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| Replacing trap wires http://www.hobie.com/au/en/forums/viewtopic.php?f=9&t=3186 |
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| Author: | Beachboy [ Fri Mar 17, 2006 7:35 am ] |
| Post subject: | Replacing trap wires |
Anybody ever replace trap wires with high strength rope like New England Ropes' Spyder line? 1/8" rated at 578 lb. , 5/32 at 1358 lbs. tensile strengths. The black color gives good UV resistance (not like wire but the wire gets replaced from kinks) and the no kink, light weight would be welcomed. |
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| Author: | John Eaton [ Fri Mar 17, 2006 9:24 am ] |
| Post subject: | |
No but...I've read about people doing this and I'd also like to here from someone who has. Is the dyneema the equivalent to spectra? I was concerned about black color, specifically because of attraction of UV? |
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| Author: | Beachboy [ Fri Mar 17, 2006 9:31 am ] |
| Post subject: | |
According to the NE Ropes website the black has the best UV protection. I believe the outer layer is shielding the inner layer from light. The outer layer is polyester and black gives the best light blockage of all the colors. |
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| Author: | John Eaton [ Fri Mar 17, 2006 11:34 am ] |
| Post subject: | |
OK, answers that question. How about the rules? Paraphrased for trapeze; "existing" wires may be shortened or lengthened and adjustable systems added. Looks like a gray area not addressed. I certainly don't think using line is a loophole. |
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| Author: | Beachboy [ Fri Mar 17, 2006 12:53 pm ] |
| Post subject: | |
I doubt its legal for racing but not my concern. |
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| Author: | Hammond [ Sat Mar 18, 2006 10:52 pm ] |
| Post subject: | |
I am sure it can be done, but the question is why? The Hobie Magic 25 used spectra for trapeze lines, one common split to three seperate, but UV, chafe and long tern cost really beg to question why. Sure line does not kink, but neither do well cared for wires, so what is the real concern here? 
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| Author: | DougHobie17 [ Sat Mar 18, 2006 11:32 pm ] |
| Post subject: | Rope |
I have replaced my wire jib halyard with spectra to use on 190 sq ft reacher. I know this put a lot of load on it due to size of reacher and no problems so far. MUCH easier to coil than wire. Doug Snell Hobie 17 www.tcdyc.com |
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| Author: | Beachboy [ Sun Mar 19, 2006 9:44 am ] |
| Post subject: | |
At $20 for 75 feet for the 2.8mm 1200 lb test (West Marine) the cost is not an issue. Actually cheaper than new wires I think. We are recreational sailors, not racing, that may explain a lot. The traps are rarely used, mostly now for mast stepping. The old ones neeed replacing. They are very unfriendly to the ungloved hand, tend to get kinked in storage, prone to destruction from the environment, a PIA to rig, i.e. I've got to buy the wires made up, the rope I can rig myself and change if I want to, same goes if one fails; on the beach fix. Try that with wire. It's lighter and non-conductive too. The casing won't peel off slowly. Does not need to be rinsed after salt exposure. No corrosion from dissimilar metal contact. I can very easily see when a rope is wearing out and in need of replacement. No sharp edged metal connecting hardware required. The wires can fool you with disasterous results if you are not diligent with inspection for cracks, corrosion. If you are interested in speed, rope is much lighter. That's all I can think of right now. The concept is this. Because of kevlar and other synthetic fibre technology we now have ropes that can perform what formerly only wires could do in the same size/stretch/strength categories. |
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| Author: | John Lunn [ Sun Mar 19, 2006 6:30 pm ] |
| Post subject: | Spectra/Dyneema article from Kanata Sailing Club newsgroup. |
