Main Halyard Sheave?

[Ed Sitver]

Has anybody replaced the masthead sheave for the main halyard on a J/42 carbon Hall Spars mast?  Mine's adding drag to the system and I’m thinking I’ll wind up replacing it, rather than just adding grease.

I think I’m just going to have to pull it out and figure out what’s in there, but thought I’d see if anyone has found a replacement or encountered any issue with that job. Should be simple. Famous last words...

Ed

[David Jade]

FYI, if you don’t find a readymade replacement, there is this place in Port Townsend, WA which is well respected for making custom sheaves.

 

https://www.zephyrwerks.com/

 

David             _/)

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[Robert Kowalski]

On my boat I found I couldn’t rise the main without grinding, which was totally unacceptable, and taking it down would have to go up to the mast and give it a bunch of yanks. The pin for the sheave is just pined in so, I popped it out, it’s like a 5/8” pin. I got some sealed stainless bearings bored the sheave out, and pressed the bearings in. Worked okay but still found it a but more friction than I like so, the block at the bottom I took the sheave out and did the same I also butcher wax the track for slides. Now I can rise the main to about 2’ to the head without the help of a winch.

But the coolest part is sailing into an anchorage swinging her into the wind hitting the button for the anchor casually walk up to the companionway blow the clutch and with a whiz, and a thunderous thud it comes flaking down. And, yes I do take a bow…

You do have to keep up on it though, the bearings only last like five years and the track if your in year round you have to wax every six months but I do that when I grease the fittings on the rod rigging.

Bob

Sailing a course less traveled
Delightfully typed on a full keyboard on a mac

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[Mark Wensell]

I second Zephyrwerks - I replaced all sheaves on my J92s with his product and the quality was great.   Way better than the original.    

All four sheaves on the 92s were the same so I shipped him one to duplicate.   The first was lost in the mail by UPS(!) but fortunately had another spare to send.

[Larry Romano]

Harken sells Delrin sheaves with side ball bearings in various sizes. I found sheaves that matched my J40 exactly.

On Mar 24, 2025, at 7:33 AM, Mark Wensell <mark.w...@gmail.com> wrote:

I second Zephyrwerks - I replaced all sheaves on my J92s with his product and the quality was great.   Way better than the original.    

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[Sean Motta]

I do NOT have the carbon stick, but these were the dimensions I came up with when having all the sheaves in my aluminum mast replaced as custom Delrin pieces. Hopefully they help someone. They’ve been in for 3 years working flawlessly. About $180 delivered for all. 

Be careful using roller bearings for halyards and maintain long stretches under tension - you can deform a few of the balls and get a rough spot. They’re great for spin halyards or other more frequently moved blocks. 

Sean Motta

USA 52910

J/42 Hull # 50

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[Sean Motta]

And then it was too big to send…

Sending just the dimensions and one example image. 

Sean Motta

USA 52910

J/42 Hull # 50

On Mon, Mar 24, 2025 at 08:08 Sean Motta <sean...@gmail.com> wrote:

Finger hit the send a bit too fast. Sorry! Images attached now. 

Sean Motta

USA 52910

J/42 Hull # 50

[Ed S]

Great info all. Thanks!

I’m going to give Zephyrworks a try. 

Ed

------------------------------------
Ed Sitver
esi...@gmail.com
WhatsApp:  +1 303-570-5071
Mobile: +1 303-570-5071
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On Mar 24, 2025, at 08:09, Sean Motta <sean...@gmail.com> wrote:

And then it was too big to send…

<IMG_3660.jpeg>

<IMG_3658.jpeg>

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[S/V Sweet Ruca]

These guys may be able to source any sheaves you need. They were able to get us one for our J/46 quickly, even though the exact part wasn't on their website.

https://www.schaefermarine.com/

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[Ed Sitver]

So... here’s an oddball sheave question... 

The lower, smaller Genoa sheave that I’ve removed has an unusually shallow groove (1/16” when it would be closer to 3/16 for 7/16 line). Is it possible that's by design? I’m wondering if a shallow groove is more gentle on a pole topping lift exiting the mast at a sharp angle, as it often does when the pole is holding the genoa out. Or maybe the smaller diameter just won’t allow for a deeper groove. 

