Page 2 of 3 FirstFirst 123 LastLast
Results 11 to 20 of 24
  1. #11
    Senior Member Rain Man's Avatar
    Join Date
    Nov 2007
    Location
    Nashville, TN
    Hammock
    Hammeck Netty
    Tarp
    HG dyneema/MacCat
    Insulation
    DIY UQ and UGQ TQ
    Suspension
    whoopie slings
    Posts
    2,907
    Images
    8
    Quote Originally Posted by Knotty View Post
    Breaking point is at about 80% of the lines rating.
    Knotty, not to argue, but Samson's site says 60%.
    "AmSteel® and AmSteel®-Blue Whoopie Slings have a break strength of 60% of the published average ROPE break strength."

    For what it's worth.

    Rain Man

    .
    "You can stand tall without standing on someone. You can be a victor without having victims." --Harriet Woods

    http://www.MeetUp.com/NashvilleBackpacker
    .

  2. #12
    Senior Member Knotty's Avatar
    Join Date
    Mar 2009
    Location
    Denville, NJ, USA
    Hammock
    DIY Stretch-Side
    Tarp
    DIY Cat Cut Hex
    Insulation
    Phoenix and Nest
    Suspension
    cinch buckles
    Posts
    4,377
    Images
    227
    Not argumentative at all my friend. A while back I contacted Samson to ask them about whoopie slings and this is what they said.

    http://www.hammockforums.net/forum/s...ad.php?t=12319
    Knotty
    "Don't speak unless it improves the silence." -proverb
    DIY Gathered End Hammock
    DIY Stretch-Side Hammock
    Stretch-Side "Knotty Mod"
    DIY Bugnet

  3. #13
    Senior Member
    Join Date
    Jan 2011
    Location
    IN
    Hammock
    WBRR, Lots of DIY
    Tarp
    MacCat; Cloudburst
    Insulation
    Lynx, HG T/UQ, AHE
    Suspension
    Varies
    Posts
    8,464
    Quote Originally Posted by Knotty View Post
    Not argumentative at all my friend. A while back I contacted Samson to ask them about whoopie slings and this is what they said.

    http://www.hammockforums.net/forum/s...ad.php?t=12319
    So...with a "working load" of 20% (per Samson's site), we have 1600 x 0.8 x 0.2 = 256 lbs rating. Not quite the 1600 lbs commonly referred to.

    It still works for me.
    Last edited by gmcttr; 04-20-2011 at 11:58.

  4. #14
    Senior Member
    Join Date
    Dec 2007
    Location
    Doraville, GA
    Posts
    946
    Images
    23
    Quote Originally Posted by gmcttr View Post
    So...with a "working load" of 20% (per Samson's site), we have 1600 x 0.8 x 0.2 = 256 lbs rating. Not quite the 1600 lbs commonly referred to.

    It still works for me.
    I thought that using 20% of static rating to come up with a safe working load (SWL) took into account using knots. A quick look at that bulletin reveals a typical 50% reduction due to knots is likely used to come up with the 20% derating factor. So wouldn't replacing a knot with a whoopie sling increase the SWL?
    Youngblood AT2000

  5. #15
    Senior Member
    Join Date
    Jan 2011
    Location
    IN
    Hammock
    WBRR, Lots of DIY
    Tarp
    MacCat; Cloudburst
    Insulation
    Lynx, HG T/UQ, AHE
    Suspension
    Varies
    Posts
    8,464
    Quote Originally Posted by Youngblood View Post
    I thought that using 20% of static rating to come up with a safe working load (SWL) took into account using knots. A quick look at that bulletin reveals a typical 50% reduction due to knots is likely used to come up with the 20% derating factor. So wouldn't replacing a knot with a whoopie sling increase the SWL?
    Yep...I was wrong (again). Thanks for the correction.

    After re-reading, I see that the SWL takes into account "appropriate splices" and therefore it would simply be 20% of the rated strength.

    FWIW...I was not advising against whoopies. I use 'em and love 'em.

  6. #16
    Senior Member Knotty's Avatar
    Join Date
    Mar 2009
    Location
    Denville, NJ, USA
    Hammock
    DIY Stretch-Side
    Tarp
    DIY Cat Cut Hex
    Insulation
    Phoenix and Nest
    Suspension
    cinch buckles
    Posts
    4,377
    Images
    227
    Always important to understand safe working load. Too many people think that all they need is a line that's rated for the static load. That leaves no margin of error for wear, shock load, point load, etc.

    I don't know the official way to calculate SWL with rope but my goal is to have a 5:1 safety factor after accounting for knots and splices. So stealing gmcttr's equation, 1600 x 0.8 x 0.2 = 256, tells me 7/64" amsteel is good for most people.

    People have had good success with Dynaglide (1000#?) but for me there's just not enough safety factor there.
    Knotty
    "Don't speak unless it improves the silence." -proverb
    DIY Gathered End Hammock
    DIY Stretch-Side Hammock
    Stretch-Side "Knotty Mod"
    DIY Bugnet

  7. #17
    Senior Member
    Join Date
    Jan 2011
    Location
    IN
    Hammock
    WBRR, Lots of DIY
    Tarp
    MacCat; Cloudburst
    Insulation
    Lynx, HG T/UQ, AHE
    Suspension
    Varies
    Posts
    8,464
    Quote Originally Posted by DawgU View Post
    Thanks! I'll give it a try.
    We now return you to your regularly scheduled programing.

