I am new to cat sailing and I had my first dis-masting today. I thought my windward shroud cable snapped, but after getting on dry land and inspecting the boat, it appears that the cable slipped out of the marine eye (the fitting that the cable is crimped into and pinned into the chainplate). First off, I can't believe that cables capable of handling such loads are secured by a crimper. Secondly, I have heard tales of cat sailors who rig a backup for their shroud that would have prevented the mishap that cut my day short. Is there anyone out there that can feed me any information on either of these topics?
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Barry Jones
1982 NACRA 5.8
Space Coast, Florida
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shroud back-up rig
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Posted: Jul 03, 2011 - 07:53 PM
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Posted: Jul 03, 2011 - 08:38 PM
Sounds like someone didn't make up your shrouds correctly. Nicopress swages when done properly fuse with the wire. The wires gets embedded so well into the metal that they become one, and they are much stronger than the wire itself. It is a serious operation that requires a special crimping tool or hydraulic press but. That being said most people who make thier own rigging double swage thier standing rigging (use 2 crimps instead of 1).
Profesionally made rigging almost universally uses hydrualically swaged fittings which are even stronger than the normal swages and much cleaner. If you had nicopress fittings on the bottom of your shrouds chances are it was a poorly made homemade shroud by someone who didn't know how to do it or it is 30+ years old. That is a wakeup call for you to replace your all your wire rigging with brand new just for safety if nothing else.
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Dave Bonin
1981 Nacra 5.2 "Lucile"
1986 Nacra 5.7 "Belle"
Winnipeg, Manitoba, Canada
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Posted: Jul 04, 2011 - 06:02 AM
The marine eye is a hydraulically swaged fitting, stronger than nico press/thimble. The rigger I use said they are done in a 20,000lb press.
As Dave said, they are very strong, very few people,(none that I know) use a back up. In essence what happens is the walls of the marine eye are pressed so tightly into the cable that they deform,into the strands of wire. If you look closely at the wire you will see that it is spiral wound, sort of like really coarse threads on a bolt. Once the marine eye gets formed into these "threads" the only way for it to come apart is to break the wire, break the eye, or shear off all the "threads" that are now formed inside the barrel of the fitting. The eye is stainless steel of a quality that exhibits high resistance to shear loads, making it very strong.
The only way to provide redundancy would be to run an entire second set of shrouds to a second set of chainplates in the hull, & a second masthound. Murphys Law says that if you added a short length of wire from just above the eye to another hole/pin on the chainplate, it would fail up at the hound, or the chainplate would pull out of the boat.
Replace them all if old, any broken strands, or even kinks, then sail. I run a backup for my forestay, but only because the connection is line, (via a Portuguese turnbuckle). I have mostly inexperienced crew helping me, & the second line is to tension/detension the rig, the first is taped to prevent inadvertent release.
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Posted: Jul 04, 2011 - 09:45 AM
Thanks for the insight. I just bought the boat (1982 Nacra 5.8) so I don't know where the shrouds came from. It is a sure bet that they are not the original equipment. I feel better about the hydraulic swagging process. I found a N5.8 SHROUD 5\32" BLACK ROLLER SWAGED" on the murrays.com web site for $68 each. The description says that they are "hydraulically swagged to be clean and strong and constructed to factory specifications". I am putting in an order for a pair today.
Thanks for passing on your wisdom to a newbie.
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Barry Jones
1982 NACRA 5.8
Space Coast, Florida
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Posted: Jul 04, 2011 - 11:22 AM
Measure your old shroud, from pull to pull, there is probably a diagram somewhere on Murrays that shows a pictorial of pull to pull, then order two of them. Something else might have been modified, & the standard shroud may not be the best fit.
You may also want to inspect your forestay, & order one of those too if it is the same age as the shrouds. If it lets go you lose the mast. Think a bit about future considerations, if you want to add roller furling, you need a shorter forestay. The ends of the stay can be thimbles or eyes, it all depends on what is on the end of the bridle wires, & what you want to do as the end result.
Enjoy your boat, I had my old 5.7 up to 21 mph yesterday.
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Hobie 18 Magnum
Dart 15
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Nacra 5.7
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Bombardier Invitation (Now officially DEAD)
Various other Dock cluttering WaterCrap
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Posted: Jul 04, 2011 - 11:23 AM
Sorry to sort of thread jack, but does anyone have shrouds from Saltydogmarine.com ? One end is double nicro pressed and the other is roller swaged.
