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Windwiz on Spectra linesSubject: Re: Knots and line stretch (for sport kites)[From a 1993 posting I made to the rec.kites newsgroup. None of this is carved in stone, just my observations and methods of stretching and sleeving Spectra kite lines..] Line stretching and knot problems.. I've been following this thread about line stretch and knot problems with some interest and figured it was time to put in my $0.27 worth.. When I first started with this Spectra material, I went through a very parallel learning curve to that some of the folks out there on the net are experiencing now.. So what follows are some of my experiences gathered from making/selling pre-stretched, matched Spectra line sets.. If any of my customers or fellow flyers show any interest in making their own line sets, I'll show them everything I've learned, give them some sleeving material and a piano wire fid, then they can buy bulk line (from me or whoever), usually somewhat less costly than ready-made line sets.. First, I match the braided Dacron sleeving to the Spectra line as follows..
50# Spectra ---> 30# Dacron or I'll get some 3mm static line from a mountaineering shop and strip the core out of it and use the braided shell for sleeving for the heavier lines.. I cut the sleeving to 12" to 14" equal pieces.. Exact measurement isn't real critical but equality is.. I melt the ends of the dacron in a flame to keep it from unraveling, then using a fid of .010"-.015" diameter piano wire doubled over I poke the folded end of the piano wire through the side of the braiding sleeving just beyond the melted end and run it down the center of the sleeving, exiting through the side just before I get to the opposite melted end.. I usually string all four pieces of sleeving required for a line set on the fid before starting to sleeve the lines.. Next item is to measure/match/stretch the lines to length.. Because I make a fairly large number of line sets over the course of a season, I buy Spectra in 1000'-3000' spools.. The major advantage to this is that when I make line sets I'm assured that both sides of the set came from the same manufacturing batch and will have the same stretch characteristics.. If you buy 100' or 150' spools of line to make 100' or 150' line sets, you have no way of knowing that they came from the same run lot of line. Because of this, if your local supplier doesn't have bulk line available, get the longest spools you can (like 300') so you know that both lines came from the same batch.. To measure, I have a 100' fiberglass tape in my line bag, but pacing off the length will be OK for the average weekend flyer.. To pre-stretch the lines I use a stout piece of rope and a large carabiner(sp?), looping the rope around a lamp post or tree or trailer hitch and tying it off.. Clip the carabiner to the rope loop and pass the bitter end of the Spectra line through the carabiner. Then I use a screwdriver or stake as an axle for the line spool and wrap the end of the Spectra a few turns around the stake, and walk the line out to whatever length I'm making line sets.. For discussion sake, I'll use 100' for a number. At the 100'length, I'll cut the line away from the spool.. At this point I have a 200' piece of Spectra that runs from me to the carabiner and back to me with 2 bitter ends.. I pass the end of the Spectra through the loop in the piano wire fid that has the sleeving strung on it, double the Spectra over, and work off one piece of sleeving from the fid over the Spectra, running the sleeving a foot or so down the line. Repeat this for the other bitter end of the Spectra. Then I burn the ends of the Spectra to form a lump that's difficult for the sleeving to get back off of. Then I 'milk' the end of the sleeving even with end of the Spectra and grip both firmly then milk the opposite end of the sleeving away from the bitter end to make the sleeving fit as tightly as possible to the Spectra and tie off a loop with a figure-8 knot.. I've found that a figure-8 works better (for me) than stacked overhand or double overhand or surgeon's knot. Now I have the same 200' piece of Spectra, sleeved, looped and knotted at the bitter ends.. Now I'll again use the stake or screwdriver (round, smooth shank, please), passing it through the loops in the Spectra line and pulling with a smooth even pull enough to get the initial stretch out of the lines and holding some pressure on it for a little while.. Here's where some sense of feel comes into play.. Obviously, you can't lay into 50/80# line as hard as you'd get into 300# line.. One line manufacturer suggested to use about 50% of the line's rated strength as a stretch load. Now, stake the looped ends of the line (loosely, you'll need to get the other [bight] end off of the carabiner) and go back to where you started with the rope/carabiner combination. Unhook the spectra from the carabiner and use another stake to pull the line so it's even and this way you can find the exact center of the line loop and cut it into 2 _equal_ pieces. Sleeve the 2 new bitter ends as before and make loops with your choice of knot.. Now you have a pre-stretched matched set of lines that are ready to wind up, or fly with.. I find that all I use the Moran Equalizer for is to periodically check my work. Before winding or flying, I mark both ends of one line with a red magic marker to use as the left (or right) line, as your style dictates.. I know that most kite folks use red for right, but I've been around boats and aircraft all of my life, and red is the left navigating light under that convention.. Whatever your preference, if you use the marked line consistently for one side, then you don't have to stop and think about which hand is for which line, you can just pick up your lines and launch.. It's easier to fly the twists out of the line than to mess with them on the ground, IMHO..
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