Broken ST Turbo Fin Mast Rod

This week while peddling my Outback across a lake I suddenly lost all power. Not unlike slipping a tranny gear. I pulled up my MirageDrive to discover a sheared mast rod - snapped clean off the machined cut for the set screw . I paddled my way home. Fortunately, I wasn't miles from base as I'd been the week before!

Unfortunately, I have a trip planned with other 'yakers to water trail camp along miles of Lake Superior in a couple weeks.
Two potential problems with that:

1) I need a new mast rod

2) Do I trust the turbo mast to not leave me "stranded" with only a light paddle and a wide boat to navigate by arms?

I'd be most interested to find if others have encountered the same failure with these rods. I'm a rather fit 56 year old, but I suspect no match for the legs of say, a 22 year old kid with boundless energy.

There's a lot of water pressure dynamics going on under these boats. In talking with the machinist (an avid yakker) that extracted the small end of the broken rod, he questioned how light the rods appeared relative to the force of water pressure applied on the masts. He also suggested that such a deep flat-cut in the metal for the set screw created unnecessary weakness. A simple dimple in the rod used with a pointed set screw might work as well without diminishing the integrity of the metal rod.

Anyway, I need another mast rod . . . Soon!

Any help out there?

Dan in Duluth








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Hi Dan,

As I recall, you installed these about a year ago, so you might check with your dealer about a warranty replacement. The current masts are 1/4" shorter than your older style, so you may want to trim your remaining mast to match the new or order a pair and keep your old one as a back-up. IMO, a good dealer would borrow a pair of masts from an existing Turbofin set and give them to you, replacing them when the replacements arrive. Here's a link showing the difference:

http://www.hobiecat.com/community/viewtopic.php?t=5962

On the other hand, your machinist friend should have a piece of 1/4" stainless bar stock to simply cut a new mast. A little quick file work will create the flat spot you need and voila! If he doesn't have any, your local metal supplier or salvage yard, should do. You might even find somethi8ng at the local hardware. Use your remaining mast as a pattern.

Yours is the first mast that I've heard of breaking. They'll almost always bend on major impact and can be straightened several times. It sounds like an impurity in the steel, and I'd guess this sort of thing happening again to you is about as common as a force 5 tornado landing in Southern California -- slim to none.

I'm sure your machinist knows his business, but he should know this rod is plenty strong for its task and can handle a lot more than your Turbofins. Further, the torque axis is applied 90 degrees to the groove, making it's effect on directional strength minimal to negligible.

So, either way, you should be back in business in plenty of time for your trip and I wouldn't worry about it happening again.

Thanks Roadrunner for the info.

I'll shoot a note to my dealer, Brad in N St. Paul. See what he can do for me.

I posted here initially to get responses from others who might have sheared a mast.

So far, it appears I'm the only "chosen one"

-Dan

Hey Roadie
My Turbo Fin mast broke about 1/8" above the sprocket mast hole just two weeks ago on our China Camp Trip.. http://www.hobiecat.com/community/viewtopic.php?t=6971
I found out my Turbo Fin masts measure 7mm in diameter. I dont know if the mast material used is 316 stainless like the hex bolts or 304 stainless like the small machine screws but 1/4" diameter round rod was to small for my sprocket and 5/16 would have been too big. Thats why I measured it and then found that it was closer to 7mm than anything else. I thought it was a funny size for Hobie to use but thats what mine seem to be..Please measure yours sometime and let me know what you get . Im just curious...
- Thanks -
-Kepnutz-

Kep, I think you're right! I measured it in haste. Also, I had missed the broken mast in your post -- was thinking it was a mast sprocket. Thanks for keeping me honest! I'm taking it all back before I'm proven wrong on anything else!

Dan, sorry for the bad info. Hopefully your Hobie dealer will have you up and running in no time!

Hey Ya Roadie-Oh
Its no worries mate..for all I knew your masts and sprockets and Mettmann's masts' and sprockets were in fact 1/4" diameter round.
After all I have three different lengths of Turbo Fin Masts....yup.. I repeat..three different lengths of Turbo Fin Masts.
I did not assume your diameter measurment was wrong just that mine was different and maybe Hobie changed specs on parts so I just wanted to confirm the sizes.
Anywho I still have three different legnths of Turbo Fin Masts..so there..
.........Have fun.......... take it easy
...........Kepnutz...........

No problem, Roadie (Beep Beep)

Just glad to get a knowledgable response from you folks in Hobie Mirage World.

I followed up on your advice and sent a note to my dealer who, get this . . . sends a reply on a Sunday, no less! He seemed somewhat surprised by the photo I sent of the break, and agreed to follow-up with a claim.

Well, here . . . read for yourselves:

"Whoa, you win the award for that one Dan. That’s the first time I’ve seen that.



Molly will email this claim to Hobie on Monday. She’ll also check to see if they can send the replacement part directly to you.



I’ve not seen one of these break before so I’m don’t know for sure but I’d be surprised if this wasn’t a no charge warranty replacement.



Glad you’re having fun with your boat. We’ll do everything we can to get you back out on the water with your big fins ASAP.



Have a great day"



Brad



Brad Nelson, President

Hi Tempo Ski Snowboard and Sail

3959 N Hwy 61

White Bear Lake, MN 55110


I'd post a photo of the break if I knew how to attach it to this forum page

Thanks to you and Kep for the replies,

- Mettmann -
back on the water, soon

The same thing happened to mine. Snapped right at the set screw cutout. (Pics Below) I forgot to bungie my fins up while fishing the flats and then someone in a O***n brand yak said he didn't like the Hobies cause ya can't sit side sadle. So, my middle name being Dumbass I said sure you can and promplty sat on in not realizing that the fins were pointing towards the sand bottom. Snap. Totally my own fault. I ordered one from Barrell and I'm waiting for it to come in.

I do think that when I get the chance I will go to my local metal dealer and buy some stainless rod and make two without the cut outs. (And an extra)

Matt. Quick question. Is ther a specific number of stainless that I should get?