Hammocks and stress on standing rigging - Page 2 - SailNet Community

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  #11  
Old 08-07-2011
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WDS123 is on a distinguished road
Gary,

Brilliant insight, you are most certainly correct there could be significant bending moments induced depending on various aspects of the loads. However, if the the shroud connections are able to rotate ( aka pin connection ) then the bending moments are not as relevant.

1x19 wire ? If people think they are not hurting the life by hanging on 1x19 wire than they are wrong.

My image was of a off shore passage maker with hammocks hanging somewhere above crystal blue waters
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Old 08-09-2011
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WD,
I think you may have misunderstood, I wasn't even considering bending loads. Have you ever 'sweated' up a halyard on a small boat that doesn't have halyard winches? If you pull hard against a slack halyard you hardly add and tension at all. If you pull the halyard tight and then pull outwards at right angles you can create tremendous tension. A hammock is a really bad case, because you have two sources of mechanical advantage. You can tie the hammock to the rigging with it pulled very tight and almost no sag. When you add your weight to it is multiplied many times as the hammock sags. Then that pull goes into a stay which is taut, and it multiplied yet again.

I once got a heavy truck stuck in the mud, and our big digger derrick with 4 wheel drive couldn't pull it straight out. So we attached a steel cable to the truck and to a large tree and pulled it tight. We then used the four wheel drive truck to pull at right angles to the cable, multiplying the force many times. The stuck truck moved easily a short distance. Then we tightened the cable and pulled at right again, until we got it our.

I hope this makes clearer what I was trying to say.

Gary H. Lucas
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Old 08-10-2011
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Gary, The shroud is already tensioned pretty tight. It deflects very little when I swing myself aboard using it as a hand hold, and it doesn't bend locally to any significant degree as I do so. What you say about leverage is true. At the limit of infinitesimally small angles, you would have near infinite leverage.

But we're talking about a hammock. Never mind that the shroud is much stiffer and less stretchy than the hammock and its ropes. Your hammock isn't infinitely strong, and we don't generally worry that climbing in will overstress and shred them, whatever you tied it to.
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