1959 Penn Yan Maggelan - Fairing the hull?

Discussion in 'Wooden Boat Building and Restoration' started by gillam77, Feb 28, 2012.

  1. gillam77
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    gillam77 Junior Member

    1959 Penn Yan Magellan -Lapstrake oak on mahogany
    Project Requirements
    Structural
    1. Remove a thought-less previous repair. Were a piece of plywood sandwiched foam in a can against a three inch puncture to the hull;
    2. Replace all ribs;
    3. Remove the first layer of laminate of plywood planks (due to rot) and epoxy veneer to entire bilge;
    4. Replace gunwales;
    5. Render repair to transom (someone had chopped the transom enable to attach a short shaft engine);
    6. Replace the bow stem;
    7. Install a teak and holy deck; and
    8. Rebuild the entire interior.

    Project Status
    History

    1 thru 5 are now 100% complete. We are currently laminating the new stem.

    While this is being done I am also looking to prep the outside hull. There are thousands of buns at this point, a few repairs of veneer (on the exterior) and the hull is just generally uneven. The interior of the hull at least the bilge, is coated with wood sealer and has epoxy based fillets along the lapstrakes.

    Questions

    1. What product can I use to skim coat the bottom to be later fair out? The concern here is that the current surface doesn't fair evenly with all the bungs etc.

    2. All of the ribs have been replaced so almost all of the fasteners along the lapstrakes have been replaced. The remaining fasteners I intend to leave as is. What is required to prep all of the seems along the lapstrakes? It seems like it would be weeks to remove all of the 5200 (or whatever like product was used in 1959) and reapply. Some areas are clearly in rough shape, others not so clearly in rough shape. What can be done short of spreading these joints and trying to inject 5200? And what product should be used?

    3. Once the outside of the hull is faired, what products/ series of products should I use? This boat will not be getting anti fouling paint. Wood sealer followed by epoxy based paint? Also, as this rebuild still has a long ways to go, what coating stage can the bottom be left at until the final coating is applied?


    Thanks in advance for your time and knowledge.
     
  2. gillam77
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    gillam77 Junior Member

    anyone?
     
  3. PAR
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    PAR Yacht Designer/Builder

    It's pretty tough asking for advice when you've used this approach. Typically, the seams are opened, cleaned, then rebedded when refastened. This would have been fairly easy, done traditionally, but now that you've removed 20% of the longitudinal stiffness of the planking (no outer veneer on the planking), prying open the plank laps may not be such a good idea.

    Nothing is used to "treat" the seams. The seams are bedded in polysulfide, then fastened closed. If you have leaks, then you have to open the laps, clean them and apply more bedding during the refastening.

    Your approach is a bit odd and what to do, that might actually work is questionable. If someone brought me this boat, My recommendation would be to pull the planks and rebed them. Given they've had their outer veneers shaved, I'd personally pass on this job, knowing the planks are considerably weaker now.

    Epoxy is a wood sealer and should be used alone, though honestly, you don't need it on a traditional lapstrake build. If you must, 3 coats of epoxy on the outside will seal up the wood better then anything else.

    As to the fairing compound, you have two choices; pre-mixed fairing compounds like System Three's "Quick-Fair" or you can mix your own, using epoxy and light weight fillers, such as micro balloons, Q-cells and/or micro spheres. Don't even think about automotive body filler (Bondo), which has no place on a boat.

    Lastly, these traditional lapped boats are something I work on a lot and fully understand. Fasteners and lap lands are the biggest issues these boats face. Because of the number and general size of the fasteners, it's really easy to have several dozen causing problems. This is why you always replace all of the fasteners in a plank, not just some. Invariably, the ones you leave that looked good, will loosen up and cause problems, so it's better to start with a level playing field, so if you do have a problem later, you're not guessing which fasteners where replaced and which weren't.
     
  4. gillam77
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    gillam77 Junior Member

    Thank you PAR. Forgive me as I am clearly a novice yet. This boat is mahogany plywood on oak frames. The entire inside of the hull below the waterline has had the top laminate of the plywood removed and new veneer laminated through out. At the chine a few of the lapstrakes were damaged thus a few spots on the exterior have veneer patches.

