I took my son and his friend out on the Nacra 460 today and about 20 minutes into the sail the shroud broke and the mast fell. No one was hurt and it was not long before a trio in a Zodiac gave us a tow in.
The boat is only a few years old and has been sailed less than 15 times. The shroud does not appear to have any corrosion or other damage besides being broken. I am surprised that this failed and I dont think its normal.
I cant seem to find shrouds for sale on line, so should I call the dealer, or look to have something made locally? I've swagged wires, but I not sure I want to take on a shroud. Thoughts?
Here is a picture, let me know what you think:
Edited by tradisrad on Aug 05, 2017 - 09:48 PM.
Interesting that it broke exactly at the end of the swage, I am no expert whatsoever, just wondering if it was work hardening if it flexed at that point.
Is the tang that the swage eye connects to at the correct angle, i.e. it doesn't point away from the mast a little forcing the wire to bend where it exits the swage? Is it stored with the mast up?
Anthony
Did it do any damage to the boat?
I agree that mis alignment would be the prime cause of failure in this region.
Check the diameters of the other fittings to see if this was over compressed.
Important question
What is a few years old?
What year is the boat?
Possibly an error when manufacturing the shroud. Swages have to be done to very exacting tolerances in order to achieve full strength. If the part was over-swaged, it could have damaged the wire. Tooling wear or operator error can cause this.
It's also possible that the wire corroded (particularly if you sail in a salt water environment). The corrosion may not always be visible (stress corrosion cracking). Or, as others have mentioned, if the wire was kinked at the terminal fitting, this would create a stress riser that could lead to failure.
The age of the wire (cyclical loading) could have contributed or perhaps the wire was simply overloaded (you don't mention wire diameter, wind strength, or total crew weight). A lot of things could have caused this.
sm
I believe Murray Sports can replace the shroud, and considering the failure mode here, I would replace both. They built new wire for my 5.7 which had been in service since 1986, so in spite of some salt exposure on your rig, I would not expect this failure on a comparatively new boat.
Give Murrays a call about the wire, and if they don't have the spec already, you can give them measurements from your good shroud and they will build it. Many sail shops also build custom rigging and the N460 should be able to be duplicated.
tominpa wrote: I believe Murray Sports can replace the shroud, and considering the failure mode here, I would replace both. They built new wire for my 5.7 which had been in service since 1986, so in spite of some salt exposure on your rig, I would not expect this failure on a comparatively new boat.
Give Murrays a call about the wire, and if they don't have the spec already, you can give them measurements from your good shroud and they will build it. Many sail shops also build custom rigging and the N460 should be able to be duplicated.
+1
I too have had excellent service on rigging with Murrays. Even on custom lengths they have at times turned my order around same day. I have purchased at least 6 sets of standing rigging from them over the years with absolutely no issues. If one shroud failed I would absolutely recommend replacing both. I would send the unbroken one to Murrays so that the can stretch/measure with their methods and return a perfect fit.
Can't really tell from the photo, but was the wire kinked near the failure? Again hard to tell from the photo, but the dull appearance of the wire at the break points to corrosion and fatigue.
Just my thoughts, respectfully submitted.
The boat is a 2015 model. Sailed 5 time in fresh water by the first owner. I bought it in May (2017) and have sailed it 7 or 8 times in salt water, taking care to rinse thoroughly.
No damage to the hulls, a large scratch through the anodizing on the mast and a few scratches on the cross beam. I'm luck here, but I did put insurance on the boat when I bought it just in case. I wont make a claim on this.
The boat is not stored mast up, but I do leave the rigging attached to the mast and hulls. I dont think the wire was kinked. I inspected them after I bought the boat and saw nothing obvious.
There was 3 of us on the boat, the wind may have been gusting to 18 or 20 MPH.
The wire diameter is 1/8", however the calipers measure it slightly undersized. It may be Metric wire as it measures 2.9mm exactly and the end it's swagged to has 3mm stamped on it. I will have the next ones made with thicker wire.
I should note that the other shroud has one broken strand in the same location. Also, the last time I sailed it I heard a few "pops" coming from the shrouds area, so perhaps it was already failing. I did not check the wire after that sail.... my bad, but really I never would have thought the wires would be breaking. I have a Wave and it makes sounds as I beat the snot out if it, so I thought it was normal for the boats to creak etc.
