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[E35-3] Masthead Sheave Removal

Hagar2sail

Member III
Blogs Author
I have read through a few people’s threads on here and everyone seems to have a “Kenyon” (sp?) spar. The masthead pictured always seems to have a large welded assembly at the top. Our 35-3 seems to have a different setup. I am looking to try and remove the sheaves so I can check their condition and measure the axel diameter for possible replacement. Our main halyard does not want to run freely and part of the issue I believe is its sheave.

Looking at the mast, I am guessing I just back out the slotted screw then the idea is that you can just pull (up in this case) removing the axel and allowing the sheave to come out, assuming that corrosion hasn’t caused everything to seize together. The opposite of the mast picture below is smooth (no holes), so this looks like a one sided affair. Do I have this right?

Second question is, it looks like the fasteners might have been put in with some kind of semi-clear rubber like sealant. Maybe this is to prevent them from backing out? If I remove these do people have a recommendation as to what I should use when putting them back in? It can be seen coming out under the leftmost screw head and is also on all of the cotter pins holding the furler hardware together.
 

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bgary

Advanced Beginner
Blogs Author
That actually looks like a pretty typical mid-80s Kenyon masthead.

those oblong plates are welded to the ends of the axles... and the axles only come out one direction. You unscrew the fastener and pull the plate, the axle comes out with it.

which means... don't pull the plate until/unless you're ready for the sheave to come free. If you pull the axle, the sheave can/will drop into the "sheave box" and be a major pain to get out.

What I did - I had the mast out of the boat, which makes it easier - is loop a piece of "tag-line around each sheave, snug it up into the groove so it can't come off the sheave, and tie the tail to something so that, no matter what, I can retrieve the sheave and maneuver it around - either out of the masthead for replacement, or back into position for putting the pin back in place.

From your picture, the left-most plate secures the axle for the main halyard,. the bottom right plate secures the axle for the center/jib halyard, and the top-right plate secures the axle for BOTH spinnaker halyards (yes, two sheaves on that one axle)

EDITED TO ADD: you will probably have to take the halyard-guard off the last in order to get the forward sheaves out of the mast. And you'll probably have to remove the headstay toggle to get the halyard-guard off. Neither is a big job, but... something to include in your planning.

When you have the sheaves out, good time to evaluate whether it's a good time to replace them. The old sheaves may be made for wire halyards, which may not still be applicable. They may be worn, and/or wobbly on their axles. I had a new set made by Zephyworks and am very happy with them.

When it's time to re-install them, I'd recommend some good quality waterproof grease on the bearing surfaces (I used a white-lithium grease).

For the fasteners, there are a couple of schools of thought for isolating the stainless fastener from the aluminum spar. TefGel is a teflon-based gel that stays soft, and is used a lot in these scenarios. LanaCote is more readily available but (IMO) not as good as TefGel. DuraLac (a little harder to find) is also a material that provides protection against galvanic issues, but it takes a "set" (semi-hardens over time) so that it acts a little bit like a thread-locker, too. For places where I have fasteners I'm not going to see/inspect very often, I prefer Duralac.

My masthead saga chronicled here: http://www.ericsonyachts.org/infoexchange/entry.php?402-Time-is-Fluid-**-(mast-re-hab-part-1-of-3)

Picture of the Kenyon axle-plate part (RigRite) here: http://rigrite.com/Spars/Kenyon_Spars/Kenyon_Parts/K_Sheave_Axle_Pin.php

(mine were 3/8" axles of various lengths. My guess is that your 35-III also uses 3/8" axles)

Bruce
 
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Hagar2sail

Member III
Blogs Author
Thanks!

I enjoyed reading your tale of a “couple of weeks” project. It was very informative. I actually think I had read it before but for some reason didn’t put 2 and 2 together. Good to know we do have a Kenyon spar. Also, thanks for the advice on the anti-corrosion compounds.

I hope my axels and cover plates have not become as one with the spar as yours had!

As usual I will post as my project develops.
 

Hagar2sail

Member III
Blogs Author
Well, I have the first and most important one off. My axel gloriously came out with little fuss, and the screw even gave me little challenge! The axel measures between .369 and .3705 depending on where I measure. The sheave bearing was approximately.3775, so not super sloppy but not super tight either. Now my wife and I are trying to decide if we should do all 3 (main, Genoa, spinnaker) or just the main, as that was the one that gave us a lot of trouble. Some of the issue was certainly the caked on old grease that was not providing any kind of lubrication, but we will take this opportunity to switch over to a rope sheave anyway. Question is really if the others are worth it. The boat projects are piling up and we are starting to bleed a few too many $100’s as is the story of all boats. Since we only raise the Genoa once a year that one would be motivated only by reducing line chafe. I would have to replace a Harken fitting as well, since that too seems to be meant for a wire.
 

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Christian Williams

E381 - Los Angeles
Senior Moderator
Blogs Author
Bruce--do the new sheaves make a difference when hoisting a sail?

It's pretty hard to tell, from the deck, whether a sheave is even turning turning up there....
 

bgary

Advanced Beginner
Blogs Author
Bruce--do the new sheaves make a difference when hoisting a sail?

I think so, in fact a pretty noticeable difference. the biggest difference (in my opinion) is not the sheave itself, but the fit on the axle. When the axle wears down and/or the hole in the sheave grows, it creates the potential that any off-axis load will allow the sheave to tilt on the axle and bind against the sides of the sheave box.

Might not be a big issue with jib-halyard or main halyard, both of which are normally relatively "straight" loads, but... hugely noticeable difference when using the wing halyards.

Full disclosure, there is a downside. When I replaced my sheaves, I went with the bronze bearing option, and the resistance is so low that, in a moment of inattention last spring, I lost my main halyard. Happily, at the dock, and easy enough to re-run, but... I had been fussing with the shackle end in the cockpit, I failed to secure the tail, the weight of the running end was apparently just enough to get it moving, and before I had a chance to say "oh, crap!" I watched the tail disappear into the mast. Kinda wish, for that one second, that my sheaves had had just a tad more rolling resistance...

Bruce
 

bgary

Advanced Beginner
Blogs Author
I would have to replace a Harken fitting as well, since that too seems to be meant for a wire.

I think, assuming there are no burrs or sharp edges, that harken fitting will be just fine for an all-rope halyard.

$.02
Bruce
 
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