Tg point.

    Use diluents, thinners and solvents as much as you can and penetrate as deep the wood as you like, and be happy you know better!

    There is not one professional boatbuilder / yard in the entire wood epoxy scene in the world doing that, and we know why.

    But you know better..................
     
  10. Chris Ostlind

    Chris Ostlind Previous Member

    You're losing it, Richard.

    Further, you haven't answered the questions regarding epoxy as the product that makes a perfect bond.

    Really, the Tg value has nothing to do with bonding? Are you sure about that? Elevated Tg figures can be had, but not by common (that was your word for it, was it not?) boat building techniques. Now, if you want to haggle about the term common and look to include professional yards as "common" builders, I think that you'll have a lot of yards looking to distance themselves from your interpretation.

    Rather, I would suggest that the term, common, refers to the many, many thousands of everyday homebuilders who are constructing their own boats, do not have autoclaves, have never used vacuum bagging techniques and never will. That is the majority of the folks who visit these pages and will likely remain so.


    "So, leave us idiots build our crappy boats with not deep enough penetrated timber, and too low a Tg point."

    I don't recall ever saying that the penetration was not deep enough. If you can produce my quote on that topic, I'd love to read it. I believe that the general subject of penetration was raised and that, all by itself, it set you off on a rant.

    As to too low of a Tg value... well, I believe it was you who indicated that the product, epoxy, was a perfect bonding material. Common boat building resins which have Tg values in the 200 degree F range can be compromised and I indicated a couple of instances in which it would likely do so. You have offered no rebuttal of substance on those references and only more wandering and ranting.


    "Use diluents, thinners and solvents as much as you can and penetrate as deep the wood as you like, and be happy you know better!"

    I never advocated the above, Richard, I simply stated that it can be done, that it is being done by knowledgable manufacturers and that your comments were unfounded on the original matter as it was expressed on these pages.


    "There is not one professional boatbuilder / yard in the entire wood epoxy scene in the world doing that, and we know why."

    So, if I produce an example of a boat builder who is taking contract jobs and they are using the process, does that mean that you'll apologize on these pages for making such incorrect statements?

    Will you also apologize for saying epoxy is a perfect product for achieving a bond in wooden boat building if I have a chemist from a major epoxy manufacturer provide a quote saying otherwise?
     
  11. erikhaha
    Joined: Sep 2007
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    erikhaha Junior Member

    Wow, look what I started. Thanks for all your information. I checked out this link and test results:

    http://www.epoxyproducts.com/aluthane.html

    The aluthane sounds better than epoxy based on his test results as well as testimonialy from other people. Has anyone of you guys ever worked with this stuff?

    If not I will give the interior 2-3 coats of "unthinned" epoxy. Joints have already been reinforced, and I Always intended on reinforcing the joists, just didn't know if glassing the whole interior was worth it.

    Now would it matter if I painted the exterior pink or yellow? That is the real question.
    Oh, and Tom.151 thanks.
     
  12. apex1

    apex1 Guest

    I told you I will not answer on your drivel Chris!

    Instead of asking me to prove you wrong, ask the industry why ALL choose Epoxy when a perfect bond on wood is required in boatbuilding.

    You have had the final statement, leave it as it is.

    Back to topic:

    NO, a inner sheathing with glass is not necessary! period...

    Regards
    Richard
     
  13. Chris Ostlind

    Chris Ostlind Previous Member

    Thus Spake Zarathustra
     
  14. hoytedow
    Joined: Sep 2009
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    hoytedow Carbon Based Life Form

    Zarathustra sought the aša, or truth, so I guess if you meant that as an insult, you pretty much failed.
     

  15. Chris Ostlind

    Chris Ostlind Previous Member

    Hoyt,

    That's because you are limited by the literal sense. When one expands one's understanding on many levels, it hits the target with full force. Take some time, my friend, and do some reading on Nietzsche. It'll come to you.
     
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