The price difference between saltydog and murrays is like $20 per shroud for my boat and a $40 savings is very enticing... $48 vs $70 ea
Edited by matt922 on Jul 04, 2011 - 11:34 AM. -
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Posted: Jul 04, 2011 - 11:58 AM
Edchris177, I will measure the shrouds to make sure I don't get any surprises. I already have roller furling and the cables look pretty new. Of course, the shroud that failed on me yesterday looked good, too.
I was doing 18+ yesterday, when I heard a loud "snap" and the mast came tumbling down. I hope to be back on the water nest weekend.
According to Edchris177, hydraulically swagged is better than nicro pressed. Believe me, the time I spent rescuing my boat yesterday was well in excess of a $40 savings.
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Barry Jones
1982 NACRA 5.8
Space Coast, Florida
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Posted: Jul 04, 2011 - 12:06 PM
A nicopress done with a hydraulic press or a roller swaged fitting are about the same in strength. The roller swaged fittings are cleaner. Even the hand pressed nicopresses are plenty stong if they are done correctly.
You will probably find that the bottom of the shrouds from Murray's are roller swaged and the tops are doubled nicopress fittings (one above the other). I think that is what mine are... The nicopress gives you a nice large eye to shackle to at the top and the roller swage gives you a clean edge free treatment at the bottom and a nice pin hole. I know for sure that I had my forestay custom made and it is like that.
Regards,
Dave
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Dave Bonin
1981 Nacra 5.2 "Lucile"
1986 Nacra 5.7 "Belle"
Winnipeg, Manitoba, Canada
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Posted: Jul 04, 2011 - 12:28 PM
While i agree, the single nicro pressed shrouds i currently have, have held on fine. Only replacing because i had one of "those" days. The wear (stretch) is starting to show at the thimble. My shrouds have thimbles at both ends, which i kinda like because it makes em easier to pin every time i take the boat out. -
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Posted: Jul 04, 2011 - 03:42 PM
Barry,
Do yourself a favor. Buy all new rigging, and buy quality. Make sure to get the diamond wires and forestay bridals also. I've preached this before. Replace all your rigging on a schedule, all together. You were lucky. A lot of rig failures turn out to be a lot less fortunate. I know, I got the t-shirt.
FWIW, hydraulic swages into marine eyes fail all the time, due to corrosion. You can not see it, there is no warning. It's rather foolish to to take your boat out if you don't know the age of your standing rigging.
Edited by mummp on Jul 04, 2011 - 05:02 PM.
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Philip
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Posted: Jul 04, 2011 - 07:54 PM
Thanks for the advice. I am going to replace all of the standing rigging. Any recommendations on how often the rigging should be replaced?
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Barry Jones
1982 NACRA 5.8
Space Coast, Florida
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Posted: Jul 04, 2011 - 08:06 PM
Regardless of what fitting you choose, it is likely you won't notice much before they fail. Sometimes you will see some corrosion next to the fitting or a few strands breaking.
Like Mummp says the only real way to do it is to replace the rigging on a schedule and don't trust rigging that you don't know the age and history of. New rigging isn't all that expensive given the cost of the rest of the parts on the boat. And MUCH cheaper if you consider the cost of a noggin if the mast falls on you. I've accidentally dropped the mast once (my own error not the rigging), and I would NOT have wanted to be anywhere near where that mast fell!!!
Most people on here recommend every 5 years to replace the wire standing rigging. Maybe even sooner if you are in salt water and sail alot (or race), maybe a little longer if you are like me and only sail 2-3 hours a week for 3 months, store the boat mast up all year, and only sail in fresh water. Lots of people have sailed on 10+ year old rigging (myself included) but really they are playing with fire by doing so. It might hold up or it might not, again the consequences way outweigh the cost!!
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Dave Bonin
1981 Nacra 5.2 "Lucile"
1986 Nacra 5.7 "Belle"
Winnipeg, Manitoba, Canada
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Posted: Jul 05, 2011 - 09:31 AM
Don't get hung up on nico press at one end, eye on the other. In many cases the nico pressed thimble on one end is to facilitate connection of 3 wires up at the mast hound. For the lower connections, the eye or fork are cleaner, but they do cost more.
Philip is right, the failure is generally due to what is known as crevice corrosion, especially in a saltwater enviroment. It happens at nearly a microscopic level, within the confines of the fitting, & you may not see anything unusual.
Edited by Edchris177 on Jul 05, 2011 - 09:36 AM.
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Hobie 18 Magnum
Dart 15
Mystere 6.0XL Sold Was a handful solo
Nacra 5.7
Nacra 5.0
Bombardier Invitation (Now officially DEAD)
Various other Dock cluttering WaterCrap
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