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Anybody using Chinook Pro Flex bases?
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us85



Joined: 29 Aug 1999
Posts: 45

PostPosted: Wed Oct 06, 2021 3:08 pm    Post subject: Reply with quote

Yeah, I definitely wouldn't a mechanical base or the flex-pro for fin windsurfing (other than long board).

At least the Pro Flex has rope as a safety if the joint fails.
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dllee



Joined: 03 Jul 2009
Posts: 5181
Location: East Bay

PostPosted: Wed Oct 06, 2021 3:26 pm    Post subject: Reply with quote

Mech is pretty good for flat water slalom.
Hardly notice a diff from rubber uni.
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dvCali



Joined: 23 Aug 2007
Posts: 1301

PostPosted: Thu Oct 07, 2021 1:44 am    Post subject: Reply with quote

boardsurfr wrote:
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.

ah ... that's too bad. I have two Pro-bolts on my two slalom boards. I picked a second one because I liked not having to detach the joint every time I put the board on the rack inside my van. They work great ... but lovely to hear that they are now not recommended for slalom ...
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dhmark



Joined: 04 Sep 2007
Posts: 372

PostPosted: Thu Oct 07, 2021 10:51 am    Post subject: Reply with quote

dvCali wrote:

ah ... that's too bad. I have two Pro-bolts on my two slalom boards. I picked a second one because I liked not having to detach the joint every time I put the board on the rack inside my van. They work great ... but lovely to hear that they are now not recommended for slalom ...[/quote]

You might be mistaking the pro-flex UJ which is a specific mechanical+tendon UJ for the 2-bolt deck plate, which is not specific to any UJ. Nothing wrong with those.
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dhmark



Joined: 04 Sep 2007
Posts: 372

PostPosted: Thu Oct 07, 2021 11:05 am    Post subject: Reply with quote

boardsurfr wrote:
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.



I would think that the shorter tendon would make a difference, more stress when the tendon has to bend rather than the hinge and rotation working. With certain forces, the rotation will bind up. Without the rotation, the forces needed to bend the UJ are very uneven, very little needed in the axis of the hinge, a lot needed perpendicular to the hinge. But if the tendon is equally flexible, it seems that the forces should always be LESS than a standard tendon, which has completely restricted motion.

I also sense that the tendon material in my pro-flex seems different. The pro-flex tendon is dullish black, standard tendon is shiny black, the pro-flex seems like it is more brittle.


Last edited by dhmark on Thu Oct 07, 2021 3:42 pm; edited 1 time in total
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grantmac017



Joined: 04 Aug 2016
Posts: 946

PostPosted: Thu Oct 07, 2021 11:55 am    Post subject: Reply with quote

I don't have a pro-flex but I was going to get one for foiling. Tempted to install the regular tendon into it since I only really want the hinge for easier separate carry.
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dhmark



Joined: 04 Sep 2007
Posts: 372

PostPosted: Sun Oct 10, 2021 3:08 pm    Post subject: Reply with quote

boardsurfr wrote:
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.


Is this the one-bolt or the 2-bolt version? I tried swapping the pro-flex from a single-bolt base to a 2-bolt base (trivially easy to do) and the 2-bolt version has much less friction to spinning on its vertical axis. If it was single bolt, I think the jerking might be the friction to spinning alternately seizing and releasing as the tendon tries to straighten out.
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