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Thread: Waterproofing , Lineing, Sealing a new centerboard trunk

  1. #1
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    Default Waterproofing , Lineing, Sealing a new centerboard trunk

    I have a 1958 Dunphy Condor and have begun the repairs. The original centerboard trunk was completely rotted out. It originally was lined with fiberglass and was made of plywood sides with pine at both ends. I plan to build a new centerboard trunk of white oak. My question is should I line the new one with fiberglass to to seal it some other way. What is the traditional approach>
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    Default Re: Waterproofing , Lineing, Sealing a new centerboard trunk

    Lining the inside with glass set in epoxy cannot hurt. How will it be bedded down to the keel? Will it be bolted together at the headledges, or glued up into a single unit befor installation?
    It really is quite difficult to build an ugly wooden boat.

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    Default Re: Waterproofing , Lineing, Sealing a new centerboard trunk

    Consider not using oak. Strip planked of a cedar will be very strong , but also dimensional stable and more resistance to rot and borers and friendlier to epoxy.

    Consider not utilizing the metal "L" brackets . That looks like an amateur retro fit.

    Traditional ? Traditionally, they leak, rot and break.

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    Default Re: Waterproofing , Lineing, Sealing a new centerboard trunk

    Thanks for the advice. Good questions. I haven't decided yet. Here are a few of the options I am kicking around:

    1 Build the box and bed it in with epoxy and filler support it in place with the existing structure. That is how it was held in before (except bondo was used)

    2 Remove the existing internal structure around the centerboard and put in a new inner keel section around the centerboard that matches the curve of the bottom of the boat and has a flat top surface to mate with the new centerboard trunk.

    I plan to make the new centerboard trunk with white oak sides and ends dovetailed together at the corners and finished bright.

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    Default Re: Waterproofing , Lineing, Sealing a new centerboard trunk

    oh god , dovetailed cb trunk...better glass the inside.

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    Default Re: Waterproofing , Lineing, Sealing a new centerboard trunk

    Will do.

    I love hand cutting dovetails that's why

  7. #7
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    Default Re: Waterproofing , Lineing, Sealing a new centerboard trunk

    Epoxy and white oak dont get along so well. Solid wood and fiberglass dont get along so well. The trunk sides are going to expand cross grain and split the glass. If you are determined to use white oak, use a good quality oil primer and anyngood exterior oil paint on theninside of the trunk. Finiwh the pieces prior to assembly and then liberally paint the corners after install.

    Dovetailed CB trunk? Thats really gilding the lilly.

  8. #8
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    Default Re: Waterproofing , Lineing, Sealing a new centerboard trunk

    Provide drainage so standing water can't collect.
    Denise, Bristol PA, Oday30, Anchor Yacht Club, On tidal Delaware River. my current project; http://forum.woodenboat.com/showthre...0-Ducker-Resto

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    Default Re: Waterproofing , Lineing, Sealing a new centerboard trunk

    That's my plan for the areas I repair. I will put limber holes in the sole supports as I put them back in. For the remaining ones as I get to them I will keep a sponge aboard.

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    Default Re: Waterproofing , Lineing, Sealing a new centerboard trunk

    Quote Originally Posted by kleppermaster View Post
    Thanks for the advice. Good questions. I haven't decided yet. Here are a few of the options I am kicking around:

    1 Build the box and bed it in with epoxy and filler support it in place with the existing structure. That is how it was held in before (except bondo was used)

    2 Remove the existing internal structure around the centerboard and put in a new inner keel section around the centerboard that matches the curve of the bottom of the boat and has a flat top surface to mate with the new centerboard trunk.

    I plan to make the new centerboard trunk with white oak sides and ends dovetailed together at the corners and finished bright.
    Shape the bedlogs to fit the existing curve of the inner keel or hogg, assuming that it is sound and can be retained.
    You cannot dovetail. The end pieces called headledges are timbers with their grain running along their length that are sandwiched by the sides and bed logs, and often extend through the keel for strength and stability. No way you can cut dovetails in them, the grain runs in the wrong direction.
    It really is quite difficult to build an ugly wooden boat.

