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Old 08-03-2019, 17:13   #76
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Re: Near Disaster. Whos to blame?

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Originally Posted by MEC View Post
I agree with Beetle's recommendation that the shroud mast connector should utilize a T fitting. The existing connector places the fastener in tension and bending, neither of which a rivet is suitable to operate with the reliability that this connector must have. Blind rivets are suitable for shear loads. In this application the designer may have specified aluminum rivets to avoid galvanic corrosion that use of SS or Monel rivets would create. This is a moot point because the connector design relying on rivets to withstand large and fluctuating tensile and bending moment loads is the issue.


Personally I would never accept an aluminum fabricated clevis connector in this application since the weld will be subjected to bending and tensile loads, aluminum welds have no endurance fatigue limit, so its only a question when the weld will fail not if.



Based on what you have for cap shroud connectors, I would be wondering if the mast and rigging system had other defects. For example the plastic bushing between the threaded nut and mast wall will not have a long service life exposed to UV and weather. Does this fastener have an internal compression tube? If the answer to the question whether there are other low reliable components to the mast assembly, then before you disembark on a blue water cruise or subject the boat to heavy weather conditions, I would pull the mast and all rigging and have the hardware properly engineered and re-worked to be reliable for blue water all oceans sailing yacht.


The argument that other Leopard catamarans have sailed with (assumed) similar cap shroud connector design is an example of the "normalization of deviance". Do not be persuaded by such argumentation that, hypothetically, since another Leopard yacht didn't experience disaster from this connection joint failure (don't know this is true), that you won't experience disaster using these unacceptable rigging connections.



It may also be prudent to engage a naval engineer having experience in catamaran design and construction to inspect the forward cross beam, determine why the original beam failed and that the replacement will have mitigated the failure mode.


I hope this information is useful.

Not sure I would agree with all of this. The Leopard's, particularly of this vintage and before, are known as very tough boats. Capable of much long distance sailing, and they have proved it. For years and years, they delivered almost all of them, all over the world, on their own bottoms, in good seasons and bad. In these deliveries, they did at least 4 million miles without major mishap. Most worked, hard, and in many cases for many years, in the charter industry, which is not easy. In the Caribbean, there is constant wind, and in delivery trips between island groups, sometimes some pretty brisk seas. Many have been retired to private use, and many of these have also done a lot of serious cruising, including circumnavigations. How do I know this? Well, I have owned a 1999 L45 since 2004. I work her in charter in the Caribbean, and have done some rough offshore trips up to the Chesapeake, as well. She sailed from South Africa. She has been through winds over 50 knots, under sail. Her mast stayed up through Irma, even though debris hit one of the lower spreaders, forcing it through the mast wall! (But don't worry, I replaced it as I am a believer in keeping things in top condition.) There are two very active owners groups online and I am a member of both and very active on one. A good many of the other owners are also marine industry professionals. Are the Leopards perfect? Of course not! There are even a small number of chronic problems. But none, repeat none, are associated with the rigs, i.e. the mast, boom, crossbeam, etc. A couple of 44's did lose their masts a few years back, but otherwise, the Leopard masts are not in the habit of giving problems.



Their are a number of welds on the rigs. My rig was built with T-ball fittings on the lowers and the diamonds, and the welded tang on the uppers and the forestay and crossbeam. I don't know if the tangs go through the spars, but I am pretty sure the crossbeam attachment for the headstay does. Some variation of this is present in all the Leopard rigs, although the double spreader rigs have given way to single spreader ones. I respect that you have a point of view, and that your presentation sounds very professional, but these are very heavy welds, with much surface area, and they are very well done, and the actual evidence is that they last a long, long time. The designer, Alex Simonis, is very well thought of in the water sailing">blue water sailing world. The mast builder, Sparcraft South Africa, likewise.


To imply that these rigs are inherently dangerous, poorly designed or built, is irresponsible and inaccurate. I have no association with any of the companies, but it always infuriates me when idle discussion, virtually no better than bar stool discussion, winds up manufacturing a rumor that such and such is flawed, when the commentator(s) have no personal experience with the item in question. The actual experience of Leopard owners, over more than twenty years, gives credence to the demonstrable FACT that the rigs and boats are strong and overbuilt, if anything. And theorizing counter to the empirical facts is not doing anyone any favors!


