hello i have just got a 41.5ft wooden seaplane tender with a bit of rot. i entend....

Discussion in 'Materials' started by captaingossy, Feb 24, 2009.

  1. captaingossy
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    captaingossy Junior Member

    to remove the rotten plank of cedar wood replacing with new one. then i have some mad ideas as of what to do next but before i get carried away. what should i do next sanely? expoxy the thin gaps! or i was told there was a lead like subtance i work into them. then i was told to marine ply it. and seal it with antifouling. what is the best expoxy's on the market and how much would i need to coat the under side of a 14.5 ft by 12.6ft vessel. plus a rough cost if possible. i am based on the river thames near windsor in the uk and am total new to all this. but have a crazy idea to get to the marine ply stage and steel plate metal clad the whole thing to make almost bullet proof or maybe kevlar whatever you got to watch out for pirates on the high sea's espeacilly as i want to be one when i grow up aaargghh.........!:confused: but :cool:
     
  2. PAR
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    PAR Yacht Designer/Builder

    It's generally much less costly to repair the planking (very likely more then one is affected) in a traditional fashion then cobble up some hair brained repair.

    If you've not worked in these venues before, you should stick with well proven techniques and find some help from a skilled boat carpenter.

    This is because rot is never an isolated thing, it spreads like a flu virus and gets into things you haven't uncovered yet.

    The only way for sure is to get the boat on the hard, and have a very careful examination. This requires a fair amount of skill to perform with some level of accuracy.

    Pictures would be helpful at this point.

    All the major epoxy formulators produce similar products, no single one is hands down better then the others.

    Log onto their web sites and down load their user's guides to get an idea how to work with these miracle goos.
     
  3. mydauphin
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    mydauphin Senior Member

    Pictures would be helpful, after that we can give some good advise. Should not be a big deal...
     
  4. captaingossy
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    captaingossy Junior Member

    here are some pictures

    all help would be grateful and useful. thanks
     

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  5. captaingossy
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    captaingossy Junior Member

    another picture

    i can only upload two
     

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  6. PAR
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    PAR Yacht Designer/Builder

    Interesting way to use batten seam construction. You have several options, though I think you have more bad planks then the photos show, particularly along the LWL.

    Plywood is an option, so is replacement planking of cedar.

    The seams on this type of construction usually don't have anything more then an oil based seam compound in them. The fasteners pull the planking down tight against the battens, which seals them up. If they leak, it's almost always because fasteners have loosened and the planks have begun moving.

    Repair the fastener holes, by drilling them out and gluing a correct size dowel in place. This restores the frame or batten to original integrity. The dowel stock should be the same wood species or one of similar physical properties.

    The traditional way would be to use new cedar planking, milled to the proper thickness. These would be cut to fit and attached the same way as the old planks with new fasteners.

    You could also use plywood, cut to fit the separate planks areas, or it looks as though you may be able to "bridge" a few battens with a single piece of plywood. This would save time and would strengthen the area, plus you'd have less seams for potential leaks. This also isn't a traditional looking repair. The lack of seams in these areas will stick out like a sore thumb (you could score the plywood to simulate the seams), unless you can smooth the other seams down nicely. Then again you may not care all that much about a few repair areas, so long as it stays dry.

    Have a good look at the hood ends of the bottom planks (which look file planked) and also the chine log. Again looking for loose fasteners, rot, damaged wood, etc. Fix any bad fastener holes, refasten, etc.

    Now for the seam goo. There are a few different products you could employ. I'd recommend you use polysulfide on good, clean seams. 3M 101 is the brand I use, but there are others. Polyurethane will work too, but the seams have to remain under tight pressure (from the fasteners) until cure is complete (about 30 days) and the seams have to be very clean and dry. An oil based compound, such as Dolfinite or similar can be used too. It hasn't any adhesive abilities, but will remain pliable for decades. It will not work if fasteners get loose, but it's a traditional compound that works well.
     
  7. mydauphin
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    mydauphin Senior Member

    What are you plans for boat? Do you want a quick fix, a restoration or something long term? How bad is the rest of the boat? I can give you three different ideas but dont know if you want to fix it quick, well or best.
     
  8. captaingossy
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    captaingossy Junior Member

    thanks everyone. i would like her to last as long and as tough as humanly possible as she quite rare now. plus i want her sea worthy in rough sea. i haven't quite got her yet but i should be bringing her down soon from up north and have only seen her once so i am not sure of her ultimate condition. i got more picture but there seems to be a limit on how much i can up load.
     
  9. PAR
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    PAR Yacht Designer/Builder

    Obviously a comprehensive survey is in order before purchase.
     
  10. mydauphin
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    mydauphin Senior Member

    " i want her sea worthy in rough sea" - Be very careful... Honestly, I believe the best way to make wood boat seaworthy is to cover it in fiberglass. I may be prejudice against it but I couldn't sleep at night in the middle of the ocean in a wood boat made from little planks that could be eaten, leak or fall off...
     
  11. PAR
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    PAR Yacht Designer/Builder

    As you may have surmised from the majority of repair and restoration folks here, 'glassing over your hull isn't a wise idea in terms of longevity, resale value, repair or maintenance. The only time I would recommend this treatment is if the hull was at the end of it's serviceable life and a thick 'glass sheathing applied, which could provide some additional seasons of service.
     
  12. captaingossy
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    captaingossy Junior Member

    how about layering up the hull for example repair the cedar planks fill the seams next a layer of fibreglass then a layer of ply and to finish an antifouling paint or on top of the ply a layer of sheet metal maybe aliminium followed by paint it would add weight but surely strengthen her up quite a lot. or on top of the ply is there other materials i could add. i heard kevlar is sometimes used mixed iwth fibreglaas to toughen it up for a longer service life. thanks in advance
     
  13. captaingossy
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    captaingossy Junior Member

    this might help

    a few more pictures
     

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  14. captaingossy
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    captaingossy Junior Member

    a few more

    pictures
     

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  15. PAR
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    PAR Yacht Designer/Builder

    Your additional layout of materials isn't logical as you've listed it.

    I don't think strength is an issue, but sealing up the leaks and making repairs to damage are.

    You could do both with a skin of thin plywood over the whole of the exterior, which would then get 'glassed and painted. This will add weight (make the boat slower, require more fuel to propel and cost more to do), but it'll seal up the hull quite well.

    Of course for this to work as best as it can, the damaged areas need to be repaired, any structural repairs made (broken frames, etc.), a bunch of plywood screwed down to the old planking and framing, plus the added headache of applying fabric, fairing the 'glass then paint.

    This is a bunch more work then just fixing what's wrong and painting her up again, but we all have hills we must climb, in spite of what our cardiologist tells us.
     
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