J/30 Class Association Forums J/30 Forum The Boat, Sails and Equipment Replacing spin halyard sheave

Forestay length cannot change so your rig tune will have to be adjusted for the 1 inch difference. You will have a tighter headstay - basically.

You could probably get longer shaft with threads on the bottom of the forestay turnbuckle to bring the headstay back to max class legal length.

Oops - just reread this - never mind. I agree with David Bows. The attachment point on the mast changes, not the headstay length.

Correct you will have to tighten the head stay with the replacement box
I've had mine out drilled out the rivets replaced the shives with replacements from Hall and used roll pins to replace them
It was an easy job with the mast out of the boat I have in the past taken it out with the rig up not easy but possible You have to rig a tempory forestay to support the rig

The site says explicitly: the forestay length will change accordingly.

Charlie,

How did you go about pulling the jib box with the mast up? I'd like to try this. How much tension did you put on you're replacement forestay? What precautions did you take before going up the rig?

Also-the reduction in weight that high up would seem to be a significant performance enhancement. Is it class legal?

Just a thought-if you have to lengthen the slot in the mast to accept the new box, why not lengthen it an extra inch and install the box low, so the pin ends up in its original location?

I think if you did that, you'd loose that inch in all you're hoist heights.

Oops-good point. I wonder why the pin location had to move. Is it possible that the sheaves also are higher?

Just a note to let everyone know that I spoke with the class measurer who is getting data on the related parts, and mechanical parameters from the class approved mast suppliers. Once this data is available he will post information in the OD Class Rules forum.

They also have a sheave replacement pack: http://rigrite.com/Spars/Kenyon_Spars/4060-MORC.html part K-10658SK. It is $199. It has the sheaves and bushings you need, but if you drill out the old sheaves, you'll also have to replace the clevis pins (7 total). Not sure how long they have to be. If anybody knows, I'd like to know too.