The question is not with the original design, but with what happened to this particular mast, what damage occurred, and how it was "fixed". We don't even know how it came to grief, if it's original, or if there is a connector between the two plates, yet! Let's see what we learn from Sparcraft, when they get their hands on this rig. I bet it is interesting! Let's see if the broker has anything to say for themselves....they will certainly know that their reputation has been justifiably, it seems, thrown into disrepute. Same thing for the surveyor.



Obviously, there are some villains in all of this, and let's just see where it goes. But, I can tell you that the masts that Robertson and Caine send out the door are well designed and built for tough use. That fact has been proven, hundreds of times over.
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Old 08-03-2019, 18:06   #77
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Re: Near Disaster. Whos to blame?

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Originally Posted by contrail View Post
.......

Their are a number of welds on the rigs. My rig was built with T-ball fittings on the lowers and the diamonds, and the welded tang on the uppers and the forestay and crossbeam. I don't know if the tangs go through the spars, but I am pretty sure the crossbeam attachment for the headstay does. Some variation of this is present in all the Leopard rigs, although the double spreader rigs have given way to single spreader ones. I respect that you have a point of view, and that your presentation sounds very professional, but these are very heavy welds, with much surface area, and they are very well done, and the actual evidence is that they last a long, long time. The designer, Alex Simonis, is very well thought of in the blue water sailing world. The mast builder, Sparcraft South Africa, likewise.
Question? Are your welded tangs on the uppers welded to the mast or welded to plates that are then pop riveted to the mast? Any photos of the 'as built' set-up?
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Old 08-03-2019, 18:16   #78
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Re: Near Disaster. Whos to blame?

Considering the apparent inadequacy of this rig and Leoard's generally good record of service for their rigs, and the spotty history regarding this rig... I think it reasonable to think that this was a mast salvaged from another damaged boat and not the original spar.

The facts don't add up well! And it will be interesting to hear what the spar builder says.

Jim
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Old 10-03-2019, 03:30   #79
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Re: Near Disaster. Whos to blame?

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Rob
You are probably right, but if this is the way most Leopard 46s are rigged (ie rivited with the right rivets), then they have enough long distance miles on them to be proven adequate.
Just because most Leopards have load bearing tangs fastend like that doesn't make it right.
T terminals is the correct and structually sound way to go.

I have seen a lot of this sort of problems during during my 30 odd years of boat building.
After all considering the cost of these contraptions ...
By the way, in my time I rarely had much luck with surveyors..the last one i employed had a pair of binoculars to inspect the mast and its fittings. Had to send him home and got another one...this one actually went up the mast. hmmmm
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Old 10-03-2019, 22:29   #80
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Re: Near Disaster. Whos to blame?

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Originally Posted by Icarus View Post
Just because most Leopards have load bearing tangs fastend like that doesn't make it right.
T terminals is the correct and structually sound way to go.

I have seen a lot of this sort of problems during during my 30 odd years of boat building.
After all considering the cost of these contraptions ...
By the way, in my time I rarely had much luck with surveyors..the last one i employed had a pair of binoculars to inspect the mast and its fittings. Had to send him home and got another one...this one actually went up the mast. hmmmm
I'm not saying it is the best way to create a rig, just that if you have boat that is both popular and does many long distance passage miles over many years and the rigs do not fail -- then yes it is adequately engineered for tbe purpose.
There have been many t-ball connection failures over the years, so nothing is magic.
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Old 14-03-2019, 18:56   #81
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Re: Near Disaster. Whos to blame?

I suspect thumbs up is right, ex cyclone boat
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Old 14-03-2019, 22:28   #82
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Re: Near Disaster. Whos to blame?

So, did I miss seeing it? Are Leopard 46s normally rigged with riveted spreader bases or not? Seems an important thing to determine at this point.

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Old 15-03-2019, 05:23   #83
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Re: Near Disaster. Whos to blame?

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Originally Posted by Jim Cate View Post
So, did I miss seeing it? Are Leopard 46s normally rigged with riveted spreader bases or not? Seems an important thing to determine at this point.

Jim
I just looked through some yachtworld ads, and no, this doesn't appear to be how their spars are manufactured. I'd be very pissed, too.
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