yet more rotten wood.

Discussion in 'Wooden Boat Building and Restoration' started by Alecdp, Aug 3, 2011.

  1. Alecdp
    Joined: Aug 2011
    Posts: 1
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    Location: Chile

    Alecdp New Member

    Hello all, this is my first post I found this forum after searching for more information concerning my problem and thought this would be the place to ask.

    Well this will be a long story.

    I am chilean, (long & thin country at the southern tip of south America so please excuse me if my english is not perfect) around 1999 my father decided it would be a great idea to have a small family boat so that we could spend summers all together. He decided that this boat would be made by Chiloé (the biggest south American island) artisans following their traditional methods, so he found a few artisans and got down to it. To get the blueprints he went to a local boatmaking legend, but instead of getting blueprints the end result was a half model of the future boat. This was measured and the model expanded.

    http://www.boatdesign.net/forums/attachment.php?attachmentid=59403&stc=1&d=1312414083

    http://www.boatdesign.net/forums/attachment.php?attachmentid=59402&stc=1&d=1312414083

    A big tree was used for the keel (yes only one), then the ribs or frames were secured, the keelson was fastened, the hull was completed and then we realized that the results were bigger than what we had imagined.
    http://www.boatdesign.net/forums/attachment.php?attachmentid=59404&stc=1&d=1312414083
    Ok, now here is when the problem starts... Winter is ending, the sun is coming out and temperatures are starting to rise, the trees used have recently been cut down so they are still a bit green and the timber is starting to dry too fast and therefore starting to crack something of course really undesirable.

    http://www.boatdesign.net/forums/attachment.php?attachmentid=59405&stc=1&d=1312414083

    So a big Hangar was built around the boat, this was made mostly because there was a fleet of wooden fishing boats that needed it so that some revenue could be obtained later by this building and the whole boat was painted with a white or gray pol paint so that the wood would be protected from the sun while the hangar was finished.

    The construction extended for over 3 years. Until finally the boat sailed and it was perfect... Until 2 years ago.


    2008 (6 years after the launch) we noticed a soft spot in the stem, upon investigation the rot was extensive enough to have to replace the stem, the rot had also extended to some of the forward frames, these were also replaced.

    Last year the sternpost revealed some softspots, upon inspection the rot was extensive enough to have to replace it and with it most of the lower parts of the frames.

    Regrettably I cannot completely inspect the frames in the midsection of the boat as the access is limited because they are below the cabins bathrooms, but already there is evidence of rot in the places I've inspected although the rot does not seem to be that extensive.

    Last time I went to survey the damage and the replacement of the damaged wood I did not take my camera so I don't have any pictures but I will go back in a couple of weeks where I will be able to get them.

    The big question is why would this happen, after talking with a few knowledgable people they have told me that it could have been because the timbers were green when they where painted so there was some moisture trapped inside or that the wood did not have enough ventilation to maintain the frames dry.

    Suggestions of what to do concerning the partially rotted frames still in place are helpful and thanked.


    Hope you have the time to read and knowledge to help.

    cheers
     

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  2. Bob Smalser
    Joined: Jun 2003
    Posts: 79
    Likes: 11, Points: 0, Legacy Rep: 159
    Location: Seabeck, WA

    Bob Smalser Junior Member

    http://forum.woodenboat.com/showthr...d-other-Wood-Pestilence.&highlight=pestilence

    Why?

    Green lumber used in building has to be seasoned either during the build or in service to below 20% moisture content or it will rot where it also gets oxygen. And no amount of lead, copper or borate rot preventatives will prevent it. If your framing was of a typical boatbuilding hardwood, it was at around 60% moisture content when installed, and between painting it, adding more green lumber atop it, closing it in with a deck and launching it, it never had a chance to reach the below-20% threshold required for longevity.

    The only course of action is to beach the boat, ventilate it thoroughly, and replace the rotted components using properly-seasoned wood.
     
    1 person likes this.
  3. BATAAN
    Joined: Apr 2010
    Posts: 1,614
    Likes: 99, Points: 0, Legacy Rep: 1151
    Location: USA

    BATAAN Senior Member

    Of course traditional boatbuilding of work boats has usually been of green or little-seasoned wood (Gloucester schooners as an example), the idea being to launch the boat immediately in salt water and let things sort themselves out while you are making money. The 'design life' of these vessels was about 12 years, then they were soft enough everywhere as to be uneconomical to repair, so were replaced.
    Yacht building, on the other hand, is not concerned with immediate profit, but making the best vessel possible with a very long life.
    This means seasoned and properly dried lumber of the best quality, faying (painting) of all mating surfaces, and in the best builds like ELBE 5 (schooner WANDERBIRD) built in 1882 in Germany, felt and tar between every piece of wood and under every piece of metal. This makes it so if one piece rots, it does not spread. When I built BERTIE I used red lead and roofing felt over the frame heads and all the deck beams after seeing this lesson on the
    Most local work boat artisans are not trained in these methods as their market will not tolerate extra costs. They build excellent, strong boats, but without the long design life in mind.
    I was Capt of NINA, a replica of Columbus ship built in Brazil in 1991, which was entirely constructed using 15th century methods; no model, no drawings, green wood and all and she is still around but has constant problems with her structure from this approach. Her sheer strakes are one piece, no butts, 70' long 4x14 inch hardwood that was worked green because it's the only possible way to do that job.
    Your vessel looks like a capable and efficient design and is possibly able to be saved.
    I agree with the poster above that you should haul the boat, pull some bottom planks so you can see what is going on, and replace every rotten piece of wood as far as possible.
    To keep the boat drier inside, largeventilators and lots of them should be installed, especially in the ends. These should have screens in them of a size to keep out termites and flying ants that eat wood.
    The deck must be perfectly tight, with no rain water leaks in dark corners.
     

  4. broncobilly60
    Joined: Jan 2012
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    Location: san jose ca.

    broncobilly60 Junior Member

    Fungus is a like a plant. In ideal conditions it grows just like a plant. It also breakes down the cells that hold the wood together. Once dryrot sets in it cannot be treated but must be removed and new wood installed. All wood is can rot but there are several products on the market that can be used to coat the wood to prevent the growth of fungus/dryrot. Dryrot occurs when wood is wet and then is given a chance to dryout and attain ideal temperature and moisture content to allow for growth. Boron is a great non toxic wood preservative. It disolves in water and can be brushed or sprayed on the surface of the wood and then allowed to dry. Timbor made by BASF is such a product.
     
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