Harness hook broke during kiteloop

[metrox]

Unfortunetly everything in kite boarding has a finite life. I change my lines every year on my ozone bar, And now changing
my flag out line every year after having it snap where it is knotted at the top of the PU line. Thankfuly it snapped as i was going up and snapped at 3 meters up. Hooks are no different especially if your regularly doing kite loops/mega loops. Im sure crack testing would most likely pick this up.

Metal fatigue is the technical term you're looking for. It's different than rope wear, plastic or fabric. If designed with appropriate materials and safety factor there's no way that these things should be blowing up in a year. They're either trying to save weight, money on materials, or quality and skimping on safety factor. Probably they're designing them to last as long as the webbing that supports the spreader bars. Would have to ask the tech support guys. I'd like a bulletproof spreader bar personally- webbing that is dying is easy to spot. Metal fatigue can be tricky, which is why NDT techs get paid boatloads of money.

Note on metal fatigue: when you stress metal beyond a certain point, fatigue cracks (microscopic) start to form and over time get larger until the material fails. If you never reach this level of stress due to appropriate design/strength, no fatigue cracks, metal doesn't fail . Which is why people still drive cars from 100 yrs ago and people still shoot guns in use since 1911. A properly designed and maintained (no corrosion) spreader bar should be able to outlive you.

Completely agree here ... With proper material strength fatigue not an issue

[Hugh2]

Good topic. I’ve broken two hooks, both on older DaKine harnesses, and when I checked my waist harness there is a spot of rust, barely visible, on one of the welds. But I only use a waist harness for foiling, so no problem.

Checked my daughter’s Ion seat harness and you can’t even easily check it, but she rides so seldom and gently, not worried about it.

When I bought my new Mystic seat harness last year I made sure I could see the welds easily and they look really good to me.

[Herman]

Mse thanks for designing and developing the dynabar I have had many years of trouble free use from mine.

For budding NDT techs you could look into dye penetrant tests as it is relatively cheap. Basically spray on a good wetting dye on and wipe off. Dye penetrates crack. Talc area and dye leeches out revealing cracks.

[Kamikuza]

Hi, I designed the dynabar some years ago avoiding welded parts. If the hook is made of aluminium then it's explained why it brakes. If stainless steel, the heat needed to weld the hook modifies the metal structure making it easy to break.
To avoid this issue I used nuts to fix the hook, i suggest Mystic to do the same. However, i'm surprised this known problem is still there after 20 years the kitesurfig was born.

Thank you! The problem with the Dynabar is that even I can't destroy it...!

I am in need of a new spreader bar pad though...

[Kamikuza]

I've had three of the old Dakine Hammerhead spreader bars snap on me -- one completely, and two broke just one side so I made it back to shore. I think the last one was 2012...?

Always carried a spare, but haven't needed one since. Harnesses wear out before the spreader bar does.

[Kamikuza]

And now changing my flag out line every year after having it snap where it is knotted at the top of the PU line. Thankfully it snapped as i was going up and snapped at 3 meters up.

I'm "glad" I'm not the only one that happens to. Times mine snapped it was less than 6 months old I'd changed my "jumping" bar to mini-5th now...

[metrox]

And here I am back again ... Stiffened hook broke again after 1.5 years ... Well, I am 65kg guy ... 100kg guys should be more aware 100% (if boosting and looping especially).
So conclusion - stiffening plate just a quick solution only.

[Herman]

Me thinks you might not be the average 65kg guy. Looks like a fatigue crack was developing in both of the cylindrical bars, smooth polished area. Then the bars broke and subsequently broke the plate at the weld. To me the stiffening plate is just making sure load is transferred more evenly to both bars rather than adding much strength in itself. Doubt if the alloy used has a fatigue limit, ie a load where even infinite number of cycles does not result in fatigue cracks. You need an NDT engineer or a regular hook change.

All above is just guess work from a photo of course!! Brings new meaning to unhooking. I regularly get through rope sliders but they are easy to inspect and cheap to change before breakage.

How often do you get through a chickenloop??

[metrox]

Me thinks you might not be the average 65kg guy.

Heh, what do you mean?

How often do you get through a chickenloop??

Not understand what you ask about chickenloop?

[keegster17]

Not just Mystic, Ion as well, one of our local kiters had there Ion boardshorts hook break. This is pretty scary stuff, I understand stuff breaks, but this is concerning, especially out far on the water or in a large jump. I have had chicken loop disconnect many times, that is a bit of a scary site on its own.