Keel repair question on 16' sailboat restoration.

Discussion in 'Wooden Boat Building and Restoration' started by OrcaSea, Apr 30, 2015.

  1. OrcaSea
    Joined: Oct 2014
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    Location: Arlington, Wa

    OrcaSea Senior Member

    So. Flipped and stripped the boat. I knew I had some rot issues with the keelson, as the fiberglass had been broken and I could see some rot underneath, so I removed the section of keelson that was bad.
    [​IMG]

    Evidently, the original builder over-tightened the keel bolts that extend through the keel and through the bedlog and cracked the keel (I wondered why some of the bolt tails were longer than the others - now I know).
    [​IMG]
    [​IMG]
    The original builder filled in the cracks (I pried out the filler material) and even tried to drive a few lateral fasteners through the cracked section and drove on.

    The boat drawings were released in '58 and I am assuming it was built within a couple years of that, so it's persisted in this condition for a long time.

    I need advice: Does it make sense to cut out the rotted section and splice in new wood? Seems like a silly question, but with short edge margin on the fasteners, difficulty of access and back-drilling the keel bolt holes accurately, etc., while it might look a lot better and make me feel better, is there a structural advantage to doing so beyond filling with goo and machined fibers and strengthening it as much as possible in situ? Meaning, will a splice actually carry whatever loads it needs to through the bolts/bedlog/etc., without just cracking off again, anyway? The rest of the keel outside of the cracked area is surprisingly solid and the cracks have not caused any deformations, etc., elsewhere. I guess I already know the answer to the question, but what would be the best approach as I have limited access to the area, over all?

    The keel bolts all need to all be replaced, as they are pretty corroded. Plus, the centerbox interior needs to (somehow) get stripped and re-glassed (any tips for that job would be appreciated, as well).

    Curtis
     
  2. messabout
    Joined: Jan 2006
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    Location: Lakeland Fl USA

    messabout Senior Member

    Curtis; it depends on how much you value the boat or how long you intend to keep it. If you just want to get through the summer and then give it a decent burial, then you could dope up all those cracks with epoxy and milled glass fibers or other filler and call it good.

    On the other hand if you want to preserve the boat, I'd think in terms of replacing that section of the keelson or maybe the entire thing. It appears that the distress is around the centerboard case. You may end up building a new case and then you need not worry about the interior of the old one.

    Take some pix of that area from the inside of the boat.

    Because the boat was built back in the dark ages things were glued up with resorcinol and bolted together. We might not do it that way these days. We have epoxy now. In the 50s it was around but had not been widely used as an adhesive because it was still a new chemical that had not been so keenly developed as it is now. The point is; Why do you even need those bolts?
     
  3. OrcaSea
    Joined: Oct 2014
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    OrcaSea Senior Member

    Thanks for your input, Messabout. You've made some good points and it's always appreciated!

    Crawled under and took a pic of the keel/bedlog (you can see the filled bolt recesses in the bedlog) and centerbox (lower portion of pic).
    [​IMG]
    Everything on the cockpit side is solid, good wood. I haven't got out my 6" scale and measured the damaged area and where it lies with regards to the bedlog on the cockpit side yet.

    Surgically removing the damaged part of the keel with an oscillating tool wouldn't be difficult, but right now I am feeling that removing the ply bottom and that entire section of keel is beyond what I want to tackle. But there must be a compromise that will work and last for at least a few years; I have a LOT of work into it and hope to enjoy it for a while. It is a fair-weather daysailer and not an ocean racer, after all.

    I agree about re-building the centerboard box - trying to strip and re-glass that with any integrity would be a FAR bigger PITA than rebuilding it, but the centerboard box is rabbited into the bedlog and there are no external fasteners, so my concern is that they were fastened to the bedlog from the inside before assembly. I could cut/chisel the centerbox sides out of the rabbit but can't imagine (yet) how I would reclamp the second half of the new centerboard box sides into place. Maybe tapered shims through the centerboard slot...hmmm...

    The external keelson was only about 3/8" to match it up with the bottom ply, but I would likely make the new keelson section thicker, probably at least 3/4" and fair it in - I don't mind the mismatch and it would act as a sister to the damaged keel section.
     
  4. messabout
    Joined: Jan 2006
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    messabout Senior Member

    The pix do not make it entirely clear about the interior but from what I see it looks good.

    That the outer keel is let into the surface ply is Puzzling. Not the way I would have built my boat but...very well different strokes for different folks. If you have rot or soft wood in the pictured distressed areas the fix might be problematic. On the other hand if the wood is sound in and around the fractures, there is hope. You could fill the damaged areas with epoxy and then install the outer keel, as you say at 3/4 thickness. That will hold the whole keelson in place with some confidence that it will stay in place. I see no need for bolts. If the epoxy lets go the whole deal is off. It won't!

