HELP! Repairing 19' Lightning Sailboat

Discussion in 'Boat Design' started by FirstLight, Aug 26, 2012.

  1. FirstLight
    Joined: Sep 2007
    Posts: 75
    Likes: 1, Points: 8, Legacy Rep: 21
    Location: North Carolina

    FirstLight Junior Member

    Just for the heck of it I weighed the bare hull of my Lightning Sailboat and is was about 400 pounds over what it should be. 400 pounds! So a last I drilled about 50 small holes in the bottom to drain the water out and it dripped slowly for a week to give me about 20 pounds back of the 400. At that rate things were going to be slow going. So I decided to cut a couple inspection holes on the inside skin and through part the cockpit seat to see what was going on..

    Wow! About 15 cubic feet of 1970's foam thoroughly soaked. The 15 cubic feet were on one side of of the cockpit and that is all. So I acted like a crazy man and cut out one side of the cockpit to the outside skin. About 3/32" glass. There was 118 pounds of water soaked foam. Amazing! And that was in about 20% of the hull. I figure the other 300 lbs are to be had.

    I stopped there figuring any more cutting out would risk severe distortion of the hull skin. There is one 1/4" hollow and that is all if it is not messed with.

    How to go about it?? Photo attached. You can see the port side has been mauled and the starboard side intact the idea doing one side at a time to prevent distortion.

    I figured I would add horizontal stiffeners (of what I don't know and qty I don't know either) and then glass over. After that I would add frames from the side of the hull to the centerboard trunk one side at a time.

    Any thought on best way to do this. I thought of vacuuming a piece of new foam to the existing skin however that would cause a distorted mess (I think).

    Any ideas appreciated.

    I realize scrapping the hull and buying another with closed cell foam for $8k is probably a better way to go. However I'd like to try this on one side of the cockpit and see what happens..

    Thanks for looking..

    T
     

    Attached Files:

  2. FirstLight
    Joined: Sep 2007
    Posts: 75
    Likes: 1, Points: 8, Legacy Rep: 21
    Location: North Carolina

    FirstLight Junior Member

    Balsa Core

    Since I had some 1/2" scrim backed balsa at the house I'm going to use that as a core material and weigh it down with sand in plastic bags 2' x 4' at a time. Not ideal but since vacuum would seem improbable to use due to the flexible nature of the outer skin and would seem to want to pucker inwards I'll use weight.

    Using slightly thickened epoxy so I should get a good bond.

    Anything crazy I am missing here?

    Going to try it on one 2x4 section and see how it goes. Although I'm not sure how to tell how good of a bond I have between the outerskin and the core? Tapping perhaps? A couple small hole samples?
     
  3. JosephT
    Joined: Jun 2009
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    Location: Roaring Forties

    JosephT Senior Member

    Well, hats off for getting to the root of the problem. After you replace the deck be sure to encapsulate the balsa/core material really well with fiberglass so you're not starting again from square one.

    You might consider just replacing the deck and drilling some small holes to inject some lightweight, waterproof foam.

    e.g.
    http://www.aeromarineproducts.com/boat-foam.htm

    The old foam was obviously the wrong stuff and should have not been used. Your typical polyeurethane marine foam will be much better. You're looking for a lighter, non-structural, waterproof filler and this will do the job. Just fab a good strong deck & inject it...much less work. As it cures it will weep out of the holes. You'll have at least two holes (air vent + injection holes). I would space the holes out 12" apart going aft to forward. This will allow excess foam to bleed out as it cures. You can then just slice it off, lightly sand the deck, touch-up glass the injection holes, a coat of epoxy UV paint and you're all set for the water.

    Prior to doing anything though I would examine all areas under the floor to see where the leak originated...probably a crack some place. Fix that first, then hit it hard with the deck fab/injection.

    My 2 cents.
     
  4. FirstLight
    Joined: Sep 2007
    Posts: 75
    Likes: 1, Points: 8, Legacy Rep: 21
    Location: North Carolina

    FirstLight Junior Member

    Test Looks good. Now for greed.

    I did a 2'x4' test using 1/2" core material and it set up nicely using bags of sand for weights to hold the core material against the outer skin. I figured the sand only gave me minimal pressure (.1 psi). I might try to set up vacuum on the next piece to see if I can get a good vacuum clamp without distorting hull. Hard to believe this would work. Will try it.

    The next question is how much of the core can I remove at a time down to the outer skin before bad things happen. The deck is on which I would think helps.

    In a perfect world I would remove the deck and rip out all of the internal structure and existing core but I can't see the hull holding up without it being in a mold. Does this sound right?? The boat is sitting on a trailer in to athwartship cradles and that is all..

    Yes, this is crazy. Yes, this is time not well spent. But I'm learning heaps at relatively low cost right now.

    Any thoughts on how much of the existing structure I can remove to outerskin would be appreciated.
     
  5. FirstLight
    Joined: Sep 2007
    Posts: 75
    Likes: 1, Points: 8, Legacy Rep: 21
    Location: North Carolina

    FirstLight Junior Member

    OK..
    I think I'm updating this more for my own sanity than anything else. Spoke with one of the fellas at Gougeoun and they suggested adding supports every two to three feet to keep the shape somewhat intact. So this will be done.

    Going to try and supporting the bottom by building frames that brace against sheer instead of ground. Have seen it done a few times so we'll see how it goes.

    I figure I'm looking at $2000 in cost and 600 hours to do this. Right now I have a bit more time than money so it seems like something to proceed with cautiously and if it ever looks like an over the head project it will be abandoned.

    Anyone ever built frames supported by the shear instead of by the ground??
     

  6. JosephT
    Joined: Jun 2009
    Posts: 850
    Likes: 105, Points: 43, Legacy Rep: 218
    Location: Roaring Forties

    JosephT Senior Member

    Looked at the old wooden Lightning boats...they were built with frames for additional support. The fiberglass boats appear to just be a molded deck & hull that's filled with foam for floatation, which will also minimize oil can/flexing of the hull.

    You're on the right track with using some frames to stablize the hull during the repair. If you had a trailer for the hull the fore/aft wooden bunks should provide good support if they're built right. You could insert plywood slats that run fore/aft as well to ensure you don't have any crease points.

    You might also give a shout to the folks at http://www.lightningclass.org There are some used/repaired/restored boats listed there and I'm sure they can offer some suggestions for your project.

    I would also shoot http://www.nickelsboats.com an e-mail or give them a call and ask for suggestions. They likely built this boat (or know who did) and can recommend the best approach.

    Regards,

    Joe
     
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