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    Default Re: Waterproofing , Lineing, Sealing a new centerboard trunk

    I'll think about this. The original did not extend through the keel. Also, I'm a bit puzzled about the grain direction statement. If I make the ends vertical grain and the sides horizontal grained the expansion and contraction will fight. If I dovetail all the wood grain will be horizontal and will expand and contract together.

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    I've often thought about making the cheeks of a centerboard or daggerboard trunk removable.

    The actual stress is that the top and bottom openings. it would certainly make maintenance a lot easier.
    Denise, Bristol PA, Oday30, Anchor Yacht Club, On tidal Delaware River. my current project; http://forum.woodenboat.com/showthre...0-Ducker-Resto

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    Default Re: Waterproofing , Lineing, Sealing a new centerboard trunk

    Quote Originally Posted by kleppermaster View Post
    I'll think about this. The original did not extend through the keel. Also, I'm a bit puzzled about the grain direction statement. If I make the ends vertical grain and the sides horizontal grained the expansion and contraction will fight. If I dovetail all the wood grain will be horizontal and will expand and contract together.
    Back in the day when cb cases were made out of several boards the headledges kept the joints tight. They also resist the stresses trying to push the CB case over. Your cross grained headledges will split and break up. Do not try to reinvent the wheel. Headledges are the way they are for a reason.



    It really is quite difficult to build an ugly wooden boat.

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    Default Re: Waterproofing , Lineing, Sealing a new centerboard trunk

    OK I see why yours goes through the keel and mine does not. Yours is a much lighter non blasted craft. Mine is a Lead Sled with a lot more keel, deadwood and external lead ballast below the cockpit sole. Most of my centerboard is in the keel and only half or less comes up into the cockpit. The CB pivot rest right on the inner keel. The CB trunk is there only for looks and keeping water out. The CB does not bear against it. All forces are reacted against the keel. The centerboard trunk is about 4-1/2 inches wide and only about 10 inches tall. Over half of the trunk is supported from the sides by the ribs that butt up against it. Since my centerboard trunk is so wide and short & no CB forces are reacted against it, it does not need the extra support of the head ledges passing through the keel. I am not reinventing the wheel I have used this approach successfully on other projects. I plan to go ahead with it and if it fails I will repent.

  15. #15
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    Default

    headledges....🙃

    "either of the upright end posts of a centerboard box'
    Denise, Bristol PA, Oday30, Anchor Yacht Club, On tidal Delaware River. my current project; http://forum.woodenboat.com/showthre...0-Ducker-Resto

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    Default Re: Waterproofing , Lineing, Sealing a new centerboard trunk

    Having recently read half a dozen horror stories of wedged up centerboards. I am making a mental note that I should construct my next one with surfaces as hard and smooth/slick as possible, so that there's no give in the surface to let a wider than gap pebble in, and hopefully it will be low friction enough that anything that gets in there still lets you move the board. Hopefully ejecting it if you work it up and down. So oak = hard = good from that perspective, but since it is picky about what it lets stick to it, you've got assembly and protection issues. Cedar being on the soft side I would prefer to have a hard coating so epoxy works there.
    2019: returning from being sidelined with medical probs, crossing fingers worst is over, still in "armchair enthusiast" mode for time being.

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    Default Re: Waterproofing , Lineing, Sealing a new centerboard trunk

    Quote Originally Posted by kleppermaster View Post
    OK I see why yours goes through the keel and mine does not. Yours is a much lighter non blasted craft. Mine is a Lead Sled with a lot more keel, deadwood and external lead ballast below the cockpit sole. Most of my centerboard is in the keel and only half or less comes up into the cockpit. The CB pivot rest right on the inner keel. The CB trunk is there only for looks and keeping water out. The CB does not bear against it. All forces are reacted against the keel. The centerboard trunk is about 4-1/2 inches wide and only about 10 inches tall. Over half of the trunk is supported from the sides by the ribs that butt up against it. Since my centerboard trunk is so wide and short & no CB forces are reacted against it, it does not need the extra support of the head ledges passing through the keel. I am not reinventing the wheel I have used this approach successfully on other projects. I plan to go ahead with it and if it fails I will repent.
    What does the designer specify for that boat? He is the expert in such matters.
    It really is quite difficult to build an ugly wooden boat.

