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Thread: Painting Bobstay Chain

  1. #1
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    Default Painting Bobstay Chain

    Wandering Star has galvanized chain bobstays, they rust at the lower end, where they are continuously splashed with seawater. I trim the rusty links, four years ago (I think) I painted one with zinc paint, which helped protect it. I am going to paint both this time, I can use the zinc, or something else. I have considered roof tar, which should protect really well, but might also conceal rust. Has anyone painted bobstay chain? What did you use?

  2. #2
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    Default Re: Painting Bobstay Chain

    I buy galvanized paint by the Qt. can, about $50 (it's heavy!) https://www.mcmaster.com/#galvanizing-paint/=1cmikbt


    or; http://www.suncorstainless.com/chain

  3. #3
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    Default Re: Painting Bobstay Chain

    I switched away from a chain bobstay on Goblin when I observed how it's not just rust but splash induced electrolysis (that also eats copper based anti-fouling paints at the waterline) and then began reading about how chain distorts underload and how hard it is to inspect prior to sudden catastrophic failure. Proper 1x19 stainless cable is the way to go.

    Any bobstay, chain or cable, can be hard on an anchor rode, especially if your boat tacks on the mooring or anchor. This problem is easily fixed by having a snatch block or a clear plastic hose covered loop on the end of a line hung from a cheekblock just aft of the cranse iron and running back to some place you can belay to. Have it stored with both ends stowed conveniently alonside the bowsprit on deck. Once the anchor is set or the mooring picked up, put the loop or block on the rode and let it pendulum slide down. Trim until it had drawn the rode snugly up under the bowsprit end.

    To retrieve, let it off till it can hang loosly and bring the anchor up. The thing will slide along down the rode till it come home with the anchor, where it's easily detached.

  4. #4
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    Default Re: Painting Bobstay Chain

    Thank you both. I prefer the chain for several reasons: chafe, ease of making and installing, the ability to climb it from the water if necessary.
    I'm also looking at stainless chain.

  5. #5
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    Default Re: Painting Bobstay Chain

    I switched to high resistance stainless chain this season, fed up with treating and repainting every year.
    They agreed to sell me only 4 meters long.
    These chains are intended for mooring and rather expensive , but for a bobstay you need short lengh.
    http://www.toplicht.de/en/shop/anker...elektropoliert
    Last edited by Rapelapente; 04-29-2018 at 01:01 PM.
    Gerard.
    SCHOONER FOR EVER, GOELETTE A PERPETE

    http://www.schooner-anthea.com

  6. #6
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    Default Re: Painting Bobstay Chain

    Go at the chain by hand with a wire brush, then lay on the zinc paint quite thickly. Make sure both are warm.

    The coating lasts for 5 years or more on Drake, in fresh water.

    Or, buy hot-dipped galvanized chain and start afresh.

  7. #7
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    Default Re: Painting Bobstay Chain

    I use chain for whiskers to step on , but wire for the bobstay. I double em up . Chain ain’t really all that strong.

  8. #8
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    Default Re: Painting Bobstay Chain

    I'm using 3/8" chain, plenty strong, it's worked well for fifty years on this boat. I did think of buying stainless, but then remembered that there was some more new chain in the chain locker. I broke that out and washed it off. I'll paint it with Rustlok when it dries. Maybe in ten years I'll look at stainless again. Thank you all.

  9. #9
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    Default Re: Painting Bobstay Chain

    You may be fine with it, but I'll bet that you have at least a 3/8" head stay which has a minimal breaking strength of 17,500#. In rigging, 'safe working load' is taken as half that. So, compare that SWL of 8,750# with 3/8" proof or BBB at 2,650# or 3/8" high test at 5,400#.

    As a note, the reason cable is usually rated at breaking strength while chain at safe working load is that chain's actual breaking strength is more erratic and depends on whether it's been subjected to near breaking.

    In principle the bobstay takes considerably more loading than the jib stay. In reality, many old bow sprit boats are so loose that things sag off, unloading the rig, and everything stays within a safety zone. Until it breaks. Having broken seven masts, maybe I just consider this more than most.

  10. #10
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    Default Re: Painting Bobstay Chain

    When I converted my bowsprit to a "reefing" unit, I just tossed the galvanized chain bob-stay and replaced with a 4-part tackle using some fiddleblocks I made from some walnut. This also allowed me to "tune" the jibstay tension. I already had a fixed forestay at the stem fitting, so the bowsprit and bob-stay were in place just for the jib and there was no risk of loosing the mast if it failed.

    Last edited by BrianM; 05-01-2018 at 02:44 PM.

  11. #11
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    Default Re: Painting Bobstay Chain

    If you have a forestay to the stem, then the rig is pretty safe and in fact that stay may be taking enough of the load that one can get away with a weak chain bobstay. Goblin's bowsprit was ripped of by an evil power boat. It was a calm night and we were before the wind, so there was that, but really we were at no risk of losing the rig. Lost my temper but the rig was safe.

  12. #12
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    Default Re: Painting Bobstay Chain

    She hasn't spent 50 years at the dock. The chain has proven itself, she still has her masts in her. The forestay goes to the sprit too.

