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  1. #1
    Member OrangePeel's Avatar
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    At what body weight is 7/64 Amsteel not enough?

    Hi all,

    My ENO DoubleNest is coming in tomorrow and I was thinking about heading to West Marine to pickup some Amsteel and make some whoopie slings. Then I remembered reading about all of the angles and weights suspension systems can see and it made me wonder... is 7/64 enough? At what body weight, if any, should I use 1/8 instead?

    Thanks,

    Brandon

  2. #2
    Mr. Arrowhead pgibson's Avatar
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    We have done 24 hour continuous dynamic load testing to 600 pounds on 7/64 in house. Another vendor has had lab testing done to breaking point, failure was at full rating. Unless your going to host a small party in your hammock, you know with a band, 3 kegs, those what's up guys from 2004.........Sorry its getting late and dis not sleep well last night.......You will be fine with 7/64.
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  3. #3
    Member OrangePeel's Avatar
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    LOL... thank you for the imaginative reasoning.

    I wasn't sure if they would be put under more than just my body weight or not.

    Brandon

  4. #4
    Senior Member SGT Rock's Avatar
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    If I remember correctly 7/64th Amsteel is rated to about 1600 lbs. So if you went by the 1:5 rule of thumb, that makes it good to about 320 pounds.
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  5. #5
    Member OrangePeel's Avatar
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    Sweet... I'm 70 lbs below that. What is the 1:5 rule of thumb?

    Brandon

  6. #6
    Gresh's Avatar
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    Quote Originally Posted by OrangePeel View Post
    Sweet... I'm 70 lbs below that. What is the 1:5 rule of thumb?

    Brandon
    Whatever you're using, you want it to be able to support five times your weight. I use 1/8 Amsteel.
    Vice-Chairman, Palmetto State Hangers

  7. #7
    Senior Member DemostiX's Avatar
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    Do a bit of search on engineering safety margins for cordage. IMO, Sgt is being liberal. A margin of 5 to 1 is for non-human support, so 5 to 1 will be the ratio of strength to maximum working load for such as tow ropes and straps. 10-15 to 1 is the safety margin for human loads.

    On the other hand, and it is a strong hand.
    • The load is almost shared by two cords, each bearing about half the weight.
    • Engineering conservatism appropriately assumes that the cord will be terminated in knots which will compromise the strength by 40-60%. On average ,then, there's a need for cord that is twice as strong as its maximum expected static load. However, and in contrast, you will find in HF everywhere, descriptions of proper splicing methods for (hollow braid) Amsteel, which result in no more than a 10% strength loss from terminations. So, that source of risk to safety is minimized. Further, IIANM, the rating on Amsteel from Sampson Rope is already of a properly spliced line.

    Last edited by DemostiX; 11-16-2012 at 00:45.

  8. #8
    Member OrangePeel's Avatar
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    Ahhh... I see... thanks for the explanation.

    Brandon

  9. #9
    MAD777's Avatar
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    If you hang your hammock with the suspension angle at 30 degrees to the horizon, the tension on each end of the suspension is equal to your body weight.

    So, if you weigh 250# and your hang angle is 30 degrees, then each end will be supporting 250#. If 7/64" Amsteel will support 1600#, you have a safety factor of about 6 times the your load.

    Or as Paul Gibson mentioned in the first answer to this thread, you can invite 5 friends to the party, but leave the kegs outside the hammock
    Last edited by MAD777; 11-15-2012 at 09:39.
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  10. #10

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    Quote Originally Posted by DemostiX View Post
    Do a bit of search on engineering safety margins for cordage. IMO, Sgt is being liberal. A margin of 5 to 1 is for non-human support, so it 5 to 1will be the ratio of strength to maximum working load for such as tow ropes and straps.

    On the other hand, and it is a strong hand.
    • The load is almost shared by two cords, each bearing about half the weight.
    • Engineering conservatism appropriately assumes that the cord will be terminated in knots which will compromise the strength by 40-60%. On average ,then, there's a need for cord that is twice as strong as its maximum expected static load. However, and in contrast, you will find in HF everywhere, descriptions of proper splicing methods for (hollow braid) Amsteel, which result in no more than a 10% strength loss from terminations. So, that source of risk to safety is minimized. Further, IIANM, the rating on Amsteel from Sampson Rope is already of a properly spliced line.

    Not to be too picky but anywhere I was involved the safety rating would be 5x the derated limit. In other words if the knot used created a 60% loss in strength 1600 lb amsteel with that knot would be 1600 x 0.4 /5= 128 lbs. That is why one does not replace splices with knots. ;-)

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