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  1. #1
    Join Date
    Sep 2019
    Posts
    8

    Default What is "Tar" for a boat owner?

    At present I am going through the process of taking out sample keel bolts from my 1968 GRP yacht which has a cast iron keel. The keel is fixed to the hull with flanges each side of its top edge, so the ends of the bolts are visible from outside. They are easy to knock out once the nuts are removed internally.
    So far I am impressed at the good condition of the sample bolts taken out so far, especially as they have been there years and years, according to the previous owner. I notice that the shanks of the bolts are black as if they were dipped in tar. I remember an old ship repairer in Fraserburgh once telling me that there is nothing like tar for proofing steel against rust. This inclines me to dip the bolts in tar prior to putting them in, whether new replacement or existing.
    But how do I find "tar"? For this purpose does it mean "bitumen"? Do I go up to a gang of Boys from the Black Stuff and ask them for a lump of the black stuff they out put in their pot to melt into gravel? Or is "tar" for boat purposes different stuff? And is "pitch" the same or different again? And where can I get the right stuff?

  2. #2
    Join Date
    May 2001
    Location
    North Wales, sailing Aegean Sea or Menai Strait
    Posts
    22,064

    Default Re: What is "Tar" for a boat owner?

    Tar and bitumen are not the same.

    Tar contains many organic products including aromatics and as such have been banned as being carcinogenic.

    Bitumen is a high molecular weight hydrocarbon that remains after almost everything else has been distilled from crude oil. It would be difficult to use for corrosion protection in this application.

    Pitch is similar to tar and is also likely to be unobtainable.

    Unfortunately you are limited to current commercial products that may offer reduced corrosion protection but are safe for users and manufacturers.
    Answers to some technical queries at new website http://coxeng.co.uk

  3. #3
    Join Date
    Nov 2008
    Posts
    6,993

    Default Re: What is "Tar" for a boat owner?

    Way back in the dim and distant past, we used to heat bolts etc to a "good black" heat (ie not even slightly red hot), and then plunge them into liquid tar. This burned the tar onto the bolts, or other metal fittings, giving them an impermeable skin to prevent corrosion. Possibly that is what has been done with your keel bolts. The "tar" was readily available at any town gas works. I remember going with a 5 gallon drum, and I think they practically gave it away. I'm sure there are better methods nowadays.

  4. #4
    Join Date
    Aug 2013
    Location
    SW Scotland
    Posts
    19,729

    Default Re: What is "Tar" for a boat owner?

    Quote Originally Posted by vyv_cox View Post
    Tar contains many organic products including aromatics and as such have been banned as being carcinogenic.


    "Seamen are always wanting to do things the proper way; and I like to do them my way."

  5. #5
    Join Date
    Mar 2015
    Location
    Isle of Eigg
    Posts
    7,708

    Default Re: What is "Tar" for a boat owner?

    You could make some tar.
    Fill a pressure cooker with nice juicy pine, close the lid and stick it in a (small) fire...

    No, it wont explode since all the oxygen will be expelled before it gets hot enough.

  6. #6
    Join Date
    Jun 2013
    Location
    brightlingsea, essex
    Posts
    100

    Default Re: What is "Tar" for a boat owner?


  7. #7
    Join Date
    Mar 2005
    Location
    East Sussex.
    Posts
    21,505

    Default Re: What is "Tar" for a boat owner?

    Stockholm Tar is tar made from wood, either pine or beech being the main woods used. It is more liquid than the coal tar that used to be available, but there is no reason why it won't do the job of excluding moisture if applied to steel bolts. It is sold for many uses including protecting horses hooves. If buying it I suggest asking how liquid it is and whether it is pure or contains other substances, as you want it as thick and viscous as possible. Telegraph poles used to be protected from rot by Stockholm Tar impregnation and the stuff used on them was very thick at room temperature.
    Working on immortality - One day at a time.

  8. #8
    Join Date
    Jun 2019
    Location
    Shotley
    Posts
    845

    Default Re: What is "Tar" for a boat owner?

    Proper traditional coal tar is definitely still available, it is used for paying seams on historic ships, etc.
    Google caulking irons, seam tar etc, there are a couple of online British suppliers.
    It is totally harmless for your purposes, don't worry about alarmist cancer scares and petty bureaucrats' regulations.
    The same applies to real creosote.
    Although I would also look at Sikaflex and high-tech constuction mastics, there are some amazing products out there.
    "Now shall the gentleman haul and draw with the mariner"
    John Hawkins

  9. #9
    Join Date
    May 2001
    Location
    North Wales, sailing Aegean Sea or Menai Strait
    Posts
    22,064

    Default Re: What is "Tar" for a boat owner?

    Years ago I painted the keel of my first boat with coal tar epoxy, I believe it was an International product. Later I found it had been withdrawn and replaced with a far inferior product with the same name. Several suppliers of coal tar epoxy can be found by Google but the ones I have looked at have also withdrawn the product, e.g. https://www.epoxyproducts.com/coaltar.html Rustoleum say they still make it but not sure if that is current.
    Answers to some technical queries at new website http://coxeng.co.uk

  10. #10
    Join Date
    Aug 2004
    Location
    Home East Lancashire boat Spain
    Posts
    4,730

    Default Re: What is "Tar" for a boat owner?

    Quote Originally Posted by NormanS View Post
    Way back in the dim and distant past, we used to heat bolts etc to a "good black" heat (ie not even slightly red hot), and then plunge them into liquid tar. This burned the tar onto the bolts, or other metal fittings, giving them an impermeable skin to prevent corrosion. Possibly that is what has been done with your keel bolts. The "tar" was readily available at any town gas works. I remember going with a 5 gallon drum, and I think they practically gave it away. I'm sure there are better methods nowadays.
    I seem to recall that many early iron structures were protected in this way ( though I thought it was via burning oil on the metal) Engineers carrying out repairs were surprised that the exposed iron had lasted so well.

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