Problem with Snap Swivel

edited January 2009 in General
Problem with Snap Swivel

I have been using a snap swivel that I purchased from a fishing tackle store to attach my line to my delta kite. When buying it I was told that it would hold 400 pounds in weight. However when I was flying my kite at the weekend the catch in the snap swivel opened when the wind picked up and my kite separated from my line, as I was flying at a coastal area, it landed in the sea and I was unable to retrieve it! Has anyone had similar problems with snap swivels? Should I Purchase mine from somewhere else made especially for kites?

Any advice would be much appreciated. Amy

Comments

  • WHOA!

    I've been using snap swivels I got from Brooks with my kite line order, and ones I got from kitebuilder.com. No problems with either of them, but your story does have me looking at my setup and wondering about single points of failure. I know a lot of people don't use snap swivels for just that reason. I guess I just haven't been burned yet.

    Tom
  • edited June 2012
    There are two main types of swivel, one relatively safe, one not at all (for KAP) no matter what its rating.

    The Rosco or Coastlock swivel hooks around itself. Under excessive strain, it will just slide into a smaller loop.

    image

    The standard (cheap) swivel has a flat brass sleeve into which the open end is slid. Very insecure and should be avoided.

    image

    Contact me, Amy, and I'll send you the right one. Tell me what kite you want to fly so I can size it appropriately. email is in my profile.

    http://www.brooxes.com/
  • edited January 2009
    I had a snap swivel fail that way 6 years ago - I think I'd bought (like the cheap one in Brook's post) some without realising how tough they needed to be. As a result I bought some really tough ones (300lb plus) and have never had a problem since (except once when I forgot to snap one closed!). However I only use them when flying in very light winds and 150lb line. My 250lb line has a simple loop at the end and I just form a larks head to go over the ring at the end of my kite bridles.

    Dave
  • edited March 2009
    I find the loop converted into a larkshead to be pretty convenient. It can go over a ring or it can go over a secure knot and you can use it like the swivel to secure the end of the line to the hoop for storage.
  • I am one of those that does not use snap swivels to attach the flying line to the kite. I use them to attach tails
    and such but not the line. The thing with a mechanical fastener is that eventually it will fail. After opening and closing them enough times they will fail. Especially if you have to open them any extra ammount to get them over webbing, a ring, or a thicker reinforced kite anchor point. They will give you no warning before they fail. They don't look frayed as a sign of wear. One moment they look fine. The next they have failed and if your camera is up there it is now a catastrophic failure. Lots of bad things can happen that you can recover from but not a seperation of line and kite.
  • Dave, can you post a picture of how you larks head onto a ring that's attached to the kite bridle? I'm not picturing that.
  • edited January 2009
    This thread is making me do some hard thinking. I just moved my #100 line from one winder to another, and as I was putting on my snap swivel (a Rosco I got from Brooks), I came back to re-read this thread.

    Two thoughts I'd like some input on:

    1 - My wife pointed out that any piece of hardware we use at work that has a finite lifetime is periodically replaced as part of our preventative maintenance program. Would a snap swivel be more reliable if it was replaced once every X months or once every X flights, or would that just set you up for running a higher risk of encountering a bad snap swivel because of manufacturing defects?

    2 - I tie my line to my snap swivel with a bowline, and could just as easily do as tgran does, and tie the bowline to the kite ring each and every time. They're pretty easy to untie, they don't tend to shake loose when line tension is off, and they don't degrade line strength much. But does this set me up for periodic failures because I get careless tying a knot?

    I'm guessing at this point at least a goodly portion of people are throwing up their hands and saying, "Come ON! NOTHING is risk free!" And you're right. But I don't see any right answer in all this. No matter how it's attached, it's still a single point of failure.

    For what it's worth, I haven't had a snap swivel fail and I've never had a knot on a kite line fail, but I have had all three bridle lines on a Flowform separate from the ring at the same time. I wasn't flying in high wind, I wasn't doing anything I shouldn't have done, and thank goodness I didn't have a camera clipped on. The kite deflated, fell to the ground, and I re-tied my bridle lines. No losses, and no problems since. I do check my bridle lines periodically, and didn't see anything indicating a failure was imminent except that there was very little tail after the knot. I think the line just pulled out. This is how the kite came. I like to leave some tail after the knot so I can see if things are shifting, and do a tug-test to see if the knot is holding. This is how my bridle lines are now tied. Still, the experience was nerve-wracking. I don't trust knots any more than I trust snap swivels.

    Tom
  • David: you slide the larks head over the ring so that it is tightened on the bridle lines.
  • edited March 2009
    Difficult without pictures. EDIT: PICTURES HERE.

    The loop on the end of the line stays tied the whole time. Push a bit of line through the loop to form a new loop. As you tighten the new loop down (moving the knot part of the loop out of the way) it becomes a larkshead knot. You can slide it over the ring on your bridle lines and secure it right behind it. Geometrically the line is attached perpendicular to the bridle lines -- but the wind will fix this. The larkshead is a slip knot and holds well under tension -- but it is loosened easily on the ground. It takes a few seconds to switch the line to another kite. The load should be entirely on the larkshead knot. The first loop knot is just a way of making a stable loop that's easy to keep track of. If you use a bowline for your loop remember it is not good by itself under intermittent load.

    For the bridle I don't use a ring and instead larkshead a short length of heavy line (stuff from the REI climbing section I use for shoe laces) to the tow point. I then pull the dangling ends together and put a stopper knot (double overhand) in the shoe laces. I slide the larkshead from the flying line over this obstruction and tighten it down on the shoe laces right behind the stopper knot.

