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Thread: Steel plate ballast, fasteners.

  1. #1
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    Default Steel plate ballast, fasteners.

    Hi,

    I hope for some help from you.

    I am building William D. Jochems, a Phil Bolger design. The boat is a kind of sharpie with a flat bottom. I have decided to go for steel plate ballast, this is the designer’s recommendation as an alternative to ballast tanks.
    I am just about to order the steel plates, 15 plates, 720 Kg, they will cover almost the whole bottom. The plates will be 10 mm thick and hot dipped galvanized. The design specifies that they are fastened with 3/8” countersunk bolts. There are 72 pcs. of these. I intend to use mild steel hot dipped galvanized bolts, washers an nuts.

    I found a company in England who has got these bolts and was willing to send these to me in Norway. However, the last I heard from them was that they had to have some kind of form stamped by the chamber of commerce to satisfy our customs authorities. This would make the total cost for paperwork and freight about £ 150 - 170. This is rather expensive in addition to the fasteners themselves. There is also a 25% Norwegian VAT On the whole amount.

    I am thinking about a couple of alternatives for fasteners I can get more locally.

    1. Use stainless steel, preferably 316L, but I would like to avoid mixing materials below the waterline.

    2. Use electroplated mild steel fasteners, spray the heads with zinc rich paint after installation and hope that the galvanized steel plates protect the bolts.

    What is your opinion on this?

    I think this kind of ballast has been used before. What’s your experience?

    - Oddbjorn

  2. #2
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    Default Re: Steel plate ballast, fasteners.

    I am assuming that you are getting the plates hot dipped locally, yes?
    So have them dip the bolts nuts and washers as well, then buy a die nut and tap to clean up the threads.
    Can you get hot dipped coach bolts? I think that M8 is the equivalent to 3/8''. A shallow counter bore will sink the heads for stopping over.
    If that is not possible, dip the bolts in zinc rich as you install them, then paint again with a second coat.
    It really is quite difficult to build an ugly wooden boat.

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  3. #3
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    Default Re: Steel plate ballast, fasteners.

    Don't use stainless steel – electrolytic action will destroy the galvanizing on the ballast plate.

    Bright zinc plated is pretty useless but at least won't mess with the ballast galvanizing.

    If you can buy the (un-galvanized) bolts locally, run a slightly over-tightened die (not a die nut) down the threads and then send them for galvanizing with the ballast. Ask for them to be spun, which should give a good finish.

    Cheers -- George
    To be truly free to live, one must be free to think and speak.

    A C Grayling

  4. #4
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    Default Re: Steel plate ballast, fasteners.

    Thank you.

    Quote Originally Posted by Peerie Maa View Post
    I am assuming that you are getting the plates hot dipped locally, yes?
    So have them dip the bolts nuts and washers as well, then buy a die nut and tap to clean up the threads.

    - Yes, that’s a possibility. It is possible to buy hot dipped washers and nuts here , so It is only the bolts that must be treated. I will look into this.

    Can you get hot dipped coach bolts? I think that M8 is the equivalent to 3/8''. A shallow counter bore will sink the heads for stopping over.

    - 3/8” is more like M10, but that does not matter. I am having the steel plates produced by a “machine shop(?)“ and I fear that special countersinks will make them more expensive.

    If that is not possible, dip the bolts in zinc rich as you install them, then paint again with a second coat.
    - Oddbjorn

  5. #5
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    Default Re: Steel plate ballast, fasteners.

    Thank you,

    Then I got some support for avoiding stainless bolts.

    - oddbjorn

  6. #6
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    Default Re: Steel plate ballast, fasteners.

    Have you got the holes drilled in the plate steel yet?

    Just a thought; use 8mm threaded bar, 316 SS, set sections of it into the keel with epoxy (aka chemical anchor).
    Sheath the threaded bar with hose (so your steel plate will need holes big enough for the hose). Drop the plates onto the rod, cut off any hose poking up and then clamp down with locknut - possibly plastic/rubber washer between SS and gal.

    Counter sunk heads may imply little room - in which case there may not be space for the head of the rod and a nut.

    I wouldn't go imperial if i were you. Use a metric equivalent and you can source the parts in Norway more easily.
    It's all fun and games until Darth Vader comes.

  7. #7
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    Default Re: Steel plate ballast, fasteners.

    The steel plates will be installed outside on the bottom to provide protection when the boat sits on the bottom intentionally or in case of grounding. I therefore want to use countersink bolts from outside to avoid bolt heads or nuts protruding below the plates. There will be nuts inside the bottom. This is a plywood boat. The bottom is 24 mm thick and there is a central shoe with a total thickness of 60 mm.

    - oddbjorn

  8. #8
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    Default Re: Steel plate ballast, fasteners.

    What about using the 8mm threaded bar, mild steel, tapped into the plates prior to galvanizing? Perhaps pein the outer ends or have them tack welded to prevent spinning when you put the nuts on inside?

