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zenyatta

New Sheave Box - Going from wire to rope

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As I have my rig down I figured it would be a good time to get rid of my wire halyards. Of course it means I need a new sheave box for the Jib halyard.

I found the equivalent sheave box sized appropriately for rope halyard - it has the same length but is slightly wider. I am pondering how to approach the installation since the holes on the mast will be slightly misaligned with the new box. 

My current plan is to use a dremel with cutting blade to slightly widen the slot in the mast and then see how far off the holes are. I don't think it will be much. Fortunately the middle hole was unused with the previous sheave box so I will be able to drill two solid new holes for that. I plan on tapping the holes for new stainless machine screws. 

I am unsure about exactly how to approach the other two - my only decent idea so far is to widen / create a slot etc. on the new sheave box so that it aligns with holes already in the mast - this seems to me to be the best approach if they are only slightly off. But I'm curious if anyone out there has any better ideas.

Of course I could always just keep the wire - but if I can make this work I'd prefer to switch over to rope.

Thanks all

Chris 

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If you think there is enough 'meat' around the new fastener holes you are good to go. The rule is about a hole diameter is enough. If not you should fit an aluminum plate to carry the load out to additional rivets into the mast.

Make the cutout fit nice, perfect and tight so there is not much need for fasteners anyway. The forces on a headsail sheave are downwards and inwards, luckily.

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Use some Al pipe or tube to make curved backing plates that match the inside of the mast.  You can slip them in though the big hole!  Makes it so much easier.  Glue them in with thickened epoxy.  That will give you plenty of good metal for the screws.

You could slot the holes on the sheave box too, if they are close to lining up.

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