    There used to be an AOL hosted site which had nice pictures, but I think it's still down. I think this is a pretty common way of working with lifting kites and sport kites. It's basically this guys technique. EDIT: Actually that's a little different isn't it :)

    You do have to trust your knots. I like to add extra stopper knots so lines can't slip through and/or fasten dangling ends back to the lines. I stick to a few knots and make heavy use of the larkshead and prusik.
  • The Bowline is a great knot, but not foolproof. Unless you "lock" it by tying a single overhand knot with the loose end around the adjacent loop, it can come apart with alarming ease. I much prefer the Half Blood Knot for attaching a line to a swivel --- very easy to tie and untie, even after tension. You'll find it on the Knots sheet on my Downloads page.

    Certainly, Tom, it wouldn't be a bad idea to replace swivels occasionally. I don't until they start to lose their finish, and I've never had a failure.

    Craig, mechanical devices can fail eventually, of course, but so will the line itself. How often do you replace your flying line, or tie a fresh loop, or turn the line end for end?

    http://www.brooxes.com/
  • Brooks, I do replace my line I use for KAP about every 4 years or so or when I notice it has been damaged or shows signs of wear. I guess my point is that it is really difficult to detect when a piece of metal is near failure. Its easy to see when your line is worn and should be replaced.

    In addition for me, #1 I like to tie the knot as it forces me to slow down and examine the line and the connection point of the kite as I tie on. Its part of my preflight ritual. I'm a Boy Scout- I like knots. #2, The snap isn't any easier. #3, When winding up the line I don't like dragging the snap through the grass/sand/dirt/ pavement/corn stuble. #4 it adds weight. #5 I see no added benefit in adding them, only the addition of another something that can fail. (the swivels on my tube tails have all failed at some point in the 22 years I have had them) But this is just my opinion. I have no proof.
  • I have great faith in the Coastlock snaps. Flying a FF16 in heavy gusts down in the BVI I had a 200# Costlock deform to the point it was closed up against the bridle loop but it didn't open. I have learned since then to pick the appropriate kite for the wind. :-)
  • edited January 2009
    Here's how I put the swivel on the line. First tie a loop knot at the end as described at brooxes site. I'll also tie a stopper knot at the end before making that loop knot just in case the line decides to slip.

    After that, attaching the swivel is easy:
    image
    image
    image
    image

    I learned the bowline when learning to sail. In sailing it's a good knot because it is easy to untie when the line doesn't have a load on it. This is probably less of an issue with thinner kite line, but I opted for a knot that was difficult for me to untie even when the line was loose.
  • edited January 2009
    @David Wheeler: This is how I've done the larks head over a bridle ring.
    image
    image
  • Dave, can you post a picture of how you larks head onto a ring that's attached to the kite bridle? I'm not picturing that.
    You should also get rid of the o-ring. Just tie a knot in it's place and larkshead the kite line to it. Rings just are not good. The wear down the line and can also rust which weakens the line.
  • That picture by Scott Dunn shows what I meant to say. I leave the rings on my bridles, but I keep an eye on them. No sign of rust.

    I should also say that both the ring and the bridle line are much more over-engineered than the main kite line. I've never had a failure there (touch wood).
  • edited January 2009
    Thanks for all the advice and instructional images, I'll have lots of ways attach my kite that hopefully wont fail again!
    The one lucky thing when it happened was that I had not attached my camera yet, so at least I did not loose that 2
  • Thanks, everyone for the larkshead - ring pictures. That's a really neat technique I wasn't aware of. Until now I've been tying the flying line to the ring with a bowline.
  • David, I too used a bowline to the ring. I think now I will try the larkshead (or is it the double larkshead - I will find out).
  • edited March 2009
    Redberry, if you read Broox above you'll note that the bowline can untie under tension.

    To be less verbose than I was above . . . I use sdunn's method (loop knot --> push line through to form larkshead --> tighten above ring). Easy on, easy off. A "giant larkshead" tightened on the halo and rotated the correct direction will keep your line from falling off during transport or storage.

    I put up some images on the flickr tutorial site.
  • edited March 2009
    Let's say for example that I do not want to use a swivel (and I'm undecided on that), but I have managed to comprehensively twisted my line, putting on a swivel one time to undo the twist would be ok, wouldn't it? I mean this if you are anti-swivel.

    edit:

    Found these on eBay: (which size would be suitable for Rok and FF16 with 100kg Dacron?)

  • edited March 2009
    Tim - see your email in-box - I have some to spare.

    Dave
  • The nominal strength of Coastlocks is:
    #7 - 75 lb.
    #5 - 90 lb.
    #3 -100 lb
    #1 - 150 lb.
    2/0 - 225 lb.
    4/0 - 350 lb.
    That must be the load at failure because my FF16 has straightened out a #1. It stayed hooked but the loop shrank up to a small eye. I have gone to stainless rings on the bridals and a long blind eye splice on the line. Form a double loop in the eye, slip the ring through and you have a larks head.
  • Dave, got your email, thanks. Glenn - useful info that, I hadn't seen this info. A 100kg line would need a '2/0' by the look of it. (100kg=220lbs)
  • Air Affairs recommends lighter line than I do on Flow Forms, e.g., 150# for the 16.

    I recommend 200# line with a 2/0 Coastlock swivel. I've straightened one on a FF30, but not on a 16.

    http://www.brooxes.com/
  • edited April 2009
    I got a couple kites for my birthday last weekend. Neither are good for KAP. But, the ITW Elevation Box has a recommendation for 150# line. So, I ordered some 200# line from Brooks and it got here faster than it could be tracked. Anyway, the box kite tow point looks like a larkshead should be used. I was trying to figure out how to use the swivel on the line for other kites if I wanted to. Then, I remembered some photos in this discussion.

    sdunn, your photos solved what I was trying to figure out. I can tie a loop knot on the end of the line. The loop can be used for a larkshead on some kites and I can attach the swivel like you showed using the same loop.
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