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Old 08-02-2015, 21:46   #1
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Mast collar cracking around turning block pins

Has anyone had their mast collar crack around the turning block pins? I have a (new to me), 2004 J/109 #195 (iirc). The mast collar appears to be a cast metal like cast iron. The two cracked joints in question are, of course, the blocks for the main and jib halyard. Am I doing something wrong, or is this an expected maintenance item on a 11 year old boat?

Thanks,
John
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Old 09-02-2015, 18:00   #2
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Re: Mast collar cracking around turning block pins

J,
It's most likely your mast collar is anodized/cast aluminum. The loads imposed on the individual block shaft housings would have to be great to break/crack unless there was a specific point loading at the break during a traumatic event(s). I would check your alignment from the halyard exit plate holes on the mast to be certain they are in alignment with the mast blocks rather than at an aggressive angle. If you are not the original owner of the boat, the block base may have been broken when the stainless shaft of the block became corroded by galvanic corrosion in the collar and someone tried to force it to remove the block. This was done on my boat by the PO. Hope this has given you a couple of ideas. Good luck and good sailing.
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Old 10-02-2015, 10:51   #3
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Re: Mast collar cracking around turning block pins

If you haven't found this page/site yet J/Boat Anarchy - Sailing Anarchy Forums they may have a bit more in terms of boat specific, & in depth answers for you. On this, other things J-boat related, & high(er) performance wise.
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Old 10-02-2015, 11:01   #4
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Re: Mast collar cracking around turning block pins

From looking at the design. It looks like those cracks were inevitable. a design defect if you will. If those turning blocks lead back to cockpit halyard stoppers, then the loads aren't in line with the pins that stick up through the casting to attach the block. The load should be taken at an angle that bisects the 2 directions of travel, not vertically. A better design would have used eye bolts as close to the base as possible to distribute the load and a shackle to attache the block to the eye bolt.
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Old 23-02-2015, 10:32   #5
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Re: Mast collar cracking around turning block pins

Sparcraft makes a newer (circa mid-2000s) deck collar for the J/109 that accepts 14mm pins rather than the standard 12mm pins. It also looks like they've beefed up the collar area around the pins to make them more resistant to lateral movement. The newer collar has a rounded shape from the vertical pin housing down to the base. The older collar is squared off from vertical to horizontal.
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