Keel repair?

Discussion in 'Sailboats' started by Goingdef, Oct 21, 2013.

  1. Goingdef
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    Goingdef Junior Member

    [​IMG]

    Sorry for the duplicate pics, still trying to figure out my iPad for this type of thing.
     
  2. PAR
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    PAR Yacht Designer/Builder

    I've made this repair before and the area with the cracks is the hull, not just a filler. The hull shell wraps around, with considerable additional laminate, in this area and the liner follows closely inside, also being bonded to the hull shell. I believe the liner is ester bonded, while the ballast/hull shell interface is epoxy. John is correct the sump hasn't any bolts in it.

    I see a gap, not a big one and possibly just the irregular top of the ballast casting. It's difficult to tell with this photo. The real deal is to check the ballast for movement, which usually needs to be done in the slings, unless the boat has a stout cradle. An examination of the bolts usually will reveal any movement.

    This is the original H-40 (late 1980's - the keel shape is a dead give away) and these have been known to develop cracks in this area, most of the time cosmetic. I've seen them with a few laminate cracks like this, but the propagation of those cracks are typical of a strike, progressively getting more dense as they move aft. This is what happens as the keel cantilevers back in a bottom strike.

    Without checking the bolt torque, checking for movement and the gap at the top of the ballast, it's a tough call. Judging by the lack of a crack all or nearly all around at the ballast/hull shell interface, suggests not much movement yet, but it's still something you should check. One thing I've found on recent yacht purchases is, things like this tend to be covered up by an owner looking to hide some flaws. The usual fix is to grind out the crack a bit, fill with 3M-5200 and paint or fair over this (which is what yours appears to be) then paint.

    Check the bolts. There are two in front of the compression post, one more a little aft of this on the centerline and two more (side by side) around the companionway. Torque on those bolts will be 325 ft.lbs.
     
  3. Goingdef
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    Goingdef Junior Member

    So this area is not where the forward keel bolt is leaking from,could it be that they just need to be pulled cleaned under sealed and re torqued? And the area in question filled back around the border/bed with epoxy and the center mass area brought back out with glass mat and epoxy resin and paint?
     
  4. PAR
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    PAR Yacht Designer/Builder

    Your back fill picture apparently was posted as I typed the last post. That work looks good, though I would have taken the epoxy reinforcement around the corner a bit, up onto the hull shell stub with some biax and filler.

    Check the bolts. The keel bolts that get stretched in a bottom strike, are the forward most. When the keel gets to relax after you're off, you can get slack in these bolts, which can start a leak. After 20 - 25 years, the bolts surely need to be checked for torque and good bedding.
     
  5. Goingdef
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    Goingdef Junior Member

    What would you suggest I use to fill this area back in? Would a good gun able two part epoxy over the old epoxy bed work, then fiberglass mat and a marine filler to bring the area overall back up to flush with the keel then sand and repaint? Then re torque all the bolts to spec?

    Also sorry for the ignorance but what's biax?
     
  6. PAR
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    A spray gun wouldn't be recommended for this small a repair. I would bulk up the area with fabric, until just shy of the surface, then use a fairing filler to make it smooth. That's a big divot there, so you might as well put something meaningful in there.

    Biax is a knitted fabric of two layers of unidirectional fabric, commonly at 45 degrees to each other. It's stronger then cloth and roving, because the fibers lay over each other rather then weave through each other. Mat is chopped 'glass fibers with a random orientation. Think of this as particle board, compared to plywood. Mat has no real strength and is just a bulking agent. In this situation, the use of mat can save some time and layers of laminate.

    Tighten the bolts first, then finalize the hull repair, so that any movement from the bolt tightening doesn't screw with all the fresh goo work.

    Any fairing compound will do once you've bulked up the area within say a 1/16" shy of the surface. Very often in this area you'll see quite thick hunks of fairing compound, but these tend to crack in time. The more you can bulk up, the less you need to smooth things out and the longer it'll last.
     
  7. Goingdef
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    Goingdef Junior Member

    Thank you very much for your help I'm going to start exactly what you said tomorrow afternoon, are there any specific epoxys or resins I should be using or will either or work?
     
  8. PAR
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    Any marine grade epoxy will do, though costs can vary widely. QuickFair from System Three is easy for the novice to get good results. It sand s easily and is smooth stuff to work with. I make my own fairing and filler compounds, but you don't need to go to this trouble. There are several places on line to get supplies. Check out Progressive Epoxy Polymers at epoxyproducts.com (ask for Paul and tell him PAR sent you) and also check Bateau.com.
     
  9. Goingdef
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    Goingdef Junior Member

    By chance is west marine decent, I believe my dad has an account there and there would be no wait time for shipping. But if not I can contact the guys you suggested.
     
  10. PAR
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    PAR Yacht Designer/Builder

    West Marine is a retailer specializing in marine products. They probably charge more for supplies than anyone else. They carry a lot of products and overhead, so you have plenty of choices and pay a huge markup. I buy epoxy in bulk for about $40 a gallon, but you can get the exact same stuff online for about $60 a gallon. You'll pay over $100 a gallon at West Marine - it's your choice. Epoxy and 'glass supplies can be shipped through regular mail or through UPS/FedEx. In many places shipping is free, if you order over a certain amount.
     
  11. Goingdef
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    Goingdef Junior Member

    I was only thinking of shipping in the delay it's already $25 a day at the yard so even with three day shipping for free it still cost him in wait time, but it won't hurt to price them then do some math and save a buck where I can!
     
  12. PAR
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    PAR Yacht Designer/Builder

    Yep, lots of folks use West Marine just for the convenience. You don't have to bow your head, unless someone sees you coming out with a shopping bag . . . :)
     
  13. Goingdef
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    Goingdef Junior Member

    Ok after west marine got done applying the "****" we are ready to start tomorrow I have plenty of glass mat a gallon of epoxy a slow set hardener and the fairing filler and all the tools I should need. I was using a sketch app and figure I can lay a narrow strip in the bottom where it's deepest and work out with progressively wider strips until it's almost flush since the whole thing tapers up to the hull and finish it off with the fairing compound? Sound about right!
     
  14. PAR
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    Yes, though I'd use a combination of cloth and mat. Mat has very little strength, but improves bonds to irregular surfaces, like what you have. So, the first layer would be a mat and I'd use this across the whole of the recessed area. I'd follow with cloth, probably a few layers, then more mat so the secondary bonds will have some "tooth" to grab. I'd continue with the alternating mat/cloth routine, until the area was just shy of the surrounding surface. The last layer would be mat to prevent "print through".

    Technically you don't need much strength, but any cracks will propagate through a weak laminate, meaning you'll have to do this again. If you use a mostly cloth or biax laminate, you resolve these issues. I use mat only to improve bond on rough surfaces and to prevent print through, as it's weak and just a resin suck pig of a material.

    Of course torque the ballast bolts up, before doing this. You'll get it, work slowly and neatly, to save yourself trouble later.
     

  15. Goingdef
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    Goingdef Junior Member

    Thanks for all your help, I have plenty of woven cloth too so I will follow the steps you laid out and yea I am going for as neat as possible to save myself some sanding that's why I went with the 20-30 min set time hardener, do I attempt to do all these layers at once or let each one tack up before starting the next?
     
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