Am I overthinking this?  I have an order in with Zephyrworks, and need to sort out the depth of groove I want to specify. 

Ed

[Wayne Cassady]

Originally for wire to rope halyard?

Sent from my iPhone

On Mar 29, 2025, at 8:14 PM, Ed Sitver <esi...@gmail.com> wrote:

So... here’s an oddball sheave question... 

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[Mike Arntz]

I have a different issue regarding my main halyard sheave.  The "axle pin" separated from the small plate that screws onto the mast and began protruding out of the starboard side of the mast.  Surprisingly, the sheave seems to be spinning freely and in good shape. Fortunately, we caught this very early on a routine inspection and were able to rig a temporary fix.  Does anyone know where I can source a new axle/pin assembly?  Were you able to replace your sheave without removing the mast head cap plate?

[Mike Arntz]

Hello J4x owners.  I am commenting back on this thread as I have a different issue with our main halyard sheave.  During a routine inspection, we noticed that the pin/axle was starting to push out on the starboard side.  Apparently, the weld on the port side cap separated from the pin.  Surprisingly, the sheave still appears to be spinning freely and in good shape.  I think we caught it very early.  We built a makeshift solution and it's been performing but I need to fix it properly and probably replace the sheave.  Has anyone else had this happen?  Does anyone know where I can source a new pin/cap assembly?  Those of you who replaced yours - did you have to take the masthead cap off or were you somehow able to get the new sheave aligned and the pin/axle inserted?

On Saturday, March 29, 2025 at 4:24:43 PM UTC-10 Wayne Cassady wrote:

[Ed S]

Are you positive it’s a weld? Mine are screwed on.

Regards,

Ed

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Ed Sitver

esi...@gmail.com

WhatsApp:  +1 303-570-5071
Mobile: +1 303-570-5071

On Apr 3, 2026, at 18:30, Mike Arntz <michaelj...@gmail.com> wrote:

Zephyrworks

[Mike Arntz]

I haven’t taken mine completely off yet but I am pretty sure the pin is welded onto that cap, which is then screwed into the mast. 

This is a picture from an earlier post someone made.

Sent from my iPhone

On Apr 3, 2026, at 2:21 PM, Ed S <esi...@gmail.com> wrote:

Are you positive it’s a weld? Mine are screwed on.

<image.png>

Regards,

Ed

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Ed Sitver

esi...@gmail.com

WhatsApp:  +1 303-570-5071
Mobile: +1 303-570-5071

On Apr 3, 2026, at 18:30, Mike Arntz <michaelj...@gmail.com> wrote:

Zephyrworks

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[Larry Romano]

The pins are tack welded to the cover plate and the plate has a screw to hold it in place. When you remove the screw and slide the pin out, make sure you have something around sheave to remove it so it doesn’t disappear into the mast. There maybe a small hole on the other side of the mast to push the pin out. I found Harken sold delrin sheaves that were the same size as the metal sheaves. I’m talking J40.

Larry 

On Apr 3, 2026, at 11:42 PM, Mike Arntz <michaelj...@gmail.com> wrote:

I haven’t taken mine completely off yet but I am pretty sure the pin is welded onto that cap, which is then screwed into the mast. 

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[ArntzFamily]

Has anyone else had the tack weld between the pin and the cover plate fail?  Our sheave seems to be in good condition and spinning freely so I am still unclear as to why the tack weld failed.  I guess it could just be 30 years of sailing.  I should have mentioned that we have the carbon mast - not sure if that changes anything regarding the pin/cover plate assembly.

Mike

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[Dennis Boyd]

Hi All, 

We are continuing our refit.  I found this week that I too have busted weld on the main halyard sheave pin/cover plate.   Sharing photo's for folks to see.   Sheave seems to be ok.    This is on our Aluminum mast

I was planning just seeing I can get this rewelded.      I am conflicted, as I am really trying to pull everything back together.    I going to speak to the yard.    We just got the mast repaired  waiting to replace all the standing rigging, but we got this one more thing.....

Dennis

J/42 #6 

Jaywalker