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Done!!
http://www.hobie.com/forums/viewtopic.php?f=13&t=46108		 Page 1 of 1
Author:  wscotterwin [ Sun Dec 30, 2012 6:41 pm ]
Post subject:  Done!!
Done, Courtesy Hobie 18 North Americans. :mrgreen:

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Author:  wscotterwin [ Sun Dec 30, 2012 6:51 pm ]
Post subject:  Re: Done!!
Oh yea, different boat, but it was Completely "Done" courtesy of the Hobie 18 North Americans in Mohave. :o

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Check out one of the contributing factors!

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Author:  DVL [ Mon Dec 31, 2012 8:00 am ]
Post subject:  Re: Done!!
Thanks for the heads up. I and other Hobie 18 owners should be (will be) checking that as well as the crossbars and rigging.

We need to remember that all metals have a fatigue factor and will ultimately fail.

I prefer to learn lessons from others mistakes.
Author:  srm [ Mon Dec 31, 2012 8:13 am ]
Post subject:  Re: Done!!
Yep, that seems to be a common failure point for the H18 crossbars.

It is definitely important to make sure you keep the mast step solidly attached to the crossbar. Correct any slop immediately by re-riveting the step. On my 18, I also bedded the step in epoxy last year and it seems to have help it stay rock solid to the crossbar. Also make sure you keep the dolphin striker good and tight. Rinse with fresh water whenever possible, and inspect regularly.

sm
Author:  MBounds [ Mon Dec 31, 2012 11:07 am ]
Post subject:  Re: Done!!
Interesting that the crack develops there. That means the top of the crossbar is in tension, which is the opposite of what would seem "normal". With the mast in compression, the top of the crossbar should be in compression too.

Is there a matching crack on the front of the crossbar? (I'm assuming it has propagated from the dolphin striker hole.)
Author:  srm [ Mon Dec 31, 2012 4:16 pm ]
Post subject:  Re: Done!!
Don't forget that the crossbars are also subject to high torsion loads as the bows try to go in opposite directions vertically. Add in material loss from galvanic corrosion and cyclical stress from a loose dolphin striker and you have your failure point.

There are at least four holes along the centerline of the H18 crossbar - the two dolphin striker holes and two mast step rivet holes. This equates to a lot of material removed from that area of the crossbar and particularly the top of the crossbar. The crack likely starts between the top dolphin striker holes and the fore/aft mast step rivet holes. It goes un-noticed until it propogates beyond the mast step.

sm
Author:  wscotterwin [ Mon Dec 31, 2012 6:40 pm ]
Post subject:  Re: Done!!
This is the pic after I got the post out. I think we had one good wave between us and a DNF.

This picture seems to highlight the corrosion, which actually doesn't look as bad as this picture, but you can see where the cracks probably started which plays to SRMs theory.

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Author:  John Lunn [ Wed Jan 02, 2013 12:55 pm ]
Post subject:  Re: Done!!
These pictures are excellent and timely....how many H18 sailors are in the middle of 'winter works' projects? This is a good time to repair and upgrade. I'm lookng at replacing shroud anchor pins, and all clevis pins. And one more thing...

I am buying a Hobie Tiger spin set up for my H18SX, and reading all of the above, I'm now concerned about drilling into the front cross bar to mount the spin pole....I have an idea to get around this 'focusing' of holes....which is to drill/rivet/mount an 18" piece of 1" or 3/4" square or round tubing on the front of the cross bar, and then attach the spin pole connector bracket to the tubing. In other words, the tubing would act as a spacer with its holes 9" outside of the centreline of the cross bar.

SRM or Matt M or Caleb (and others), could you email me off line at 'lunnjohn at magma dot ca' ?
I value your insights on this....I can draw out my square/round tubing idea and send you a PDF if that works.

Thanks and Happy 2013 to all.
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