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Thread: Wooden Boat Fastenings

  1. #1
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    Default Wooden Boat Fastenings

    I have a timber carvel planked 37ft cruiser built in 1937. She has 1" oregon planks on spotted gum frames (1" x 1 3/4", and about 8" apart throughout the length of the boat). Fastenings are clenched copper nails. She takes a little water when underway and I think it will need to be re fastened at least below the waterline. I would like to do this progressively over time, commencing with the next slipping, due shortly. I intend to use silicon bronze screws. Is it necessary to remove the existing copper nails, or can I screw new fastenings in along side the existing ones. The problem I have, apart from time, is that as the boat is in running order, many of the frames are inaccessible from the inside (motor, water and fuel tanks, plus furniture are in the way) making it difficult to get at the clenched part of many of the existing nails. Any advice would be appreciated.

    Pete

  2. #2
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    Default Re: Wooden Boat Fastenings

    A shipwright and wooden boat surveyor friend called driving new fastenings alongside old ones "making sticks with holes". Think the perforations between postage stamps.
    Can you not drill off the copper nails head and punch the nail through to the inside? Then use the old hole as the pilot when you bore for the screw shank and countersink.
    You can find the recommended screw sizes in F S Kinney's,Skeene's
    It really is quite difficult to build an ugly wooden boat.

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  3. #3
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    Default Re: Wooden Boat Fastenings

    When an 80 year old boat needs a tune up, ....
    Re fastening an old girl may not be a thing to do a little bit at a time.
    There are likely caulking issues that are married to the fastenings.
    In other words, she may desire "reefing" the caulking, (relaxing the hull), then the fastening project, then re caulking.
    About halfway through a project like that is when many look at splining the seams, seeking out epoxy alternatives, etc.

  4. #4
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    Default Re: Wooden Boat Fastenings

    The fact that many areas are inaccessible is a bit of a problem. So, screws are the next best way to go in order to fasten from outboard. Herreshoff would call for #12 screws for a boat the size of yours. Since you already have the clinch nails You might consider #10 1 inch flat head bronze. If you think that is too short then go inch and a quarter. It all depends on how deep you plan to bury them. Personally, I would prefer to try to replace the clinch nails with copper rivets wherever possible as they offer the least disturbance to those old frames. Rivets can offer more draw if you are dealing with loose planking.
    Jay

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    Default Re: Wooden Boat Fastenings

    Id follow Nick's advice. Drill or grind off the heads and punch the nails through. Countersink the holes, screw and plug.

  6. #6
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    Default Re: Wooden Boat Fastenings

    Quote Originally Posted by Jay Greer View Post
    The fact that many areas are inaccessible is a bit of a problem. So, screws are the next best way to go in order to fasten from outboard. Herreshoff would call for #12 screws for a boat the size of yours. Since you already have the clinch nails You might consider #10 1 inch flat head bronze. If you think that is too short then go inch and a quarter. It all depends on how deep you plan to bury them. Personally, I would prefer to try to replace the clinch nails with copper rivets wherever possible as they offer the least disturbance to those old frames. Rivets can offer more draw if you are dealing with loose planking.
    Jay
    Just so, "Nail where you can, screw where you must, bolt where you have to" is the old adage.
    It really is quite difficult to build an ugly wooden boat.

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  7. #7
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    Default Re: Wooden Boat Fastenings

    Original 1937 fastenings? I think you are going to find out removing compromised (especially driven ones) fasteners is easier to write about than make happen. 80 yr old copper below the waterline is probably going to crumble or break the first time you start punching.

  8. #8
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    Default Re: Wooden Boat Fastenings

    Quote Originally Posted by BillP View Post
    Original 1937 fastenings? I think you are going to find out removing compromised (especially driven ones) fasteners is easier to write about than make happen. 80 yr old copper below the waterline is probably going to crumble or break the first time you start punching.
    If they were as bad as that she would not
    Quote Originally Posted by PMcKenzie View Post
    takes a little water when underway
    she would be working and leaking like a wicker basket.
    It really is quite difficult to build an ugly wooden boat.

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  9. #9
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    Default Re: Wooden Boat Fastenings

    RE #7
    try a few old fasteners in accessible places, it may give you an indication of the condition of the rest of them and if you do Mess it up they’ll be easier to fix.
    SB and copper are pretty close on galvanic scale so may be worth a try as a “get of jail”. But I like Nicks #2. Also I’d imagine putting more fasteners in they’d be closer together away from edge of planks so benefit may be negligible.
    Last edited by Andrew Donald; 08-20-2019 at 07:25 PM.

  10. #10
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    Default

    I think the question was about the wisdom or otherwise of mixing metals. Someone must have a relevant answer?

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  11. #11
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    Default Re: Wooden Boat Fastenings

    [QUOTE=Peerie Maa;5962724]If they were as bad as that she would not


    she would be working and leaking like a wicker basket.[/QUOT

    Maybe...but not always. I haven't pulled or worked with clenched copper but have refastened bottoms on four of my own sailboats in bronze and galvanized...boats from the 1930s - 50s. They leaked when sailed hard and otherwise mostly stopped at rest. All were at least 50% wasted. The bronze screws were brittle enough to make removal odds 50/50 for replacement. The galvanized (screws and tapered squares) were hourglassed and difficult to pull because they tended to break at the hourglass. None of these leaked like a wicker basket under smooth seas.

    The OP can do his own discovery and find out what does an doesn't work.