  9. #9
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    Default Re: Steel plate ballast, fasteners.

    Quote Originally Posted by Hugh MacD View Post
    What about using the 8mm threaded bar, mild steel, tapped into the plates prior to galvanizing? Perhaps pein the outer ends or have them tack welded to prevent spinning when you put the nuts on inside?
    Really difficult to do that if there is any rocker on the bottom.

    Hot galvanized M10 (or ⅜") countersunk bolts really do seem the best option – preferably with a plain shank and only a short length of thread, though these may not be available in short lengths.

    You could try for hot galvanized countersunk head machine screws – it's better if there is no thread all the way, but it's not that bad!

    Cheers -- George
    To be truly free to live, one must be free to think and speak.

    A C Grayling

  10. #10
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    Default Re: Steel plate ballast, fasteners.

    I would save a whole lot of headaches and expense by fitting the steel between the floor timbers on the inside where they can be held in place with cleats to the sides of the timbers and chines. I'm doing that with lead on my big dory build. Is there a good reason for you not to do that?

    You can then protect the bottom with glass or xynol in epoxy instead of the steel, and the ballast can be easily removed whenever necessary.
    Last edited by Gib Etheridge; 07-22-2020 at 11:36 AM.

  11. #11
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    Default Re: Steel plate ballast, fasteners.

    Quote Originally Posted by Gib Etheridge View Post
    I would save a whole lot of headaches and expense by fitting the steel between the floor timbers on the inside where they can be held in place with cleats to the sides of the timbers and chines. I'm doing that with lead on my big dory build. Is there a good reason not to do that?

    You can then protect the bottom with glass or xynol in epoxy instead of the steel, and the ballast can be easily removed whenever necessary.
    Yep that seems a lot more sensible to me. If it's fitted externally, the galvanizing is just going to get worn off anyway after a few groundings.

    George
    To be truly free to live, one must be free to think and speak.

    A C Grayling

  12. #12
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    Default Re: Steel plate ballast, fasteners.

    ^ yeah me three. Way simpler.
    And you can move it around for trim.
    It's all fun and games until Darth Vader comes.

  13. #13
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    Default Re: Steel plate ballast, fasteners.

    I see fisherman round my way use old car steel brake discs for ballast on the fishing gear sometimes. Just a thought...you could derust then paint them with international VC TAR2 if you wanted them smart. Treat it like an iron keel with the prep. Its easy to use that VC TAR 2 stuff. Disc come with holes in...could dyneema be used to hold them down if your doing things differently?
    Last edited by Edward Pearson; 07-22-2020 at 04:51 AM.

  14. #14
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    Default Re: Steel plate ballast, fasteners.

    I am probably too hung up in following the designer’s suggestions. I have made patterns for the fifteen steel plates and have all but given the shop the go ahead. I think it’s good to have the protection from the steel plates. The plates will be rolled to follow the curve of the bottom.

    - oddbjorn

  15. #15
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    Default Re: Steel plate ballast, fasteners.

    Key word = "TOO". It pays to be flexible.

  16. #16
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    Default Re: Steel plate ballast, fasteners.

    Perhaps you can have them punch square holes for the bolts and use carriage bolts rather than counterbores that have to be filled.

  17. #17
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    Default Re: Steel plate ballast, fasteners.

    Will the rather flat but still protruding heads of the carriage bolts add a lot to the resistance in the water? It’s 72 bolts.

  18. #18
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    Default Re: Steel plate ballast, fasteners.

    Quote Originally Posted by Oddbjorn View Post
    Will the rather flat but still protruding heads of the carriage bolts add a lot to the resistance in the water? It’s 72 bolts.
    You need to read Jim Michalaks story about rocket scientists arguing how the rivet heads protruding on the surface would slow the rocket down so much it would probably fail to reach its trajectory, only to discover in practice, that it went faster and further.......something about the heads breaking up the "boundry layer", and i suppose induced more air and less friction. I would not worry about dome head on carriage bolts being exposed.

  19. #19
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    Default Re: Steel plate ballast, fasteners.

    I too would also consider putting the plate inside. I had the same issue to consider with my stel re-bar and concrete shoe ballast casting. My last thought was to glass the entire bottom. Easier to look after a glass bottom in way of repair and paint, than to deal with rusty steel. If you are considering drying out on rocks, just remember that steel plate is only on the bottom, your ply sides are just as vunerable to accidents.

  20. #20
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    Default Re: Steel plate ballast, fasteners.

    Carriage bolts are certainly an option. The old steel ships had riveted plates, and they did move. I have however noticed, when entering an aircraft that the rivets are countersunk.

    As for inside ballast I would rather follow Phil Bolger’s (the designer’s) recommendations. The outside steel plates are flush with the corner between the side and the bottom and I think they offer some protection.

    There have been built some boats with such plates it would be interesting to hear from those builders or owners.

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