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Anybody using Chinook Pro Flex bases?
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dhmark



Joined: 04 Sep 2007
Posts: 376

PostPosted: Tue Apr 13, 2021 11:48 am    Post subject: Anybody using Chinook Pro Flex bases? Reply with quote

Several months ago Chinook introduced Pro Flex base which the cup or pin swivels on top of the tendon, thus allowing it to flex easily to 90 degrees for ease of attachment. They say it also reduces wear on the tendon (makes sense). It's a "semi" mechanical u-joint in that it only has one swivel dimension rather than 2. Although the pin/cup can form any angle relative to the base without bending the tendon, it requires the tendon to spin at the base to change some angles, whereas a full mechanical u-joint can form any angle without any spinning.

Conceivably this changes the force required for certain rapid movements of the pin, sometimes spinning (low force), sometimes bending the tendon (higher force), or a combination of both. A full mechanical u-joint or tendon u-joint will require relatively uniform force in any change of angle. Maybe that doesn't make any difference because these forces are trivial relative to the torque applied by the rig. Anybody using this product, and is there any downside at all? Price difference is minimal, improvement in tendon longevity would be a great positive.
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killeen_john



Joined: 04 Aug 2006
Posts: 61

PostPosted: Tue Apr 20, 2021 1:34 pm    Post subject: Reply with quote

I picked up a Pro-Flex 2-Bolt Quick Release "Upper" US Base Cup from Windance in December but, haven't had a chance to try it out yet. My primary motivation to buy one verses my current mechanical joint was wanting the safety line in the event of a failure as well as a little shock absorption.

I like using the regular mechanical joint on my formula board but, it has no shock absorption whatsoever and the posts about Chinook mechanical joint failure made me a little nervous about them coming undone.

It also feels like there's a certain rotation angle where the mechanical joint binds up ever so slightly and doesn't rotate freely however, this hasn't caused me any problems yet. The Pro-Flex seems to allow a greater range of motion thanks to the tendon although the jury is still out on the actual benefit here.

Lastly, the Pro-Flex joint assembly is a bit shorter overall than the mechanical joint if that matters any.
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us85



Joined: 29 Aug 1999
Posts: 47

PostPosted: Fri Apr 23, 2021 11:35 am    Post subject: Reply with quote

I got single-bolt version just to make adjusting the mast base position easier out on the water (for foiling). All my other bases are 2-bolt, so I'm not really sure how much it helps.
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dhmark



Joined: 04 Sep 2007
Posts: 376

PostPosted: Sat Apr 24, 2021 11:08 am    Post subject: Reply with quote

I think its too hard to change mast base position on the water with the sail attached, there's just too much friction or bending (of tendon) necessary with various forces. What you want is ease of connecting sail to board on the water with board and sail lying flat. This would be either mechanical or pro flex u joint and Euro-pin system, US cup would be OK but a little harder. Once sail is off, one-bolt is easiest and fastest, and I have always trusted it.
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windyjoe



Joined: 04 Jul 2008
Posts: 17

PostPosted: Sat Apr 24, 2021 4:56 pm    Post subject: New joint Reply with quote

Good for foiling when uphauling not good and really sucks when water starting joint hangs up 90 deg from mechanical joint flips board over drove me nuts till I figured out what was going on foil uphauling great joint centers up and works fine[/u]
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wsmtbskate



Joined: 09 Jun 2010
Posts: 124

PostPosted: Sun Apr 25, 2021 7:59 pm    Post subject: Reply with quote

I got a single bolt, europin frankenbase for foiling last year.
works great, no complaints
makes getting the rig on and off much easier when board is in the water,
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dhmark



Joined: 04 Sep 2007
Posts: 376

PostPosted: Wed Apr 28, 2021 8:48 am    Post subject: Re: New joint Reply with quote

windyjoe wrote:
Good for foiling when uphauling not good and really sucks when water starting joint hangs up 90 deg from mechanical joint flips board over drove me nuts till I figured out what was going on foil uphauling great joint centers up and works fine[/u]


I got a single-bolt version and tried it for the first time. I'd always used rubber UJ before, had tried regular tendon once before, thought it felt the same. The problem noted above is because when the tendon can't spin (or is hindered from spinning due to friction from other forces), certain motions 90 degrees apart require the tendon to bend and others the mechanical joint flexes. In between the joint will want to flex (path of least resistance) putting some odd force on the board. I didn't notice this happening to me sailing my small board in high winds, wind was catching the board all the time (but maybe due to this issue?). When down in the water I could see that the tendon was straight, UJ bending solely with the mechanical joint, while the whole thing spinning at the base, zero stress on the tendon. This bodes well for longevity of the tendon.

I also noticed that the tendon is much shorter than standard Chinook tendon, and the holes drilled parallel rather than at 90 degree orientation. I asked Chinook about this, they said no problem, the tendon doesn't need full flexion. I'm only sort of satisfied by this answer, would rather have the standard length tendon, maybe this causes the board flipping problem that windyjoe complains about.
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dhmark



Joined: 04 Sep 2007
Posts: 376

PostPosted: Wed Oct 06, 2021 11:17 am    Post subject: Reply with quote

Latest information on Pro-flex from the Chinook web site is that it is now specifically recommended only for foiling and that high performance use (B & J, slalom, formula) will void the warranty. Well that sucks, I did not buy it for foiling. I wonder what the durability issues were with the product.
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boardsurfr



Joined: 23 Aug 2001
Posts: 1266

PostPosted: Wed Oct 06, 2021 12:13 pm    Post subject: Reply with quote

I have used one for foiling only, and the tendon broke after one year (Chinook replaced it for free). There was no visible damage before it broke. With regular Chinook bases, tendons last several years, and typically show signs that they should be replaced before they break.

This is just a single case, but the change on the Chinook web site indicates that others may also have seen problems. Seems the tendon in the Pro Flex base breaks more easily, even when used only for freeride foiling, where the forces are a lot lower than in windsurfing (and especially slalom/speed sailing). The tendon is a bit shorter, but I doubt that's the cause of the problem. I think it is more likely that the restrictions on movement of the mechanical part sometimes cause excessive force. At times, there are some jerking movements from the joint, especially during or after uphauling, that do not happen with regular tendon or rubber bases.

For foiling, the Pro Flex base is great, since it can be hard to impossible to put the board on the side to connect or remove the sail. I never had any issues when water starting with it, either. But I won't use it for windsurfing, and would expect that tendon longlivity is reduced, not increased, compared to standard bases.
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dllee



Joined: 03 Jul 2009
Posts: 5328
Location: East Bay

PostPosted: Wed Oct 06, 2021 12:33 pm    Post subject: Reply with quote

Mech base for foiling.
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