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 Post subject: Re: TI FWD XBAR FAILURE
PostPosted: Wed May 23, 2012 3:13 pm 
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Location: Kailua 96734
As I recall, that loose mast pin problem has been around for awhile with the AI's too. Always good to inspect it prior to mast penetration.

BTW, we had a TI Xbar failure out here just last week.

Thanks to Stringy, SunE and everyone who is raising awareness and providing feedback.


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 Post subject: Re: TI FWD XBAR FAILURE
PostPosted: Wed May 23, 2012 11:02 pm 
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Location: Central Coast NSW Australia
I gave the replaced TI x-bar a thorough inspection with a magnifying lens and took some macro shots. I'm pleased to report that with over a year of use the welds look OK with no visible cracking. So it seems the initial cracks may well have been from a welding/production issue. This is not the reinforced x-bar.
Image
Image

By way of comparison this is the x-bar from my 09 AI.
Image


I did notice that the socket screw had backed out a little. I didn't take a pic before I'd tightened it but there was a gap between the two nuts of a bit more than a full turn. It seems the socket screw is backing out of the molded in brass hull fitting even with the extra lock nut. I didn't use locktite on this screw as I was concerned it would make removal very difficult if I had another breakage. The good news is that the newer material socket screw is holding up well. I removed it and it was still straight. This is an area that needs regular inspection for looseness. The crossbar bolts/ V-Brace nuts were all still tight. :)
Image


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 Post subject: Re: TI FWD XBAR FAILURE
PostPosted: Wed May 23, 2012 11:47 pm 
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Location: Kailua 96734
That sure looks like Aluminum oxide corrosion starting under the corners...

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 Post subject: Re: TI FWD XBAR FAILURE
PostPosted: Thu May 24, 2012 2:40 am 
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NOHUHU wrote:
As I recall, that loose mast pin problem has been around for awhile with the AI's too. Always good to inspect it prior to mast penetration.

BTW, we had a TI Xbar failure out here just last week.

Thanks to Stringy, SunE and everyone who is raising awareness and providing feedback.

Re: "Xbar failure" - Was that on a AI or a TI? and would you happen to know what year boat it was?

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Ezra Appel
Palm City, Florida
2014 Tandem Island


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 Post subject: Re: TI FWD XBAR FAILURE
PostPosted: Thu May 24, 2012 3:04 am 
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NOHUHU wrote:
That sure looks like Aluminum oxide corrosion starting under the corners...

I agree but I'm not sure that AL oxide corrosion alone would be a contributing factor to a crack developing :?:. So far, the "grey line" around the weld is the only visual indication we've seen so far that proceeded the weld breaking.
This is going to be difficult to diagnose. I wish we could do more than this :? .

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Ezra Appel
Palm City, Florida
2014 Tandem Island


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 Post subject: Re: TI FWD XBAR FAILURE
PostPosted: Thu May 24, 2012 3:18 am 
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stringy wrote:
I gave the replaced TI x-bar a thorough inspection with a magnifying lens and took some macro shots. I'm pleased to report that with over a year of use the welds look OK with no visible cracking. So it seems the initial cracks may well have been from a welding/production issue. This is not the reinforced x-bar.

By way of comparison this is the x-bar from my 09 AI.

I did notice that the socket screw had backed out a little. I didn't take a pic before I'd tightened it but there was a gap between the two nuts of a bit more than a full turn. It seems the socket screw is backing out of the molded in brass hull fitting even with the extra lock nut. I didn't use locktite on this screw as I was concerned it would make removal very difficult if I had another breakage. The good news is that the newer material socket screw is holding up well. I removed it and it was still straight. This is an area that needs regular inspection for looseness. The crossbar bolts/ V-Brace nuts were all still tight. :)

Stringy, excellent photos and reporting!

Re: - "I gave the replaced TI x-bar a thorough inspection with a magnifying lens.... welds look OK with no visible cracking."
Well that's good to hear :wink:.

As far as I know there have been no reports of this happening on a AI.

Re: - Screw Socket. Thanks for reminding me to check mine. I installed mine with blue loc-tite in the brass insert and then a double nut on top a while ago. I'll let you know what I find by comparison.

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Ezra Appel
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2014 Tandem Island


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 Post subject: Re: TI FWD XBAR FAILURE
PostPosted: Thu May 24, 2012 5:12 am 
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Location: Cape Coral, FL
sun E sailor wrote:
kayakman7 wrote:
You guys had me concerned that I was neglectful about maintaining my boat... So I checked all the nuts, bolts, and screws and found that everything was indeed still tight. Which means, at least to me, that I broke it by sailing it.

I'm just wondering exactly which conditions were to much...

Also, does the old x bar get returned to hobie? If not, I might make a TI3. All I would need are the clamps that hold the x bar down.

Cheers,
J

kayakman7
If everything was tight that's good to know.

At this point I don't believe we have a definitive explanation as to what exactly causes the weld on the bearing plate to break. Hobie has since corrected this problem with their new design and that's what is most important.

What I've been trying to establish is how the average person can determine beforehand, if their old style crossbar is about to fail. I should think Hobie would be interested to have your crossbar to see if this "grey line" is actually a crack in the weld or not.