    When letting the keel into the space between the ply panels, some care should be used. Glue the whole external plank to the internal one with some epoxy goo and you'll likely have a sufficiently rigid structure to last a long time. Where the sides of the external plank meets the edges of the ply skin is a potential trouble spot. Fit it carefully and with sufficient epoxy to seal the ply edges and seal the tiny gap between the two elements.

    The little boat appears to be worth saving. Its' bottom looks a little bit Snipe like. But a lot of boats of that era looked similar to that one. I am going to guess that she is on the heavy side but that is not all bad.
     
  5. OrcaSea
    Joined: Oct 2014
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    OrcaSea Senior Member

    Thanks, Messabout.

    I have put about 9-months of work into the boat, thus far, so failure isn't an option at this point.

    I am starting to think the same way. The wood around the splits is in surprisingly good shape. So much so that, frankly, I am surprised. It makes me wonder if a preservative wasn't used...

    At any rate, I am starting to think that any slicing & dicing should be kept to a minimum as I could weaken the structure unnecessarily, or beyond what I can reconstitute with epoxy bonds. I might remove the damaged wood and install a splice; something for the external keelson (I'm new to this and the online references seem to call any cap over or under the keel a 'keelson'?) a good surface to adhere to. But I will take great care to ensure the wood is encapsulated and sealed up well.

    Don't think it is evident in the very first picture, but there was quite a gap between what I am calling the keelson and the bottom ply that was filled with wood putty. I will try and keep it to a minimum the next time around.

    Thanks for the reply and support. I am finding that getting good feedback and letting this stew in its own juices in the back of my head for a while seems to be helping in developing an approach to the repair.

    C
     
  6. OrcaSea
    Joined: Oct 2014
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    OrcaSea Senior Member

    I've decided to remove the centerboard box and bedlogs and re-build that entire area. The more I've gotten into it the more I realize I just cannot let myself do this half-assed (it's full-assed, or nothin'!) This will allow me to repair the keel and plug the holes and bring some integrity back to the structure.

    Ah, me. What have I gotten myself into? It's the journey, not the destination, right? :)

    C
     
  7. Petros
    Joined: Oct 2007
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    Petros Senior Member

    That center lumber looks massive, much larger than it needs to be. More modern designs use much lighter lumber for the keelson. If it is not rotten, it should have plenty of strength.

    I would replace the big fat fasteners with some smaller stainless steel ones, fill the gaps and holes with epoxy fillers, and cut a wood keel to fit tightly into the space between the edges of the plywood skins. Bond it into place using small screws to hold it down tight until it cures, and call it good. just make sure it is sealed up well so there are not places for moisture to be trapped inside the build up.

    Pulling it apart that far might weaken the hull unless you start replacing the skin plywood as well. If it is structurally sound I would just leave it in place.

    I think about you sometimes and keep meaning to drop by, I have had a real busy work schedule so likely just as well for me, or I will get even further behind. Perhaps I can swing by on Friday if you will be around, work is only a few short blocks away, and see it in person.
     

  8. OrcaSea
    Joined: Oct 2014
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    Location: Arlington, Wa

    OrcaSea Senior Member

    Yeah, it seems to me an odd design, though I am certainly no boat designer/builder. I have always thought of a 'keel' as being a single, heavy monolithic structure around which other structure is built, but on this boat what he calls the 'keel' in the drawings is probably more aptly a keelson, and the supporting structure - which changes throughout the length of the boat - makes up the greater part of the 'keels' strength.

    At any rate, the more I got into it (I knew the centerboard box had to be re-built, so out it came) the more I realized that I was going to have to rebuild the entire area. There were just too many issues with the Resorcinol having long-since given up any adhesive properties, leak issues, etc.. So the (what the drawings call) bedlog and centerbox have all come out. Still considering whether to slice out the bad areas of the 3/4" "keel" or just embed them and sandwich them in the stronger supporting structure.

    What I am going to need soon is someone local that can do some simple millwork for me; I don't have a table saw or band saw, and I am going to need some rabbeting and match cutting on the curves of the bedlog, etc., all for as reasonable a price as I can manage. Do you know of anyone local that can do that?

    I am working today in Tacoma, but hope to be back around home by 1:00, or so. Love to get a second set of eyes on things and meet up in person. It's looking a bit rough as I just flipped it and stripped the old FG off.

    Curtis
     
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