At what point do you replace your UJ tendon? I've been on the original one for about three seasons now. I don't get out a ton, and I spent most of last summer on a wing ding, so my UJ didn't get any use until September of last year, and then it was probably only out 8 times or so. Are there "things to look for"? Or do you just replace it after a season or two? Or three?

There's some evidence that they just plain age even without use, especially if they've been subjected to extremes of heat or cold. The "Original" salmon-colored Streamline tendon has been the subject of some criticism on that score. I use Chinook black tendons, and just flex them all around before each use. If there's any evidence of cracking it's time to replace. In any case I replace them about every two years whether there's any sign of degradation or not, and I think most sailors replace even oftener than that.

I replace mine when it looks worn, which aint often enough I fear. but my mate yesterday suggested replacing it every autumn this way its new for cold weather when you are more likely to die and also I guess its more brittle when colder.

Remind me how you felt about your wingding experiment. Still plan to twin leash and twin mast?

I have the "Original" salmon-colored Streamline tendon on two bases that are 7 and 5 years old (2-bolt and 1-bolt bases) and in the constant heat of Florida, both look fine and work perfect, only been using the 5 year old 1-bolt base regularly for the last three years year-round. Bought a spare Streamlined tendon just in case, but have not needed it so far. I have heard of people using tendons for 15 years without breaking, and still using them!

After breaking tendons which looked new I now replace them every year. They break at the point where they are drilled to accept the cross screw, so are impossible the properly inspect without complete disassembly. By the time you do that, you might as well replace the tendon for cheap piece of mind.

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jdfoils said..
After breaking tendons which looked new I now replace them every year. They break at the point where they are drilled to accept the cross screw, so are impossible the properly inspect without complete disassembly. By the time you do that, you might as well replace the tendon for cheap piece of mind.

When I was replacing the Streamlined single bolt base "bolt" with a longer one to add a 3/4" insert so the mast would not hit the Bolt concave deck ridge, I had to dissasemble the mast base and got to inspect the tendon, looked almost brand new after 5 years of year-round use in Florida heat. But I did make sure that when I reassembled the mast base to make the safety line light, so in worse case tendon breaks on the water and safety line holds it together until I get back to shore.

When you sail back on the safety line the broken base beats the #%*! out of your board. Definitely do not recommend.

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jdfoils said..
When you sail back on the safety line the broken base beats the #%*! out of your board. Definitely do not recommend.

If the safety lines are short the broken tendon/base will land on the deck plate. I take off the supplied blue/black rope and use formuline.

I replace each year

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jdfoils said..
After breaking tendons which looked new I now replace them every year. They break at the point where they are drilled to accept the cross screw, so are impossible the properly inspect without complete disassembly. By the time you do that, you might as well replace the tendon for cheap piece of mind.

Pretty much this. ^^^
i always have a new one ready, pull the mast base apart every 6months for a look over. They can be fine on the exposed part and break at the bolt hole, which you cant see when the mast base is assembled.

pulling it apart, you'll be able to determine if it really needs replacing or not, but once a year is a pretty good rule to follow

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Subsonic said..

jdfoils said..
After breaking tendons which looked new I now replace them every year. They break at the point where they are drilled to accept the cross screw, so are impossible the properly inspect without complete disassembly. By the time you do that, you might as well replace the tendon for cheap piece of mind.

Pretty much this. ^^^
i always have a new one ready, pull the mast base apart every 6months for a look over. They can be fine on the exposed part and break at the bolt hole, which you cant see when the mast base is assembled.

pulling it apart, you'll be able to determine if it really needs replacing or not, but once a year is a pretty good rule to follow

Guessing you guys do not have Streamlined bases and tendons!, short safety lines "on a Streamlined base" will keep the base together and prevent damage to the board, that is how it was designed to work guys! And Streamlined bases come with white formula line from what I can tell, not blue black line.

BUT I am not a wave sailor, and rarely go through a shore break for foiling, shore pound really beats up equipment and that includes the UJ, so if you are going through shore break regularly then keeping an eye on the tendon is a good idea as stated above!

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Awalkspoiled said..
There's some evidence that they just plain age even without use, especially if they've been subjected to extremes of heat or cold. The "Original" salmon-colored Streamline tendon has been the subject of some criticism on that score. I use Chinook black tendons, and just flex them all around before each use. If there's any evidence of cracking it's time to replace. In any case I replace them about every two years whether there's any sign of degradation or not, and I think most sailors replace even oftener than that.

I can definitely believe that.

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Subsonic said..

jdfoils said..
After breaking tendons which looked new I now replace them every year. They break at the point where they are drilled to accept the cross screw, so are impossible the properly inspect without complete disassembly. By the time you do that, you might as well replace the tendon for cheap piece of mind.

Pretty much this. ^^^
i always have a new one ready, pull the mast base apart every 6months for a look over. They can be fine on the exposed part and break at the bolt hole, which you cant see when the mast base is assembled.

pulling it apart, you'll be able to determine if it really needs replacing or not, but once a year is a pretty good rule to follow

I think this is what I will start to do. I've never broken one, but I don't want to push my luck too much either.

