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Mirage drive mast torture
http://www.hobie.com/au/en/forums/viewtopic.php?f=71&t=35663		 Page 1 of 1
Author:  walt [ Thu May 19, 2011 7:15 pm ]
Post subject:  Mirage drive mast torture
I’ve had my AI for about a year now, absolutely love it.

I’ve bent the drive masts now a few times in shallow water groundings. For the most part, I just bend them back and keep on using them. It would seem that after being bent back - good as new.. Last time I bent them, I just popped the drive out and bent the mast back by hand out on the water.

It seems to me that I can probably keep doing this many more times.. Should I be more worried about this? Anyone actually wore a mast out so that it won’t hold it shape during normal peddling?
Author:  augaug [ Thu May 19, 2011 7:47 pm ]
Post subject:  Re: Mirage drive mast torture
I think most people wear out fins first! I haven't heard of too many masts being replaced, but it does happen.
Author:  Roadrunner [ Thu May 19, 2011 10:23 pm ]
Post subject:  Re: Mirage drive mast torture
walt wrote:
I’ve bent the drive masts now a few times in shallow water groundings. It seems to me that I can probably keep doing this many more times.. Should I be more worried about this? Anyone actually wore a mast out so that it won’t hold it shape during normal peddling?
IMO the mast begins to crystallize at the bend and become brittle at that spot -- each bend weakens it a little bit and it can eventually break without warning. It looks like this:
Image

Your safest option is to replace the mast(s) at this time. Or you can keep one spare mast and sprocket on hand as replacements when an existing one fails. The sprocket is advisable in case there is no mast nub left to spin the mast base out (your Easy-Out option will not necessarily work in this situation). In that event you would need to replace the sprocket as well.

If you decide to go with option #2, be sure you are current on your one-fin operational procedures. :wink:
Author:  abonnin [ Thu May 26, 2011 4:30 am ]
Post subject:  Re: Mirage drive mast torture
One fin operational procedures? Please explain. Apologies to all Australians for whom that phrase is traumatic :mrgreen:
Author:  Roadrunner [ Thu May 26, 2011 2:35 pm ]
Post subject:  Re: Mirage drive mast torture
abonnin wrote:
One fin operational procedures? Please explain.
This should cover it: viewtopic.php?f=11&t=8240&hilit

Here's a confirming opinion:
AlohaDan wrote:
I will verify Roadrunners statement of using a single fin. Effective enough to get you home..


This is a GPS printout of a one-Turbofin cruise on an Adventure -- not as bad as one might expect. Note the relatively weak acceleration. Obviously the AI would be a bit slower and more subject to wind and chop.
Image
Note: An overly tightened fin clew gives more rock and roll, less thrust.

Quote:
Apologies to all Australians for whom that phrase is traumatic :mrgreen:
Please explain. :?
Author:  Fly4v [ Sat May 28, 2011 12:01 am ]
Post subject:  Re: Mirage drive mast torture
I have found that the sprockets are the weak spot. How is it that the fin mast is bent and not shear the teeth on the plastic sprockets?
Author:  ELM [ Sat May 28, 2011 4:10 am ]
Post subject:  Re: Mirage drive mast torture
One fin and apoligies to us aussies would be DarDap DarDap DaDaDaDa Jaws

Fly4v wrote:
I have found that the sprockets are the weak spot. How is it that the fin mast is bent and not shear the teeth on the plastic sprockets?

Probably because of forward motion and the collision bends just the mast where as a side impact would put pressure on the sprocket.

Wouldn't it be easier to just be more careful and protect your drive. In my first twelve months of owning one, I constantly bent fin masts and destroyed a set of fins. Then I just got smart about how and when to use the mirage and have not bent a mast in many years, it's a far better way to go.
Author:  Roadrunner [ Sat May 28, 2011 12:32 pm ]
Post subject:  Re: Mirage drive mast torture
Fly4v wrote:
I have found that the sprockets are the weak spot. How is it that the fin mast is bent and not shear the teeth on the plastic sprockets?
How many sprockets have you had fail? 8)
Author:  Fly4v [ Sat May 28, 2011 12:53 pm ]
Post subject:  Re: Mirage drive mast torture
Third sprocket in nine months. It is always the front one on the turbo drive. I don't hit bottom and pull the drive before the boat ramp and beaching. The cable and chain tension are correct.
Have two other standard drives one almost two years old and never a failure.
The only modification to the turbo drive is the bolt through replacement of the adjustment pins and the other holes are filled with epoxy. The plastic there failed also.
The scary part about the last sprocket failure was the when of the failure. I was taking my sister in law out for a quick sail and it did the pop and slip. But that was just after a 26 mile off shore solo trip and the one thing I didn't have was a spare drive. Think that was my free warning.
Author:  Roadrunner [ Sat May 28, 2011 2:52 pm ]
Post subject:  Re: Mirage drive mast torture
Fly, three failures, one location -- I don't think you have a sprocket problem, but rather a chain problem. One or more links may be too narrow, causing the chain to ride over one or more cogs and ultimately chewing the cogs up. Visually, it would look something like this:
Image

If you cycle the Drive by hand, you would feel a little "lumpiness" where that link jumps on and off the first cog, as opposed to a smooth cycle throughout the normal (180 degrees) operational range.

I have bent several masts, broken a few and even straightened them side to side where the sprocket takes the full force of the bend -- never had a sprocket cog break, chip or wear out. Hopefully, a chain replacement will solve your problem. 8)
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