However, you did not break it by sailing it; it broke because somethings wrong, it's not your fault. As for "which conditions are too much..." I believe the general rule of thumb is when one begins to see the whole ama a couple of inches under water. It's also been well discussed about the benefit of when to reef your sail. Again, I wish for all of us to be as safe as possible on the water and proactive through these continuing discussions.


If I had a thin enough feeler gauge, I could push it though the crack. The camera I used isn't high enough quality to show it but there is definitely a crack.

The physics of the x bar suggest to me that there is some deflection of the bearing ring, that repeated high loads stress these welds and they begin to fail where the load is the highest, at the edges.

The new x bar design is much stronger, likely many times stronger, because it has a much longer lever arm with which it distributes the load over.

Welds generally fail for two reasons; most likely is poor craftsmanship, less common but what is likely happening here, is when the metal is welded, it's crystalline structure changes slightly and becomes less able to deal with flexing. After thousands of flexing cycles, the metal begins to fail, progressively getting weaker, and at an increasing rate, till it fails completely. It could even be hundreds of thousands or millions of cycles, but every second we sail, every wave we hit, every minute change in wind, is another cycle on that weld, another step towards it's failure.

Just my humble opinion but....

Cheers,

J

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 Post subject: Re: TI FWD XBAR FAILURE
PostPosted: Thu May 24, 2012 6:46 am 
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J,

Thank you for this additional information, it is very helpful. I understand now exactly what you are saying.

You're input and knowledge is greatly appreciated. The more we can continue this dialogue, the more we will discover about what causes this problem and ultimately, what people can do to be proactive about it.

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Ezra Appel
Palm City, Florida
2014 Tandem Island


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 Post subject: Re: TI FWD XBAR FAILURE
PostPosted: Thu May 24, 2012 6:49 am 
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Location: Palm City, Florida
Stringy,
Yeah, I checked the two locking nuts on my screw socket this morning and I was able to tighten it up a bit more. Thanks again :wink:.

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Ezra Appel
Palm City, Florida
2014 Tandem Island


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 Post subject: Re: TI FWD XBAR FAILURE
PostPosted: Thu May 24, 2012 1:43 pm 
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Sun E,

the failed XBAR was on a 1 yr old TI. Owner heard few noises, thought the clearance on the bearing ring seemed odd and later discovered some looseness in the XBAR collars.


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 Post subject: Re: TI FWD XBAR FAILURE
PostPosted: Thu May 24, 2012 1:51 pm 
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kayakman7 wrote:
the metal begins to fail, progressively getting weaker, and at an increasing rate, till it fails completely.,.. every second we sail, every wave we hit, every minute change in wind, is another cycle on that weld, another step towards it's failure.
Cheers, J
Cheers?!? :lol:

That corks it. I'm gonna put this AI sukka on E-Bay!


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 Post subject: Re: TI FWD XBAR FAILURE
PostPosted: Thu May 24, 2012 3:21 pm 
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NOHUHU wrote:
Sun E,

the failed XBAR was on a 1 yr old TI. Owner heard few noises, thought the clearance on the bearing ring seemed odd and later discovered some looseness in the XBAR collars.

Hummmm...?
Loose Xbar collars goes back to what Matt was saying.
Happening to a 2011 TI is not good.

Not quite sure what you mean by "clearance on the bearing ring seemed odd". That could have been the mast collar itself sliding up on the mast and needing to be re glued. I had to do this to mine recently.

It's probably going to end up being a combination of several factors that puts more strain on the weld than it was originally designed to handle. If there was also a manufacturing problem that is not easily recognized, then you can understand the frustration people must be feeling who have the original crossbar in terms of what to do :?: .

Cheers :roll:

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Ezra Appel
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2014 Tandem Island


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 Post subject: Re: TI FWD XBAR FAILURE
PostPosted: Thu May 24, 2012 3:27 pm 
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NOHUHU wrote:
kayakman7 wrote:
the metal begins to fail, progressively getting weaker, and at an increasing rate, till it fails completely.,.. every second we sail, every wave we hit, every minute change in wind, is another cycle on that weld, another step towards it's failure.
Cheers, J
Cheers?!? :lol:

That corks it. I'm gonna put this AI sukka on E-Bay!


And if you believe NOHUHU would sell his AI, I have 2,000 acre's of good bottom land to sell you great farm land, just south of Key West, Florida. :lol:

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 Post subject: Re: TI FWD XBAR FAILURE
PostPosted: Thu May 24, 2012 3:38 pm 
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I hear aquaculture is the growing thing :D

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 Post subject: Re: TI FWD XBAR FAILURE
PostPosted: Mon May 28, 2012 8:24 pm 
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Looks like I am the next victim for a soon to be weld failure. After being alerted by sEs of the problem, I check my welds and found these stress cracks. Decided that my weekend fishing trip 6 miles offshore had to be put on hold till I knew that my boat won't fall apart! Hopefully, Hobie can get it to me the part by next weekend! Thanks for all the post on this topic, and thanks to sEs for alerting me to the problem.
Image

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