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    Default Re: Waterproofing , Lineing, Sealing a new centerboard trunk

    The juxtaposition of dovetails and one face surface only encapsulated wood is like good fighting evil. There will be a tussle like few boats have seen. Don't worry about if it will fail. Start planning now on what to do to replace it (again).

    Jeff

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    Default Re: Waterproofing , Lineing, Sealing a new centerboard trunk

    If it is there for "looks only and keeping water out ",....

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    Default Re: Waterproofing , Lineing, Sealing a new centerboard trunk

    If the original plywood part lasted sixty years,why not just repeat and give the inside a few coats of epoxy?Using solid oak and cutting lots of dovetails will take longer and very likely leak.

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    Default Re: Waterproofing , Lineing, Sealing a new centerboard trunk

    The case on my gp14 is solid mahogany, it is slightly warped from 55 years of use and storage. I took it apart this winter as it was leaking from dried out sealer. The inside of the case was coated in some firm of oil/creosote. I left good enough alone, resealed it, screwed back together with new bronze screws, and stripped and varnished the outside as ped original. It will hopefully go back into the boat next week
    "If you think you are too small to make a difference, try sleeping with a mosquito"

    -Dalai Lama

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    Default Re: Waterproofing , Lineing, Sealing a new centerboard trunk

    Quote Originally Posted by John Meachen View Post
    If the original plywood part lasted sixty years,why not just repeat and give the inside a few coats of epoxy?Using solid oak and cutting lots of dovetails will take longer and very likely leak.
    John,

    You don't have much respect for my fine woodworking ability. I'm offended! LOL

    Also, I have lots of nice white oak and no marine plywood on hand. Plus, I am retired with more time than money.

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    Default Re: Waterproofing , Lineing, Sealing a new centerboard trunk

    Quote Originally Posted by Peerie Maa View Post
    What does the designer specify for that boat? He is the expert in such matters.
    The Naval Architect (A.M. Deering) is long dead and I have never seen or heard of a set of plans for this craft. If you have any idea where I can get them, I be deeply appreciative.

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    Default Re: Waterproofing , Lineing, Sealing a new centerboard trunk

    Quote Originally Posted by kleppermaster View Post
    The Naval Architect (A.M. Deering) is long dead and I have never seen or heard of a set of plans for this craft. If you have any idea where I can get them, I be deeply appreciative.
    I already suggested how it should have been built, but you do not seem to be interested in this Naval Architects advice, so I suggested a higher authority. Being British I have never heard of A M Deering or his designs, so you will have to do your own digging.
    It really is quite difficult to build an ugly wooden boat.

    The power of the web: Anyone can post anything on the web
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  25. #25
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    Default Re: Waterproofing , Lineing, Sealing a new centerboard trunk

    Quote Originally Posted by Peerie Maa View Post
    I already suggested how it should have been built, but you do not seem to be interested in this Naval Architects advice, so I suggested a higher authority. Being British I have never heard of A M Deering or his designs, so you will have to do your own digging.
    So are you from Great Britton? I am from the Imagi-Nation just outside of the British isles. Actually I'm a mutt descended from (here is the known list):
    England
    Ireland
    Scotland,
    France

    Probable list:
    Germany (from the Saxon invasion)
    Italian (from the Roman invasion)
    Danish (from the Viking invasion)

    And quite certain I'm a direct descendant from Lucy (from the Rift Valley of Africa).

    Just working on my stand-up. No I don't plan to give up the day job.... Oh wait, I'm retired!

    A.M. Deering was a respected Navel Architect that lived and worked in Chicago.

    He designed the Condor for the Dunphy Boat Co. who built my Condor

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