    There would only be about 10 % fasteners remaining so I will go ahead and replace them all. None of the lapstrakes other than adjacent bow stem have ever leaked. Hopefully having the entire hull refastened, new fillets on the interior and three layers of epoxy on the outside will prevent any problems in the near future.

    Thanks for the advice.
     
  5. gonzo
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    gonzo Senior Member

    Why did you remove all the frames? Epoxy is a rigid adhesive and doesn't work well with the flexible polysulfide. Are you saying, you took a veneer off the plywood and then glued a new veneer on?
     
  6. gillam77
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    gillam77 Junior Member

    Every other rib was replaced followed by the other half so as not too lose any shape. While this was being done one laminate of the original plywood was removed and replaced within the entire bilge. The boat is certainly as strong or stronger than original.

    The rabbit joint of the new stem is just about complete. We should be installing the new bow stem next week. It is 9 laminates of mahogany epoxied together.
     
  7. gonzo
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    gonzo Senior Member

    How did you glue a continuous veneer to the planks?
     
  8. gillam77
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    gillam77 Junior Member

    Maybe I'm not using the proper terms...

    The boat has plywood planks? or strakes? (Its lapstrake construction mahogany on oak) The laminate was veneered in pieces as large as possible between the ribs (only every other was out at any one time) Then the rest of the veneer once the other half of the ribs were out.

    We have a former employee of Brooklyn Boatyard working on the project part time.
     
  9. PAR
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    PAR Yacht Designer/Builder

    The plywood planking on your boat, gets the majority of it's strength and stiffness from the continuous veneers, running the length of the plank. If you cut this up into little sections, then the plank is dramatically weakened. Generally, planking is replaced after a while, depending on service. It's a consumable item, just like an oil filter. When it dies, for what ever reason, it's pulled and replaced. This said, it can be repaired too, but typically with lengths of good plywood, scarfed or butt blocked in place of the damaged areas.
     
  10. gonzo
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    gonzo Senior Member

    I have never seen anything done like that. It may be a candidate to fiberglass over. You can fill the edges of the laps with wood molding and then fiberglass over.
     
  11. gillam77
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    gillam77 Junior Member

    whats done is done right. not sure if you are familiar with Brooklyn Boat Yard, fairly good reputation for wooden boat construction. They thought the veneer wasn't really necessary. They seemed to think it will add strength and certainly look amazing. Unlike other boats this one has ribs every 3 inches too.

    I would never glass over such a thing. That should be a crime.
     
  12. PAR
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    PAR Yacht Designer/Builder

    So basically what you're saying is you have the inner, longitudinal veneer, sliced every 6" along it's length, where the patches have been applied?

    Lets assume you have a 5 veneer 3/8" planking. 1/3" of the longitudinal stiffness has been compromised, but you think this is okay? The BBY has a good reputation on traditional approaches to repair, which I don't think this qualifies.
     
  13. gonzo
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    gonzo Senior Member

    The question is why the helper is a '"former employee"
     
  14. PAR
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    PAR Yacht Designer/Builder

    I don't think it's important that he's a former employee, especially in these economic times. I'm a former employee of several companies myself, which says nothing about me except possably some experience.

    I'd like to see some pictures of the veneers, patching the inside of the planking if possible.
     

  15. gillam77
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    gillam77 Junior Member

    Its 1/2" and in 1959 plywood or at least this plywood has what look to be 8 veneers thick of which are much thinner then was replaced.

    Only the two planks below the turn of the bilge have seen this repair. Every other frame goes from gunwale to gunwale. That said, the sheets veneered in were at minimum 12" wide.

    The current shop manager at Brooklyn has been the consultant for this job as it is his son that is the shipwright doing the work.

    They actually showed us the equation for the strength of plywood for each additional veneer. I can't seem to find it but it was not a straight line equation. That said, I find no need to further defend their methods. Other professionals that have come to see this project have not questioned their methods.

    Thank you for your concern though. We are all confidant this boat will be as strong as the day it was first launched.

    My original post was just to seek advise on how to fair the hull while my employee was away for the week on vacation. I should be good now.

    Thanks again.
     
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