How are structural poles like this normally secured?

Discussion in 'Boatbuilding' started by snowbirder, Jul 6, 2015.

  1. snowbirder

    snowbirder Previous Member

  2. PAR
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    PAR Yacht Designer/Builder

    Flanged and through bolted, though bigass screws are used sometimes.
     
  3. Petros
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    Petros Senior Member

    you will want a sturdy positive attachment, it is unsafe the way it is, a strong gust could lift it and than it could rip off or come down on your head.

    something like this, use sealant and corrosion resistant hardware (stainless). keep moisture out of all contact surfaces with sealant. Also, it should use a through bolt, not the set screw as shown (this was just an example image I found on the internet).

    [​IMG]
     
  4. Charlyipad
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    Charlyipad Senior Member

  5. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    This is a threaded flange, but welded is also common.

    [​IMG]
     
  6. snowbirder

    snowbirder Previous Member

    Thanks for the replies.

    I had been searching for the aluminium flanges (my tubing is aluminium), but can only seem to find small, handrail size.

    My tubing is 4" diameter.

    Anyone know where to source these? Google didn't help me.
     
  7. FMS
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    FMS Senior Member

    Stub Ends - Short Type

    Stainless Steels: Types 304, 304L, 304H, 316, 316L, 316H
    Inco Alloys: Monel 400, Nickel 200
    Aluminum Alloys: Types 3003-F, 6061-T6
    Other Alloys: Inquire
     
  8. PAR
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    PAR Yacht Designer/Builder

    It's also not especially difficult to weld up some flanges, from commonly available stock. It's usually cheaper this way, if you need a few.
     
  9. snowbirder

    snowbirder Previous Member


    That's some great Google-fu! thanks!

    I'm 6061-T6 aluminum.
     
  10. Barry
    Joined: Mar 2002
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    Barry Senior Member

    It appears that the posts are set into a recess as compared to being bolted in place.
    The boat manufacturer has chosen not to put a flange on the end and fasten it through the gelcoat.
    There can be quite a lot of strain/flex in the boat and by having the ends of the pole attached rigidly might cause cracking around the screws that you are considering using to stabilize them.

    It might be worth a call to the manufacturer and talk to the guy who designed this set up to see why they went this way
     
  11. snowbirder

    snowbirder Previous Member


    Giving myself a call right now. ;)

    I have some 6061t flanges on order through my local machine shop that is doing my tillers.

    I think this one is worked out for now... in power boat mode, anyway.
     

  12. Charlyipad
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    Charlyipad Senior Member

    FWIW, I glassed in a large dia. fir ply doubler on each side, with the aluminum flange thru bolted.

    Also, The nut on the bottom of the bridge deck would make a nice terminal for a grounding wire. I am thinking about attaching one that I can raise and secure somehow from the aft crossbeam, only to let it down at the dock or when in a thunderstorm.
     
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