Is this right? (foam)

Discussion in 'Boatbuilding' started by CatBuilder, Feb 16, 2011.

  1. gonzo
    Joined: Aug 2002
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    Location: Milwaukee, WI

    gonzo Senior Member

    If you have a huge difference in bog between hulls, there will be a weight difference. The boat will list.
  2. CatBuilder

    CatBuilder Previous Member

    I know. I'm looking at probably a a gallon or two of extra bog on the starboard hull. Not too bad...

    It only took about a gallon of bog to fill in the entire hull's gaps... and these are tiny imperfections I am filling in after a sanding.

    Hey, welcome back to the States! Must be culture shock coming back after spending so much time in GB.
  3. SeaJay
    Joined: Jun 2007
    Posts: 211
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    Location: Sacramento

    SeaJay Senior Member

    Cat Builder - I'm kinda-sorta following your technique and am not sure if the following applies but I'll throw it out just in case...

    I don't have the same situation as yours, but have had to attach 1" foam in a similar manner and am using composite nails/staples with an air need to remove screws and fill holes. Fast, secure, (and somewhat expensive) Again, not sure if it is applicable to your build but you might keep it mind.

    Best Regards,

  4. CatBuilder

    CatBuilder Previous Member

    I like the sound of that, SeaJay... thanks.

    Are you nailing into a wooden batten behind the foam? If so, how are you not removing the composite nails?

    Just trying to figure out your technique. Thanks for posting.

  5. SeaJay
    Joined: Jun 2007
    Posts: 211
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    Location: Sacramento

    SeaJay Senior Member

    Cat - I added about a foot to the top of the shear line on an existing composite hull. Sort of hard to explain the details as it is strictly a one-off deal, but I had 1/8" ply over battens in a "female" type of configuration. I nailed from the inside of the boat through the foam into the plywood. I bought a special air gun made to handle the composite nails. It took a small amount of trial and error to determine the correct air pressure so that the nails had the proper penetration. They hold amazingly well.

    I am leaving the form work up until the bulkheads are in place, but afterwards, I'll strip off the ply from the outside and just grind off the nails where they protrude through the foam. You just need to touch them with the grinder and they disappear. The nails are frightenly expensive but for what they do, they are well worth it. The foam pulls down tight and you know how fast you can work an air gun...bam, bam, bam, and twenty nails (brads) are in place.

    Here is a link to the place where I get my supplies...

    Somewhere on the web there is a site where a guy did a strip plank cold molded ply hull using these nails. I'm not in my office so I don't have the link, but if you are interested and can't find it with a Google search, let me know and I'll see if I can find it when I get home. He used a ton of the nails... lots more than you or I would probably need, but it gives you a pretty good idea of how you can really force a compound curve into sheet material. I used 5 lb Core-Cell which i belive is what you are using, and it holds the nails really well. I was really pleased at how tight the foam pulls to the ply.
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