Terminate backstay to over head radar arch?

Discussion in 'Sailboats' started by verbryck, May 23, 2019 at 12:07 PM.

  1. verbryck
    Joined: Yesterday
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    Location: long beach CA

    verbryck New Member

    Hi there, I'm in the process of installing a stainless steel arch over the back of my Ericson 39. I want the arch to mount solar panels, bimini etc... While I was looking at it the other day it occurred to me how much better it would be if I could terminate the back stay to the arch as opposed to having the back stay run through or in front of the arch down the transom. That is what brings me to this forum. I do not have the engineering background to determine if this is safe and or desirable to think about. I plan to use this boat for coastal cruising. The arch is made from 1.5 inch welded stainless steel tubing. The proposed termination point would be in line with the current trajectory of the back stay and approximately 5 feet off the transom. In any case I hope this is an appropriate place to pose such a query. Thanks for any insight into this question, George
     
  2. Blueknarr
    Joined: Aug 2017
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    Location: Colorado

    Blueknarr Senior Member

    Welcome to the forum.

    It could be done.
    BUT
    You will need to find an engineer who fully understands several disiplines. Most arch guys don't fully understand rigging or hull engineering. And versa visa.
     
  3. verbryck
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    Location: long beach CA

    verbryck New Member

    Thanks for the response do you know of anyone whom I could contact? Thanks, George
     
  4. upchurchmr
    Joined: Feb 2011
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    Location: Ft. Worth, Tx, USA

    upchurchmr Senior Member

    Forget it.
    There are so many ways to F... this up you might not believe.
    Starting with the strength of the hull where you attach the arch.
     
  5. verbryck
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    Location: long beach CA

    verbryck New Member

    arch backstay.jpg

    Here is a photo of a boat I found at the marina today illustrating how close the back stay comes to an arch. It seems like it would be so easy to just connect it to the arch and do away with the split stay running down to the transom. This arch is aluminum and is not welded so do not think it would support the load. Any engineers on this forum could explain to me the math I would need to use to figure out the loading for this type of arrangement? Thanks, George
     
  6. upchurchmr
    Joined: Feb 2011
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    upchurchmr Senior Member

    What you want on this forum is the equivalent of a Mechanical Engineering degree.
    No one with the qualification to design this will help here due to the liability when it fails and drops your mast in the ocean - or on your head.
    As Blueknarr said, it can be done - but it will be so heavy it would be silly.
    It will take a lots of material in the arch to get it stiff enough to actually provide anywhere close to the same support for the mast, even before worrying about the strength.
     

  7. gonzo
    Joined: Aug 2002
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    Location: Milwaukee, WI

    gonzo Senior Member

    Can you post a photo of the arch?
     
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