# changing sheaves on masthead problem



## dancamp (Aug 20, 2007)

I've just lowered my mast to change the halyards from wire to rope and have found a problem. There doesn't seem to be enough room within the mast head to change the wire sheaves to rope sheaves and the mast head is welded to the mast and cannot be changed. Is there anyway to work around this problem to allow me to change sheaves to rope size? Here are some pictures of the mast head. I didn't measure the sheave size and space available, but I would guess the size total inside that area to me no more than 1/2" max, and maybe even 3/8" which would mean a serious alteration. 
thanks again for any help.


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## btrayfors (Aug 25, 2006)

You need to consult a rigger. But it looks very much to me like if you're really intent on replacing the wire halyards with rope, you're gonna have to have a new fitting built to replace the old one. Counting materials, fabrication, welding, etc., that's likely to be very costly.

Bill


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## dancamp (Aug 20, 2007)

thanks Bill. Looks like I'm sticking with wire halyards. Now I need to figure out how to prevent them from destroying my mast around the head area while it's sailing. Any suggestions?


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## Stillraining (Jan 11, 2008)

So whats your reason for wanting to change it?

My Mizzen is still a wire to rope spliced halyard and I have no intentions of changing it cause it works just fine...rope for your hands and winch and wire beyond...even if you replaced your halyard every other year which you dont need to do..the cost is minimal... Less wind-age aloft and not that much heavier either.


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## sailingdog (Mar 19, 2006)

Replacing the sheaves on that masthead should be rather simple, provided the mast head sheave slots are wide enough for the replacement sheaves. The two shafts with the cotter pins are sheave axles, and if you remove them, the sheaves should drop out. 

You don't say what kind of boat it is, but if it is less than 40' you can probably get away with 8-10mm t-900 line for the halyards.


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## dancamp (Aug 20, 2007)

I was happy with half wire halyards too until they stretched out and started wrapping around the winches and chewing them up. After climbing the halyards they stretched out even further so i cut them back (too much) and now they need to be replaced, which is fine with me. Have you checked your mast for damage on top lately? I wonder why mine is getting so chewed up? Something is wrong and I need to stop the destruction before it wears a hole into the mast or worse yet the mast breaks off at the top.


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## Stillraining (Jan 11, 2008)

Dan:

Yes I just Striped and repainted my masts...there was zero dammage you refer to....Something looks screwy in your picture...I have added a diagram...It looks as if by the way your shives are positioned that they were designed to be internally lead but appear to be externally lead???? ( two lines at red arrows ) if they are they are taking one heck of a turn at the mast head and no wonder your getting dammage.


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## sailingdog (Mar 19, 2006)

I don't see why you can't change out the masthead sheaves for ones that can accommodate rope. Without a better photo that gives some idea of size, it certainly looks like the sheaves could be swapped out by pulling the axle pins, which are clearly seen in the third photo. The slots look to be at least 1/2" wide. 10mm T-900 would fit on a sheave that fit in that slot, and has a breaking load of 11,600 lbs or so—more than strong enough for any halyard you'd need more likely than not.


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## sailaway21 (Sep 4, 2006)

Those don't appear to be the pins for the sheaves that Rainy has circled and Dog refers to. From the first photo it appears that the sheaves are much larger diameter, there is one per halyard, and their pins are captured inside the mast. Cutting torch job, and that's the easy part!

Parcel and serve the offending rigging.


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## dancamp (Aug 20, 2007)

yes they are externally lead halyards that run from the front to the back and vise versa for the other. And I doubt there is enough room to fit rope sheaves inside there. I'll give it a try though it will have to be pretty thin rope. It's only a 30' sailboat, so it shouldn't take too thick of rope, but considering the size I think I'm in trouble. Tommarrow I state the exact space available and what my options are.
thanks again to all


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## dancamp (Aug 20, 2007)

and yes those are the pins for the sheaves like Rainy guessed they were. there are two sets of sheaves (two for each halyard).


