Petrel - My first boat! (Yes, I have medical insurance)

Discussion in 'Boatbuilding' started by knightyo, Oct 16, 2011.

  1. knightyo
    Joined: Oct 2011
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    knightyo Junior Member

    That was extremely helpful. Thanks. I'm on my way to Hope Depot right now. :)
     
  2. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    TiteBond II isn't waterproof so it's use should be saved for elements that aren't anywhere close to high moisture content.

    I'm not sure which "test" you were reading, but it obviously wasn't a by a respected industry leader or other recognized facility, in regard to marine adhesives. In short, holding frames together with an non-waterproof glue isn't exactly a wise choice. TiteBond II passes the type 2 test, but not the type1. TiteBond III does pass the type 1 WBP test, but just barely and does soften considerably (and weaken) if immersed or consistently wet. Lastly, these are PVA's and not considered structural adhesives (mostly because of creep), so again, consider the physical properties of the adhesives you're employing. If you want to stick a fiddle to a shelf, then both versions of this PVA will work fine, but if you want to rely on an adhesive bond in a structural application, you may want to consider a different goo.

    Brass screws also are a poor choice for marine fasteners. They break down pretty easily (corrode) and have very low strength to yield qualities.
     
  3. LesPetrel
    Joined: May 2012
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    LesPetrel Junior Member

    The tests were on white oak and when the wood fails before the glue joint I consider the glue more than adequate. And if it stays wet, yes epoxy is better. This is a trailer sailor and won't stay wet all the time. If I were leaving it at a mooring I might agree with you. Since I'll be sailing in fresh water, brass is plenty strong enough for this application, especially since it is functioning more as a clamp than a sole means of restraint.
     
  4. PAR
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    PAR Yacht Designer/Builder

    Okay, so you don't qualify the tests or list the physical parameters and your understanding of brass in wood, in a marine application is well, clearly different than the rest of the industry. What type of brass was it? Yep, good luck with that . . .

    Knightyo, you'd be best advised to use accepted practices, rather then off the cuff recommendations.
     
  5. LesPetrel
    Joined: May 2012
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    LesPetrel Junior Member

    Ah, let me guess, you're with the know all see all restrict all government. Right?
     
  6. knightyo
    Joined: Oct 2011
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    knightyo Junior Member

    Had a windstorm roll through and do some considerable damage last night, so didn't get a chance to go to Home Depot. Sounds like that was ok tho, if Titebond 2 isn't the ideal way to go. I can see both of your arguments; that is the beauty of these forums. Exchange of info, even if ppl disagree w/ each other.

    In theory, my boat will be strictly for small, placid freshwater lakes, but I'll go ahead and stay with the resin in order to be on the safe side.

    I seriously appreciate your feedback, guys!
     
  7. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    No LesPetrel, I'm with the appropriate products, that display the physical properties desired, for the tasks at hand camp. No one I know (in the industry) would ever suggest common brass as a structural fastener in a boat, even if backed up by a glue, unless the glue was epoxy. Speaking of glues, no one I know would recommend a non-waterproof glue in the frames of a boat, dry sailed or not. It's just common sense and if you have issue with it then great, just don't venture farther from shore then you care to swim back to.

    There are some alloys of brass that can be acceptable, but these aren't very common. This is why I asked which type of brass you have, mostly just trying to find out the zinc content. I'll guess you didn't know it had zinc in it, let alone it was an alloy. I'm not trying to insult you. Why would you need to know these things, as a casual builder. On the other side of this coin, are the developmental tests and technique upgrades, the industry incorporates and regularly employs. You wouldn't necessarily know about these either, except that the "these usual suspects" are chosen for a reason (typically more than one), which is commonly available.

    The same is true of the adhesive choice you've made. I know precisely what it can and can't do, which tests it's passed and it's physical properties. And again, there are applications for a type 2 PVA, but not in the lower frame futtocks and gussets, even if backed up by inferior brass fasteners.

    If you want to debate it, fine, but know your materials and products when you do.
     
  8. Petros
    Joined: Oct 2007
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    Petros Senior Member

    The brass screws they sell at hardware stores are not very strong and turn to mush when exposed to the elements for very long, not recommended. there are painted deck screws they sell at hardware stores that are guaranteed not to rust or corroded. I have used these for small dry storage boats with good success, and lots cheaper than stainless fasteners. Bronze screws from a marine supplier, bought in bulk, are a better choice and also less expensive than stainless.

    I have also used Tightbond II and III for small boats, and again if the boat is not stored in the water, for most joints it works fine. However for critical structural joints, epoxy is the way to go. In most applications for boats stored out of the water and the weather, the water resistance of the Tightbond II is good enough in a small boat. It is cheap, easy to use, not toxic and easy to clean up.

    I think however, if I was building something larger than a dinghy, I would go will all epoxy only because the time and materials investment is so much higher it is not worth the small savings in adhesives to justify using Tightbond III.
     
  9. locksafe
    Joined: Apr 2009
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    locksafe Junior Member

    I would like to know if using dowels set with epoxy and covered with epoxy would be acceptable for putting the frames together. I have never seen it done but would like to know if it can be done and if not , why not ? i am certain that a 10 mm thick dowel would hold better than a screw of just about any size - if there is anyone on this forum with knowledge about this , i would gladly like to hear from him (or her)
    thanks , Hannes
     

  10. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    You're incorrect to assume the dowel will be superior to a screw, even with the epoxy bond. In shear and in pullout strength, the dowel simply isn't as tough, as the common metals used in wooden frame assemblies. Now I use dowels all the time, but typically for insuring pieces remain aligned during assembly.
     
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