I sent an email to Nacra USA and I will follow up with a phone call to them tomorrow to see if they will do anything for me. Murray's will be my second plan.
thanks for the replies.
I recently changed shrouds because a few strands were cut at that same point. Before last use it was just one strand, during that sail it turned into three or so, so I took some line and both traps and made additional support to end the day.
Wow, 1/8 seems very thin for shrouds.
The trapeze on my 18 is 1/8 and shrouds are 3/16.
Murrays and salty dog both sell 1/8 for the smaller boats and 5/32 for the bigger ones. 1/8 seems correct for the little nacra
I would suggest you replace with 5/32 diameter shrouds. Murrays offers this as an option for many boats that have stock 1/8" shrouds. There is roughly a 50% strength increase going from 1/8" to 5/32" diameter and the thicker shrouds only cost a few bucks more. The wire size may or may not have been a contributing factor to your particular shroud failure, but either way, bumping up to the next larger size is cheap insurance in my book.
sm
Confidence is key! thicker wires may well equal peace of mind. I'm gonna have to replace all my standing rig soon just to eliminate that as a possible failure mode. (yeah, anything can happen but new wires from a trusted maker should at least be a known quantity). Now if I can keep my bow tangs, and shroud tangs, and mast fittings in one piece....too many bad stories lately! Oh yeah, the dolphin striker too and praying for not too much corrosion on the beam when I do that job.
Edited by tnell on Aug 06, 2017 - 09:22 PM.
Rigging that has touched salt water should be changed every 2 years
(including bridal and diamond wires if you have them)
There was 3 of us on the boat, the wind may have been gusting to 18 or 20 MPH.
The wire diameter is 1/8"
3 people on a 15' boat is a lot (adults or adult + 2 kids?)
1/8" is pretty small - and as mentioned the tolerances for fittings is very "tight"
18-20 knots is a lot of wind = i believe a shroud could pop with a good gust under those factors
tradisrad wrote: I am surprised that this failed
Your kidding?
tradisrad wrote: the other shroud has one broken strand in the same location. Also, the last time I sailed it I heard a few "pops" coming from the shrouds area, so perhaps it was already failing.
Some lessons are learned the hard way. Carry on . . .
I think this failure starts not because of tension but by torsion, twisting or whatever happens (slowly and incrementally) when stepping the mast, dealing with the wires on the trailer, etc. Then if fails because it's not strong enough to hold the tension.
I called Murray's and they, obviously, can make the cables for me. The original cables have the Roll Swage ends on them. After a bit of reading I think I am going to have them make the cables with the Ferrule and Thimble terminations. I will also have them made with the 5/32 wire.
tradisrad wrote: I called Murray's and they, obviously, can make the cables for me. The original cables have the Roll Swage ends on them. After a bit of reading I think I am going to have them make the cables with the Ferrule and Thimble terminations. I will also have them made with the 5/32 wire.
just curious
what in your reading made you switch to thimbles?
MN3, I found a post here on "The Beachcats" and, really, it was your post where you said you gave up on the "airplane fittings". I also read the failure analysis on Practical Sailor and it seems that there is more to the roll swaging to make them work.
After reading that, I wonder why mine failed after a hand full of uses. Perhaps my boat was overloaded, maybe the swaging was not done correctly, perhaps it was corrosion (I dont think so).
Plus it will save me about $20 a cable. I've been bleeding cash this summer and it's got to stop.....
Am I making a mistake by not using the roll swaged ends?
https://www.thebeachcats.com/forums/viewtopic/topic/16638/start/0 ,
I found a post here on "The Beachcats" and, really, it was your post
Oh, i defiantly wouldn't trust that! (jk)
Am I making a mistake by not using the roll swaged ends?
I think your reasons are $ound
I think thimbles will flex more than a fitting, but ... that doesn't bother me
I received the new rigging from Murray's yesterday and it looks great. I installed the bridals and if I can make time to sails this afternoon I will install the rest of it. I went with 5/32 wire and it looks nice and "beefy".
When I reinstalled the bow tangs I used some anti-seize on the screws as they were fairly tough to get them out (I used a large phillips screw driver that has a hex shank and I put a wrench on the shank to get the torque I need to loosen the screws). I don't think this is an issue, but if it is please speak up.
you can tap and die them if you want to make them run clean and smooth again
I use tef-gel for anti-seize