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Turbo Fins Disappointment
http://www.hobie.com/forums/viewtopic.php?f=11&t=3613		 Page 2 of 2
Author:  Roadrunner [ Mon May 22, 2006 10:03 am ]
Post subject: 
AlohaDan wrote:
If there is rubbing it should not take long to see some wear.
Hi Dan,

To be quite honest, any rubbing would be insignificant. When you get your new fins, you will see that as the fin flexes, it draws the sproket guard forward. To the extent that there's friction, it's way overshawdowed by the small friction caused by the rotation of this piece on the drive shaft, universal to all applicatons. Even without any flexing, you can reposition the sporket guard forward. IMO, in the scheme of things (1 to 10 scale) this barely rates a one.

This is not to diminish Windrider's astute observations. His attention to detail is commendable and, no doubt, taken note of by the Hobie engineers.

The picture below illustrates the advancement of the Hobie drive. You can see the new drive is much more streamlined. Even the old fins have undergone a significant evolution, particularly in their early days. My point here is these new fins are the first generation and will undoubtably undergo the same refinement process as the rest of the Hobie gear. Personally, I think Windrider is pretty pleased with his new fins now that he's tried them out. That's too bad -- I was hoping to pick up a second set from him on trade!

Let me point out, the "misalligned" gap is actually in the same place as the old fin. If you look at the picture closely, you will see the newer fin rides a little closer to the shaft, pushing the gap forward. Remember the new fins are retrofits for that old drive also. The sproket guard shift caused by the longer clew mount is something I can accept as a consequence of the enormous efficiency and power advantage the new fins deliver. 8)


Image
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PS Those dark spots on the new fins are water.
Author:  mmiller [ Mon May 22, 2006 4:42 pm ]
Post subject:  Alignment
Just back in town from a Hobie event in New York.

Yep, the chain cutout gap makes them look mis-aligned. There was some last minute change in the mast alignment in the mold due to some thickness and injected plastic flow issues. This is not effecting the performance. That pulled the whole fin a little forward. We may revise the mold at a later date. Not a simple task.

The fins have always touched or nearly touched the sprocket guards on the old fins. NO problems there.

There can be a bigger gap if the masts are flipped end for end. They are different for the two models. They may have slots in both ends of the masts.
Author:  Yellowkayak [ Tue May 23, 2006 12:48 pm ]
Post subject: 
I know these are adjustable fins, for stiffness. If you look at the right of the fin you will see an adjustment thumb nut. If you tighten these, then that will pull the fins UPWARDS, and back them off will pull them DOWNWARDS. Sense this is an adjustable fin that gap will close and open denpending on the fin adjustment. Matt am I wrong here? Looks like a good design to me and I don't see any design or performance problem.


JJ
Author:  OffRoad [ Tue May 23, 2006 3:01 pm ]
Post subject: 
Hi JJ

Windrider was concerned mostly on the gap at the aft sprocket guard which is now rubbing on the aft side of the frame due to the width of the sail.

As Roadrunner has pointed out the sail will flex under motion which will relive this pressure giving it the clearance it needs.

The gap between the top of the sail and sprocket housings are necessary for adjustment as you have pointed out.

The alignment of the chain to the cutout in the top of the sail is only cosmetic. Hobie would do well by either removing the cut out or widen it in the future sails to keep chit chat down.
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