Tendon UJ use by date

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Smidge
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Tendon UJ use by date

Post by Smidge » Sun Nov 24, 2019 7:29 am

I broke a UJ the other day. Probably only been used 15x or less (wifes kit) but over 5 years. Unifiber HD. Sheared straight through centre, not by the bolts. I checked thoroughly before i went out - all i noted was it felt stiffer than I remembered, i put that down to the cold. After 2 slightly overpowered runs, no jumps, no falls, i came in to change down, when i picked up board and rig to carry back to the water the UJ literally fell apart!

To continue my session, as i was in harbour and safe, i had to revert to a 21 year old Boge (also lightly used but must have been out 100s of times) that i only keep for using with the beginner board in non planing winds. Still worked perfectly despite some fairly aggressive use!

Lesson I have learned is that tendon UJs deteriorate with time not just use and inspection is almost pointless- just replace every year or two regardless.
Last edited by Smidge on Sun Nov 24, 2019 10:31 am, edited 1 time in total.

James.blonde
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Re: Tendon UJ use by date

Post by James.blonde » Sun Nov 24, 2019 9:34 am

I have always used boge, but replaced every 3 years as an aim but probably nearer 4 years. The penalty for a breakage could be catastrophic not just for my kit :o

Smidge
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Re: Tendon UJ use by date

Post by Smidge » Sun Nov 24, 2019 10:37 am

To be fair to unifiber, their robust safety rope arrangement using formuline, similar to chinook, would have got me home albeit with some deck damage. I use tendons with a one piece pin and top cup (chinook and unifiber pro hd) because i have previously snapped the thread that the pin screws onto - and no safety rope to help you then..... So i much prefer the single piece top pin and cup arrangement as at least you have a robust rope back up if the tendon goes and no hidden thread to rely on.

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BTB
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Re: Tendon UJ use by date

Post by BTB » Sun Nov 24, 2019 12:17 pm

I’ve never broke a uj. Used bogue and tendon types, I have most I have ever had in the spares bin and all look usable!

I have had a pin unscrew!!!! I will only use one piece now?

TOTD
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Re: Tendon UJ use by date

Post by TOTD » Sun Nov 24, 2019 3:47 pm

OP, is a nice review, with a very reasonable observation.
As a precaution, or think as maintence every 2 years would be a good time frame.
FWIW , I have never broken one. I have one that I use on a junk board in my yard with a junk sail to practice with, it has sit in the sun for prob near 10years, bent over , sail attached, still going fine. Elevation is 6250 , the sun degrades everything .
It’s a Windsurf HAWAII, single bolt tendon.
K4 4Boards Tri Sails,and Chocolate Chip cookies
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Richarli
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Re: Tendon UJ use by date

Post by Richarli » Sun Nov 24, 2019 9:23 pm

My local school who hire out 100's of boards reckon 100 hours of hard use is the reliable life of a tendon joint. They have the data, why would anyone argue?

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FKPhil
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Re: Tendon UJ use by date

Post by FKPhil » Sun Nov 24, 2019 9:26 pm

I’ve broken several over the years and now try and replace them every year(ish).
Only once did it give me an issue on the water but I got home OK with some deck damage.

Once I broke one and replaced it with a spare at the beach… and the new one broke as I was carrying my kit back down to the water! So manufacture quality must also be a factor.
Smidge wrote:
Sun Nov 24, 2019 7:29 am
- all i noted was it felt stiffer than I remembered, i put that down to the cold.
I just replaced one earlier after >1 year of hard use and new/old felt of equal stiffness.

Smidge wrote:
Sun Nov 24, 2019 7:29 am
Lesson I have learned is that tendon UJs deteriorate with time not just use and inspection is almost pointless- just replace every year or two regardless.
yes.

I also carry a spare…
DSC00416.JPG
If you do that screw the fixing nut well on or it works itself off and gets lost

Ruaraidh_K257
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Re: Tendon UJ use by date

Post by Ruaraidh_K257 » Sun Nov 24, 2019 11:36 pm

Crikey.

A good scare story: a friend of mine was competing in the Aloha Classic - he lives in Maui so sails hookipa almost daily - and was using a Chinook base he’d had for a good while...it snapped when he was holding his kit while getting washed around in the whitewater, and he lost his entire rig. They searched the reef and the rocks and the surrounding reefs on the first flat day after that and couldn’t find a trace of it.

He managed to cling onto the board but the brand new carbon mast, £800 boom, 2020 sail, extension and the top half of the base disappeared...

Always replace your tendons no matter what!!!
16, Scottish wavesailor, sponsored by - Neil Pryde, JP Australia, K4Fins, Wild Diamond Tiree

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Gorgesailor
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Re: Tendon UJ use by date

Post by Gorgesailor » Tue Nov 26, 2019 1:46 am

What happened to the safety rope?

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