Inspect them before every session. Bend by hand and check for cracks. Cracks will be stress risers and cause failure.

I have had MUCH better luck with tan Streamlined tendons than with the black Chinook tendons.

Full disclosure: I think I got a bad batch of Chinooks. Three of them failed while brand-new. The shop replaced them for free. Many people have gotten a good long life out of them.

Good topic. What I have been told is the tendons (Chinook) deteriorate over time and that climate plays a role.

The full time folks in Maui advise to change them every year and make sure the supplier provides you with a new tendon as they deteriorate just sitting in storage. So use plays a role but time, in a Maui climate, also has an impact.

As others have noted checking it quickly before each session is the way to go

Checking before each session does no good because if there is a crack it will be inside the sleeve and not visible.

In my personal experience (twice!) the safety line on a streamlined base will keep the rig attached, but will not keep the broken part over the base plate and there will be damage to the board around the mast track which will make repairs difficult.

For me, the black Chinook ones are less prone to cracking than the tan streamlined ones. I have broken streamlined ones that look new, with the logo still clearly legible.

My failures are from wave sailing, not foiling.

There are factors common for Windsurfing & Windfoiling that impact UJ selection and tendon or Hour Glass wear.
This is Windfoiling / Foiling Forum.
In windfoiling there is much less stress on UJ & the mounting (unless you frequent catapult, faceplant, breach and fall).

Lets talk specifically about Windfoiling:
For example in Seattle Area WA, USA a lot of people switched to purely mechanical joints specifically for Windfoiling.
However, there is also another solution called "Chinook Pro Flex".
There is still an insertable tendon but that tendon is inside a swivel so less stress.
I started to use "Chinook Pro Flex" in October 2020 and have put on it about 4000 miles mostly using sails 9m-12m (yes, windfoiling) and I am above 200LB (90kg) and I do sometimes ride "foil assisted planing" (cushioned load on UJ comparing to pure finning).
I only had one problem with it when one nut got lose and got lost but the bent bolt was still holding.
If you are interested in more details:
groups.io/g/nw-windtalk/message/72074



There are obviously also "common" factors for windsurfing & windfoiling over last 40 years discussed and reported by sailors:
a) UV - some composite / plastic components just fall apart with UV exposure
b) cold - some composite / plastic components just fall apart in e.g. freezing temperature (lose flexibility, become brittle)
c) heat - some composite / plastic components just melt away or wear out in too much heat
d) bad batches - there were many bad batches of tendons (in particular yellow/orange) reported over the decades

I personally had more failures of tendon joints living and windsurfing in Sydney AUS in late 1990s (more UV, bad batches ?) then moving to the Seattle, WA, USA then using both tendons and "hour glass" joins. "Hour glass" have been much more robust and rarely failed, That was at least my experience. They also come now with webbing ribbon to prevent separating rig from the board when flexing material fails.

Replacing the tendon is a balancing act between increasing risk of component failure and your "wallet impact".

Fully agree with comments above: "if you bend it and see cracks it is time to replace it for sure".

No windsurf shops in/around ACT, wheres a good shop to get a replacement in Perth? I'll be over for 2 weeks.

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Adam in NSW said..
No windsurf shops in/around ACT, wheres a good shop to get a replacement in Perth? I'll be over for 2 weeks.

Revolution board sports in osborne park or
2nd wind sailboards in attadale or
Surf sail in leederville.

you could also try windsurfing perth in myaree, but Reg seems to be orientating towards winging now, so not sure what stock he'll have windsurfing wise.

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mareks360 said..
There are factors common for Windsurfing & Windfoiling that impact UJ selection and tendon or Hour Glass wear.
This is Windfoiling / Foiling Forum.
In windfoiling there is much less stress on UJ & the mounting (unless you frequent catapult, faceplant, breach and fall).

Lets talk specifically about Windfoiling:
For example in Seattle Area WA, USA a lot of people switched to purely mechanical joints specifically for Windfoiling.
However, there is also another solution called "Chinook Pro Flex".
There is still an insertable tendon but that tendon is inside a swivel so less stress.
I started to use "Chinook Pro Flex" in October 2020 and have put on it about 4000 miles mostly using sails 9m-12m (yes, windfoiling) and I am above 200LB (90kg) and I do sometimes ride "foil assisted planing" (cushioned load on UJ comparing to pure finning).
I only had one problem with it when one nut got lose and got lost but the bent bolt was still holding.
If you are interested in more details:
groups.io/g/nw-windtalk/message/72074



There are obviously also "common" factors for windsurfing & windfoiling over last 40 years discussed and reported by sailors:
a) UV - some composite / plastic components just fall apart with UV exposure
b) cold - some composite / plastic components just fall apart in e.g. freezing temperature (lose flexibility, become brittle)
c) heat - some composite / plastic components just melt away or wear out in too much heat
d) bad batches - there were many bad batches of tendons (in particular yellow/orange) reported over the decades

I personally had more failures of tendon joints living and windsurfing in Sydney AUS in late 1990s (more UV, bad batches ?) then moving to the Seattle, WA, USA then using both tendons and "hour glass" joins. "Hour glass" have been much more robust and rarely failed, That was at least my experience. They also come now with webbing ribbon to prevent separating rig from the board when flexing material fails.