  13. #13
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    Default Re: Painting Bobstay Chain

    Quote Originally Posted by Rapelapente View Post
    I switched to high resistance stainless chain this season, fed up with treating and repainting every year.
    They agreed to sell me only 4 meters long.
    These chains are intended for mooring and rather expensive , but for a bobstay you need short lengh.
    http://www.toplicht.de/en/shop/anker...elektropoliert
    FWIW, that chain is made of 1.4462 (2205) duplex stainless. Much better than 316 in terms of strength and corrosion.
    The higher the PRE, the better the pitting corrosion resistance.
    Duplex 2205 has a PRE average value of 38, being in theory more resistant than 316, with an average value of 25.

    3/8 is just under 10mm. The safe working load is listed as 52kN (11690 lbf), which seems a bit too high, roughly equivalent to 7/16" (11.1mm) Gr 100
    <<EDIT: By that I meant the SWL was plausible, but I wanted a second opinion (US Stainless 22480 break -->11240 SWL) before I bet my life on it. $26/ft on Amazon says that it is more than twice as strong as 316, but which 316?.

    http://www.cromox.eu/pdf/en/UG-Nautic-Anchor-Chains-en.pdf
    >>

    Steel Chain grades
    Last edited by MN Dave; 05-01-2018 at 12:39 PM.
    Management is the art of counting beans. Leadership is the art of making every being count. --Joe Finch

  14. #14
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    Default Re: Painting Bobstay Chain

    The previous one was 12 mm galvanised.
    I bought the 13 mm. So I'm pretty confident with The 88.5 kN working load and 177 kN breaking load.
    Gerard.
    SCHOONER FOR EVER, GOELETTE A PERPETE

    http://www.schooner-anthea.com

  15. #15
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    Default Re: Painting Bobstay Chain

    Quote Originally Posted by Ian McColgin View Post
    I switched away from a chain bobstay on Goblin when I observed how it's not just rust but splash induced electrolysis (that also eats copper based anti-fouling paints at the waterline) and then began reading about how chain distorts underload and how hard it is to inspect prior to sudden catastrophic failure. Proper 1x19 stainless cable is the way to go.

    Any bobstay, chain or cable, can be hard on an anchor rode, especially if your boat tacks on the mooring or anchor. This problem is easily fixed by having a snatch block or a clear plastic hose covered loop on the end of a line hung from a cheekblock just aft of the cranse iron and running back to some place you can belay to. Have it stored with both ends stowed conveniently alonside the bowsprit on deck. Once the anchor is set or the mooring picked up, put the loop or block on the rode and let it pendulum slide down. Trim until it had drawn the rode snugly up under the bowsprit end.

    To retrieve, let it off till it can hang loosly and bring the anchor up. The thing will slide along down the rode till it come home with the anchor, where it's easily detached.
    Ian, you brought up a consideration that I had not thought of. I was thinking of using copper based bottom paint on my sharpie. Would the sharpie with copper based bottom paint lose that paint at the water line at the marina and/or from splash while sailing? If so, what are the alternatives? I will not be racing.

  16. #16
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    Default Re: Painting Bobstay Chain

    The copper paint on WS does not seem to suffer from the proximity of the galvanized chain. The chain rusts heavily at the waterline, maybe accelerated by the copper. The fitting on the stem is stainless steel and probably original. I last cut rusty links off four years ago, the boat is usually in the water year round.

  17. #17
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    Default Re: Painting Bobstay Chain

    The splash induced electrolysis I mentioned applies sepearatly to a bobstay (much dependent on the material and structure) and bottom paint.

    Take a piece of copper with a wire from one end to a sensitive ampmeter and thence to the other end. Hold the bit of copper vertical in a suitable electrolite like salt water and move it up and down. You'll get a current.

    This is what happens to copper based bottom paint just above and below the waterline. Just give it an extra coat. Or use one of the modern non-copper eco-sensitive bottom paints.

    With bobstays, stainless is resistant to splash induced electrolysis but stainless chain has other problems that make it unsuitable for a bobstay. With steel chain, proof or high test, the problems of rust are compounded by mild electrolysis because chain has so many exchange sites where trouble can begin. Like everywhere link wears on link.

    Besides the fact that ss cable for a given size is stronger and lighter than chain (ever notice that no one makes chain shrouds?) there is inspectability. It's very hard to look at a bit of chain and see danger. Cable is generally a give-away especially near terminals. Of my seven broken masts, none were due to the cable failure. All were associated solid fittings. Or in three cases, my own radical stupidity.

  18. #18
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    Default Re: Painting Bobstay Chain

    Quote Originally Posted by Ian McColgin View Post
    ......(ever notice that no one makes chain shrouds?) .....
    Certainly according to the weight.
    So why the chainplates are so called? The translation in french, "cadene" comes from the Latin cadena meaning chain.
    I understand your arguments about the better resistance of wires. My concern is precisely the lower wire fitting corrosion, constantly soaked with sea water, hidden inside.
    And since I have a full chain mooring , chafing chain on wire is also a problem. Even if only on short term, because for overnight mooring, I set a hooked line to avoid it.
    Anyways, on Anthea's new stainless chain bobstay, the weakest links remain the upper turnbuckle and the lower fast link.
    IMG_9555 copie.jpg
    Last edited by Rapelapente; 05-03-2018 at 02:43 AM.
    Gerard.
    SCHOONER FOR EVER, GOELETTE A PERPETE

    http://www.schooner-anthea.com

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