    DawgU...any luck stopping the whoopie slip?

  8. #18
    Senior Member Rain Man's Avatar
    Join Date
    Nov 2007
    Location
    Nashville, TN
    Hammock
    Hammeck Netty
    Tarp
    HG dyneema/MacCat
    Insulation
    DIY UQ and UGQ TQ
    Suspension
    whoopie slings
    Posts
    2,907
    Images
    8
    Quote Originally Posted by gmcttr View Post
    So...with a "working load" of 20% (per Samson's site), we have 1600 x 0.8 x 0.2 = 256 lbs rating. Not quite the 1600 lbs commonly referred to.

    It still works for me.
    I would like to know if that "working load" is for lifting "stuff" only, or if it also applies where human safety is involved. Often (I think), those are different and not interchangeable. In skimming the article, I didn't see yet which that rating applied to. (NOTE: Found it... see bottom below.)

    I did note something else interesting and applicable, however:

    "When given a choice between ropes, select the strongest of any
    given size. A load of 200 pounds represents 2% of the strength
    of a rope with a breaking strength of 10,000 pounds. The same
    load represents 4% of the strength of a rope that has a breaking
    strength of 5,000 pounds. The weaker rope will have to work
    harder and as a result will have to be retired sooner."

    Anyone retire their whoopie slings sooner when lower rated Amsteel is used? Otherwise, we are cherry picking the bits and pieces of data we want, or so it seems to me.

    I do note something else very interesting in that article:

    "Our published strengths and test results reflect as accurately
    as possible the conditions under which they are to be used.
    Because all ropes are terminated with a splice, all published
    strengths herein are spliced strengths."

    That means we don't have to take into account how much a splice reduces the strength of Samson Amsteel, because they have already done that?

    I think I found the answer to my question about whether Samson's ratings are good for human safety. Apparently not:

    "Working loads are the loads that a rope is subjected to in
    everyday activity. For rope in good condition with appropriate
    splices, in noncritical applications and under normal service
    conditions, working loads are based on a percentage of the
    approximate breaking strength of new and unused rope of
    current manufacture. For the products depicted in this catalog,
    and when used under normal conditions, the working load
    percentage is 20% of published strengths."

    Their ratings are good for "noncritical applications," which means they can not be used for determining safety in hammock hanging, as I see it.

    Rain Man

    .
    Last edited by Rain Man; 04-20-2011 at 22:54.
    "You can stand tall without standing on someone. You can be a victor without having victims." --Harriet Woods

    http://www.MeetUp.com/NashvilleBackpacker
    .

  9. #19
    Senior Member Knotty's Avatar
    Join Date
    Mar 2009
    Location
    Denville, NJ, USA
    Hammock
    DIY Stretch-Side
    Tarp
    DIY Cat Cut Hex
    Insulation
    Phoenix and Nest
    Suspension
    cinch buckles
    Posts
    4,377
    Images
    227
    Rain Man - I believe the standard for life safety is a 10:1 margin. For hanging a hammock 5:1 seems reasonable. If you want to play it extra safe consider using 1/8" instead of 7/64". Still not 10:1 but moving in that direction.

    PS - DawgU, sorry if we've strayed too far off topic.
    Knotty
    "Don't speak unless it improves the silence." -proverb
    DIY Gathered End Hammock
    DIY Stretch-Side Hammock
    Stretch-Side "Knotty Mod"
    DIY Bugnet

  10. #20
    Senior Member
    Join Date
    Dec 2007
    Location
    Doraville, GA
    Posts
    946
    Images
    23
    Knotty, I recall that the packaging that came with rope I bought in the past said the SWL was between 8% and 20% of the breaking strength, depending on application... but if it was for life support that you want to further derate it.

    I figure that we give our hammock suspension lines a lot of inspections, pretty much every time we hang them and take them down, so I feel okay with the 20%. When I first started hammocking I used 3 strand, twisted polypropylene rope because that is what I thought I saw on a Clark Hammock but changed to braided rope after I saw one of the 3 strands kink where the slippery bowline had been tied because that meant only 2 of the strands were supporting the load. You have to keep your eyes open when you go light weight.

    This dyneema cordage is some amazing stuff. I found this bulletin the other day that has info about tension fatigue http://www.samsonrope.com/site_files...tic_Ropes_.pdf
    Youngblood AT2000

  • + New Posts
  • Page 2 of 3 FirstFirst 123 LastLast

    Similar Threads

    1. Alternative to whoopee sling....
      By D.O in forum Suspension Systems, Ridgelines, & Bug Nets
      Replies: 11
      Last Post: 08-22-2012, 04:49
    2. Replies: 17
      Last Post: 05-03-2012, 16:27
    3. Whoopee! My 20F Burrow arrived today
      By Phillipsart in forum Hammock Gear
      Replies: 15
      Last Post: 09-24-2011, 05:04
    4. bury lengths for 1/8 in whoopee
      By nothermark in forum Suspension Systems, Ridgelines, & Bug Nets
      Replies: 11
      Last Post: 07-28-2011, 17:30
    5. Looking for whoopee slings
      By domromer in forum Archived WTB
      Replies: 7
      Last Post: 08-10-2010, 17:56

    Tags for this Thread

    Bookmarks

    Posting Permissions

    • You may not post new threads
    • You may not post replies
    • You may not post attachments
    • You may not edit your posts
    •