Replacing the tendon is a balancing act between increasing risk of component failure and your "wallet impact".

Fully agree with comments above: "if you bend it and see cracks it is time to replace it for sure".

Thanks mareks that was good information, one problem I have in setting up the kit in high winds and waves with the Streamlined tendon base is it will help to lift the board into the air allowing the wind to get under it. The Chinook Pro Flex is supposed to eliminate that problem, will have to think about it. Also, I store my kit on the beach during breaks with the board flipped over onto the mast, and that does keep the tendon in a bent position, probably not good for it but still good after 5+ years!

Wondering if there is any issue with using the Chinook Pro Flex Euro pin single bolt base with a Streamlined Euro pin extension, should not be because they are both Euro pin, right?

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mareks360 said..

I started to use "Chinook Pro Flex" in October 2020 and have put on it about 4000 miles mostly using sails 9m-12m (yes, windfoiling) and I am above 200LB (90kg) and I do sometimes ride "foil assisted planing" (cushioned load on UJ comparing to pure finning).

I have one of these, nice for windfoiling. Originally I bought it for Windsurfing for my wife, who struggles with the board flipping over, but after a while (I believe after breakages recorded by Chinook), Chinook amended the warranty on site to state this was ONLY for Windfoiling; not Windsurfing. A shame as it works well for both.

chinooksailing.com/products/1-bolt-pro-flex-mast-base-euro-pin-ex

"
1-Bolt Pro Flex Mast Base Euro-Pin EX (FOR FOILING USE ONLY)
"*** Specifically designed for Foiling (Not recommended for Bump and Jump, Slalom or Formula Racing. If used as such warranty is null and void**"

k.

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Sandman1221 said..

Wondering if there is any issue with using the Chinook Pro Flex Euro pin single bolt base with a Streamlined Euro pin extension, should not be because they are both Euro pin, right?

I have been using Chinook Pro Flex with Duotone Power XT 2.0 (ratchetable extension) and I am extremely happy with it.
I sometimes use sails that require much stronger downhaul like for example Sailworks NXes (9.1m, 9.9m & 10.8m) therefore no winch needed. Also so much convenience.
I think, it is important that you do not use anything like Surfbent that may unintentionally press the button and release the Euro Connector.
Most people in US use US Cup connector (instead of Euro), therefore nobody reports any issues.
However Duotone Power XT 2.0 only comes with Euro pin connector.
I use double bolt chinook plate (quick disconnect) on all my boards therefore can not comment on single bolt.

I replace tendons every year because they will not survive two years without breakage. Given that, I won't even consider the significantly weaker pro flex universal which does not properly support the mount at the top of the tendon. If you want more flex, go with the soft spongy hourglass universal. I use the same universal, masts, sails, extension, and booms for all disciplines; wave, freestyle, and foiling. Don't see a need for specialized gear other than the board and foil.

Any tips on getting those chinook buggers apart - tried once and gave up...

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joe87879 said..
Any tips on getting those chinook buggers apart - tried once and gave up...

The old ones with the Phillips screws or the modern ones with the hex bolts?

Philips screws...

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joe87879 said..
Philips screws...

Get the slots as clean as possible and two really good screw drivers. I'll check what size I used (I think #2?) but cheap screw drivers tend to have a sloppy fit and that makes it way too easy to strip the heads. One side is just a screw and the other is "sex" or Chicago bolt



You may have to tap that out with a punch. You can use the opposing screw as a punch if you unthread it just a couple of turns to get it started or another screw of same thread. iirc, the threading is imperial but I haven't done one in about 3-4 yrs so ... my memory may not be accurate.

As old as those are now, may be worth getting a modern one with hex bolts just to make this process easier. But it's easy to say that and spend other people's money.

It was assembled using red locktite. Mount one screwdriver in a vice and address the other side with an impact driver, the shock load usually breaks the bond. If that doesn't work then heat it and the locktite will give way.

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jdfoils said..
It was assembled using red locktite. Mount one screwdriver in a vice and address the other side with an impact driver, the shock load usually breaks the bond. If that doesn't work then heat it and the locktite will give way.

Forgot that the screws were in aluminum so was hesitant to suggest heat if the cups were plastic. Impact driver is good idea if one is available.

I have had to just drill them out and replace with new ones. Florida hypersaline water is murder on that stuff.

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Subsonic said..

Adam in NSW said..
No windsurf shops in/around ACT, wheres a good shop to get a replacement in Perth? I'll be over for 2 weeks.

Revolution board sports in osborne park or
2nd wind sailboards in attadale or
Surf sail in leederville.

you could also try windsurfing perth in myaree, but Reg seems to be orientating towards winging now, so not sure what stock he'll have windsurfing wise.

thanks for the info, will be going to Revolution anyway to check out the Aliens :)