Hi You'All, HMDPE (Spectra and Dyneema) High Molecular Density Polyethylene is a remarkable material. With today’s new high-tech synthetic fibers and advanced rope construction, you can buy rope that’s 10 times stronger than steel with extremely low stretch. Many racers and cruisers have switched from wire to all-rope halyards; others have also opted for high-strength, low-stretch, lightweight ropes for their running rigging. All-rope halyards have several advantages over wire. Hand-over-hand hoisting is much faster than all-wire; it’s safer, too. Wire is hard on your hands and gear. Rope is easier to splice, it won’t scrape paint or anodizing from your mast, and you don’t have to decide whether or not to rely on a worrisome rope-to-wire splice. Quality rope costs more than wire but is easier to install, lasts longer, and can be recycled in a less demanding capacity. Spectra and Dyneema are simply different brand names for the same thing made by two different companies. Although Spectra and Dyneemra have significant advantages, here are serious disadvantages: A frustrating disadvantage of HMDPE-based Spectra & Dyneema is that though the initial stretch of HMDPE is very low, if one leaves a HMDPE rope loaded for a long time it slowly but inexorably stretches, never to return to its original length. While this is not a problem in lines that are adjusted regularly, it is not appropriate in fixed lenght ropes such as shrouds. Therefore, Spectra & Dyneema are not recommended for Shrouds or Forestays. The exact size and type of rope used is critical to the performance of any rope holding device. While some of the smaller types of cleat work well with laid (twisted) rope, the majority work best with a woven construction. Twisted HMDPE ropes do not incorporate covers to protect them against UV and so they deteriorate too quickly when used on sailboats that are constantly exposed to sunlight. Woven ropes bring their own problems. While the part of the rope in contact with the holding device is the cover, the bit doing the work is the core down the inside. Slippage between the cover and the core can be a limiting factor in holding power if the rope is not well made. Better quality ropes often have an intermediate binder layer incorporated between the core and the cover to help transfer the load; this is certainly a good thing to look for in a rope to be used in a highly stressed situation. The precise way in which the cover is attached to the rope is critical, as it is essential to ensure that the cover pulled down tight to ensure good load transfer back into the original rope. A neat taper into the original rope is also essential if the join is not to snag in blocks. In the case of lines that will have to be made off in more than one position (e.g., halyards for sails that reef) it is important to make sure there is a additional cover at every wear point. Under load, the core will slip through the clutch inside the cover, so the cover has to be sewn to the core in the area in which the clutch is likely to hold it. Another serious disadvantage is that HMDPE rope is thicker, so it may cause problems for the KSC's boats which have halyard hardware for smaller lines. Replacing the hardware is a possibility though... Also, Spectra or Dyneema braided-core halyards often are stripped of their covers over the length that isn’t handled or exposed constantly to the sun, and the stripped part functions well in a clutch of appropriate size because it’s effectively now a single-braid and the HMDPE fiber is highly resistant to wear. Also, one must avoid using knots to terminate high-modulus lines. Any knot or bend that comes under load lowers the breaking strength of any line in which it’s tied. In high-tech lines, the reduction can be dramatic. Knots can also slip out of slippery Spectra. All manufacturers and riggers recommend splicing—say, to halyard shackles or sail clews—as being far more reliable. The type of splice used depends on the lay of the line. Most rope manufacturers offer splicing kits and manuals, and the winter-bound sailor might consider periodically practicing with them. Otherwise, it’s best to have splices professionally made which removes one of the advantages of high tensile rope over metal. Splicing services for rope to hardware costs $50 to $100 per splice depending on the kind required. Therefore, use of Spectra or Dyneestra for halyards are a complicated affair and may not be appropriate for the KSC... Vectran, is the latest in a line of high strength materials and incorporates the latest improvements to Spectra and Dyneestra. Vectran looks like an almost perfect rope maker's material. However, it is as you might expect frighteningly expensive. However, there are applications where a little bit of give can be a good thing and where the KSC may use Spectra or Dyneestra. Anchor warps are the obvious example but there is a place for some shock absorption in other places too, like trapeze wires. And that is my GOOGLE search for today... SALUT! Pierre. |
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