Anyone have a cheap alternative to dyneeva or something of the sort for say 30 ft. of nylon rope in a 1" dia? I know this may pertain more towards yachting but I figure many of you are into that as well so I thought I’d give it a try!!!
The standard is used firehose. But even the smallest diameter might be a bit large for yacht line dimensions. Something not to expensive and nice looking is the clear plastic water hose with the criss cross white threads embedded.
Michael
Care must be taken in the use of chafe guards especially with nylon rope. Particularly when it gets wet, nylon is well known to deteriorate and fail. Therefore chafe guards such as hose are not normally recommended because it allows heat to develop and hastens the breakdown of the rope. Canvas or leather are preferred as they let the rope breath. There was a study done at MIT regarding this.
Larry
Hi Larry,
Could you let us know where we might see a copy of the MIT study you mention? It would be very interesting to the technical wonks among us,
;D
SR
SR,
I saw it mentioned in a Boat US publication, “Seaworthy” Vol 23 No.2, April 2005.
Unfortunately, it was in an article about anchoring boats in a Hurricane and merely states that tests at MIT after hurricane Bob confirmed an experience of rope failure where fire hose had been used for chafe protection. Long story short: 2 boats, one used fire hose, the other used denim fabric. The one failed and it was found that the rope was reduced to globs of melted nylon. The reason is believed to be that the heat generated by tension on the line is greater because there is less lubrication and dispersion of heat by water and additionally the rope could not breathe and dissipate the heat. Interestingly enough, they say MIT found that this is most evident in heavy cycling and that dry nylon works better in light cycling. It appears that the failure occurred where the anchor rode went through a bow chock. They state that MIT came to the conclusion that the best way to handle the situation would be to use polyester from the cleat through the chock - less stretch and better abrasion resistance. The balance should be nylon for its desirable stretch. Lastly, they recommend joining the 2 ropes with eye splices in each line. It isn’t too clear but I think they pass the nylon loop through the polyester one then the end of the polyester through the nylon loop.
There is also a distinction between docking and mooring. The different lead of the dock line results more often in external damage from chafe than from the internal damage by heat. However, I was one time told be someone who did a test by pulling on nylon rope in a straight line that heat caused internal failure when subjected to high tension.
I believe that Brion Toss mentions the nylon - polyester approach in “Riggers Apprentice”.
Also, I recall recent mention of this problem of heat destroying nylon rope in a recent post to the forum involving putting heavy loads on tow lines in the tug boat community.
Larry
Re Nylon rope at high tension: an aside.
I remember an TV article about a small town in USA going for a Guinness record for a tug-of-war. They got a couple of thousand people and a very long nylon line and laid it out. At the signal they all pulled as hard as they could. The result was a lot of them suffered sever burns to their hands. True story
Re chaffing: I recently saw a boat that had put extra lines (3/4 braided polysomething) to the dock and just laid them over the cap rail with no chaffing gear. (Couldn’t believe it!!) The cap rail was softwood (Fir) and the line didn’t chaff but rather wore a large part of the cap rail into deep groves. Not good seamanship…
Hello again Larry,
I am amazed that MIT (well, maybe MIT, on account of there being nobody there that understands sailing) would recommend putting eye splices together as part of an anchor rode - how do the joined eye splices move through the gypsy or cathead? Seems like a dubious recommendation to anyone who has attempted to retrieve nylon rode to re-set in the middle of the night when they have gotten too close to shore and need to get further out - imaginer the clusterf**k when those eye-splices get stuck in the retrieval equipment! Brion Toss does have a recommendation for attaching a snubber (altogether a different animal) to a rode, and he does not mention attaching two eye-splices together, but does discuss using nylon or Dacron (polyester) for rode in combination with chain. He even, for those who can afford it, recommends using Dacron for rode when combined with a snubber. Brion also discusses the speed of nylon line that has just snapped as being some 700 feet per second - that’s nearly 480 mph for those who want some idea of jet plane speed to compare with! Better stay clear of any loaded nylon lines!!
Lcurious - that seems like one of those stories I should check out on Snopes.com - there was a contest in Taiwan where two men lost their left arms when a 5 cm nylon rope snapped by springing back on them, resulting in them losing their left arms, subsequently re-attached successfully with micro-surgery. The number of people was 1600 and the rope was rated at 26,000 kg - the estimated force on the line was 80,000 kg! The Guiness World Records book shows the largest rope being pulled in a festival in Naha, Okinawa, by 15,000 people. The rope is made of rice straw and weighs more than 39 long tons (1 long ton = 2240 lbs), having a diameter in excess of 1.5 meters! It is pulled using separate lines attached along its length to bring about a good harvest to the winning team. I wonder what other records exist concerning ropes?
SR
SR,
Good observation. My own boat does not have the luxury of a windlass and I wasn’t thinking of that. I think that they were talking about the situation where in preparation for a storm, the sailor finds a “safe” mooring place and does not intend to stay on the vessel.
Lcurious,
Just think of the result if they had used Manila Or some of that cheap poly pro stuff - not only burns but slivers. Which is why sailors usually wear gloves.
Larry
Sadly there were some elementary children who lost some fingers during a tug a war line break, I think it was in Dunedin, FL many years ago. They had the whole school participating. I remember reading about it or hearing it on the news. Really sad.