  12. #12
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    Default Re: Wooden Boat Fastenings

    Quote Originally Posted by PMcKenzie View Post
    I have a timber carvel planked 37ft cruiser built in 1937. She has 1" oregon planks on spotted gum frames (1" x 1 3/4", and about 8" apart throughout the length of the boat). Fastenings are clenched copper nails. She takes a little water when underway and I think it will need to be re fastened at least below the waterline. I would like to do this progressively over time, commencing with the next slipping, due shortly. I intend to use silicon bronze screws. Is it necessary to remove the existing copper nails, or can I screw new fastenings in along side the existing ones. The problem I have, apart from time, is that as the boat is in running order, many of the frames are inaccessible from the inside (motor, water and fuel tanks, plus furniture are in the way) making it difficult to get at the clenched part of many of the existing nails. Any advice would be appreciated.

    Pete
    Pete, why do you think the fixings are the issue?

    Are you confident that there are not many broken ribs (frames)? Those are very common in this type of construction, at that age. Look for breaks at the tight turn of the bilge, in areas you can access. Also, your caulking, is it in good nick? When you haul her out, try and watch immediately she comes out where water seeps out. Is it coming from the seams, or from around your nails?

    I had a 1954 carvel cruiser, 33', built the same way. The copper nails are clenched, with roves on the inside, same as you have I'd say. The copper is fine. The issues were all in the ribs and caulking (the latter caused by the former, due to movement).

    General tip: If fixings are failing, the timber will be moving, and this will be quite visible (paint split, unevenness in the planks, etc.).

    Your plank hood ends will be screwed to the stem, and those screws are much more likely to have failed than the copper nails, in my view. But as Andrew suggested, you can always try and pull a few in easily accessible places to see what's going on.

    Got any photos?

    There will be plenty of good wooden boat shipwrights around Sydney who will be able to survey your little ship and work out what's really going on. For a few hundreds bucks you'll know.

    Cheers,
    John.
    http://fairmaid.blogspot.com.au/

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  13. #13
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    Default Re: Wooden Boat Fastenings

    Quote Originally Posted by BillP View Post
    Quote Originally Posted by Peerie Maa View Post
    If they were as bad as that she would not


    she would be working and leaking like a wicker basket.
    I haven't pulled or worked with clenched copper
    This is the key statement. I have cared for my fathers 100+ y o boat, copper nailed into alternate steamed frames. The copper nails were the best part of her.
    Weakness due to nail sickness in copper fastened boats is due to the wood fretting around the fastener and enlarging the nail hole.
    John (Aquinian) offers sound diagnostic advice.
    It really is quite difficult to build an ugly wooden boat.

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  14. #14
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    Default Re: Wooden Boat Fastenings

    Quote Originally Posted by Peerie Maa View Post
    This is the key statement. I have cared for my fathers 100+ y o boat, copper nailed into alternate steamed frames. The copper nails were the best part of her.
    Weakness due to nail sickness in copper fastened boats is due to the wood fretting around the fastener and enlarging the nail hole.
    John (Aquinian) offers sound diagnostic advice.
    Here in the states that construction is rare on large boats and most often seen on small skiffs and such...37' carvel with small frames on 8" centers is very uncommon. Anyone with experience refastening a 37'r of that construction is even more uncommon here.

    Sounds like you are saying submerged copper fasteners don't or can't get compromised from electrolysis and have an unlimited life? The only metal I've seen untouched from electrolysis is lead but I've seen copper sheathing compromised from using copper tacks (evidently of a higher purity than the sheets).

    The only certain part of this is new copper fasteners are best used around existing cu fasteners...everything else is 2nd place. I would look for the square cut chisel point copper nails with rings (because I've never seen copper fh screws). Pilot drill and punch into countersink. Use silicone bronze if you can't source copper. I did this with bronze ring nails and it worked fine and was fast (two of us set ring nails next to exist in a 38' Crocker schooner bottom in three long days). Start first around the running gear because that's where most wooden power boats have the worst electrolysis. Stem, transom, garboard, butt blocks...

  15. #15
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    Default Re: Wooden Boat Fastenings

    Quote Originally Posted by BillP View Post
    Here in the states that construction is rare on large boats and most often seen on small skiffs and such...37' carvel with small frames on 8" centers is very uncommon. Anyone with experience refastening a 37'r of that construction is even more uncommon here.

    Sounds like you are saying submerged copper fasteners don't or can't get compromised from electrolysis and have an unlimited life? The only metal I've seen untouched from electrolysis is lead but I've seen copper sheathing compromised from using copper tacks (evidently of a higher purity than the sheets).

    The only certain part of this is new copper fasteners are best used around existing cu fasteners...everything else is 2nd place. I would look for the square cut chisel point copper nails with rings (because I've never seen copper fh screws). Pilot drill and punch into countersink. Use silicone bronze if you can't source copper. I did this with bronze ring nails and it worked fine and was fast (two of us set ring nails next to exist in a 38' Crocker schooner bottom in three long days). Start first around the running gear because that's where most wooden power boats have the worst electrolysis. Stem, transom, garboard, butt blocks...
    Coper nails can corrode, but slowly. I doubt that electrolysis has much to do with it.
    Copper sheathing is sacrificial, it does wear away, so what you describe might not have anything to do with electrolysis.
    Dissimilar methods need not be a problem if the fastenings are sufficiently far apart. Like I said 100-year-old boat, copper into steamed frames alternating with swan frames. The sawn frames and hood ends were nailed with galvo iron. The Iron nails were failing, but no electrolysis was evident anywhere.

    Replacing the nails, where necessary, with silicon bronze screws is a no brainer. As I said above, replace the fastenings, do not drive new alongside the old.
    It really is quite difficult to build an ugly wooden boat.

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