I have several chinook tendon UJs made in 2020. I'd like to use them but am wondering about degradation since they were made. They have been in a ziplock bag all this time. I know I've seen old tendons left in the shed start to distegrate, so I'm wondering whether I can use these ones or should dump them?

Any thoughts?

The main things that degrade rubber and plastic is light and heat. I'm not even sure if it's rubber, probably some kind of polymer.If stored in darkness in the zip lock bag , it should be fine. However , certain rubber will just simply self destruct over time if it doesn't contain staberlizers . I would think that Chinook would use top grade rubber with all the bells and whistles. It should be for the cost of them. Probably 20 cents of material . It is four years now and would make me think about being paranoid. Contact Chinook.

4 years is not too bad ,

I used to keep a tendon in a zip lock bag in my wagon. Broke a uni so put it in. Went out and sailed for a bit. Looked at it and it was split in a few places. Chuck em or keep a very close eye.

^^^^ same here
if it's been warm, pitch it
i had a new one in the bits box in the car and it literally broke in two all by itself after say 2-3yrs

Don't risk it! It's not worth the swim or worse and the tendons are probably even older than that as they might have been sitting on a shelve somewhere before you got them.

About 5 weeks ago I went for a sail - using a brand new tendon that i had in my equipment box from 3 years ago - it snapped within 30 seconds. Not sure where I got it from etc or if it was an online buy but yeah sitting around in a box that was kept in the car probably killed its integrity.

These responses are of course what I didn't want to hear
Mins have been in a ziplock back in the dark inside the house which might mitigate, but I'm not going to use them...

Does the rope around the tendon work ok?

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choco said..
Does the rope around the tendon work ok?

its saved me from swimming two times! Its some stability when the tendon snaps

How do we know how long it was sitting in the shop before you purchased?
I don't think a tendon sitting in a dark spot in the garage would be any different to sitting in a windsurfing shop.
Well I hope not anyway!!

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spanishwog said..
How do we know how long it was sitting in the shop before you purchased?
I don't think a tendon sitting in a dark spot in the garage would be any different to sitting in a windsurfing shop.
Well I hope not anyway!!

Chinook tendons have the manufacturing date on them.

I wouldn't rely on the safety rope, unless maybe it's one of those wide strong fabric things. The rope that most tendons use is really only to prevent the rig from completely separating from your board.

I had to sail back with a snapped tendon and by the time I was back at the beach (only one run), the deck was cracked and needed a professional repair. I have one of those vulcan pads around my mastbase ever since so if it happens again, I might be able to rest the mast on the pad, limiting damage (hopefully). Next time I might swim instead if not too far out though.

Yes, when the tendon breaks, the safety rope will allow you to punch a hole in the deck of your board on the way back from the beach.

My recommendation based on years of hardcore use: Replace annually and source your tendons directly from the manufacturer to assure fresh stock.

I recently replaced my Chinook tendon with my spare that had been in storage in a sandwich bag in a sealed container in a draw inside the house. I rigged my gear connected the based to my board, layed the board down. It then snapped clean through. I went home put my other spare that had also been in storage. Did a test, it too snapped.
I normally replace yearly with fresh ones.
But this year, thought I might put in the spare.
I won't be doing that again.
I've also had that webbing break when the hourglass style one broke while sailing.
Also had as mentioned above the rope save me but the broken tendon punch holes in my board when sailing in.

Hard to know how long they've been sitting in the store/warehouse/factory.

Install it, check it and keep an eye on it. Maybe do a dirt windsurfing or some sail chi first !

I tried the clear ones. It broke after a year, it failed inside the socket where the pin goes thru the hole after a jump.They normally split in the middle. I think the clear ones are a better material that resist UV.

I tried the clear ones. It broke after a year, it failed inside the socket where the pin goes thru the hole after a jump.They normally split in the middle. I think the clear ones are a better material that resist UV.

Chinook has the date stamped on the end, I bought a new one last week and it was stamped 5/23 so already 18 months old

Are you sure that's the manufacturing date and not the expiry/best before date?

In all seriousness, while not surprised that's actually quite terrible right? Hope it has been stored in conditions that preserves the material...

I hope all you guys worry about your vent screw O ,Rings manufacture date . They also deteriorate . It's probably a good idea to buy a few every couple years and change them on all your boards.

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Imax1 said..
I hope all you guys worry about your vent screw O ,Rings manufacture date . They also deteriorate . It's probably a good idea to buy a few every couple years and change them on all your boards.

Viton o-rings should last a long time, but i replace them anually when I replace my tendons. Cheap insurance from the local hardware store plumbing department.

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Imax1 said..
I hope all you guys worry about your vent screw O ,Rings manufacture date . They also deteriorate . It's probably a good idea to buy a few every couple years and change them on all your boards.

A good o-ring is hard to find. I'm using aldi ones at the moment.