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## Stillraining (Jan 11, 2008)

Then I was wrong with the rigging and they are rigged like this...other then Dogs suggestion the only other fix would be to move the shives say a 1/2" for and aft as depicted by the red dots to get clearance away from the mast...Dogs solution may be easer *BUT* if you have a chafing problum with rope...it wont be the mast wearing out...And you may end up moving the shives anyway to keep from parting halyards continuously..


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## Stillraining (Jan 11, 2008)

One other option if you have room is a 1" diameter larger shiv as this would give you the same 1/2" clearance from the mast with out repositioning the shiv.


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## knothead (Apr 9, 2003)

One possibility is to remove the sheaves and the divider. Then install a single sheave forward and one aft. Using only one it should be easy to find a sheave wide enough to accommodate whatever size line you desire. 
Of course you will have to change over to internal halyards and cut a couple of exits. 
By the way, your headstay doesn't appear to be toggled at the top. It should be.


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## jbondy (Mar 28, 2001)

FWIW - An alternate solution: my rigger made a compound halyard of two different rope sizes, basically the same as the wire/rope halyard only using a smaller diameter rope to replace the wire. The smaller rope works fine with the wire sheave. It has the advantage od less windage and weight aloft and you don't have to do all this mastehad work.


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## menado (Jul 17, 2008)

Looks like the sheaves are too small that the wire hallhards were too close or rubbing to the mast both in and out. replace with larger diameter sheaves.


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## JohnBoelte (Jul 4, 2008)

It looks to me like the mashead is intended to have the halyards run inside the mast. Is there any way to reconfigure your mast and halyards to run inside?

I just replaced all of my halyards; they run inside the mast. A couple of differences between our situations: My mast is only 27'; and, the masthead is fastened with screws, not welded. Good luck!!


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## dancamp (Aug 20, 2007)

yep, looks like I don't have enough room in the mast head to change to bigger sheaves big enough for 3/8" line, so I've got to stay with wire-2-rope halyards or use 1/4 in. line, which doesn't seem to be strong enough for a 30' boat main and jib halyard.
thanks for all the help guys.


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## sailingdog (Mar 19, 2006)

Dan-

6mm T900 has a breaking load of 4400 lbs, the same as most 3/8" polyester double braids. You could switch to that and if you want the line a bit thicker to handle easily, you could have a cover attached to the bottom end of the halyard.

6 mm or 1/4" 7x19 316 stainless wire has about the same breaking load as 6mm T-900.


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## dancamp (Aug 20, 2007)

hey, that sounds like a good idea saildog and certainly the simplest sollution. Thanks for the advice, I'll look for some of that T-900 today locally or online.
thanks again.


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## dancamp (Aug 20, 2007)

one more question Saildog? what do you mean by "attatching a cover to the bottom end of the halyard" to beef it up? What sort of cover? 
thanks again


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## jbondy (Mar 28, 2001)

sailingdog said:


> Dan-
> 
> 6mm T900 has a breaking load of 4400 lbs, the same as most 3/8" polyester double braids. You could switch to that and if you want the line a bit thicker to handle easily, you could have a cover attached to the bottom end of the halyard.
> 
> 6 mm or 1/4" 7x19 316 stainless wire has about the same breaking load as 6mm T-900.


That's the compound rope halyard I suggested above! Works great.


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## sailingdog (Mar 19, 2006)

Basically, they'll be covering the bottom portion of the rope with a polyester braid, similar to the outer layer of a normal polyester double braid line. This makes the line effectively thicker—allowing it to be used in line clutches for larger diameter lines as well as making it easier on the hands.


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## dancamp (Aug 20, 2007)

thanks again. 
where can I buy this braided covering?
thanx


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## KeelHaulin (Mar 7, 2006)

Or you could go with 8mm (or possibly 10mm) and strip off the cover where the wire previously ran. So you would have a standard core/cover halyard at the winch but then just the core where it goes aloft. That's a common practice for racing sailboats to minimize aloft weight while maintaining the strength of the halyard.

HTH...


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## sailingdog (Mar 19, 2006)

Yes, he could go with 10 mm and the core is probably only 6mm in diameter.


KeelHaulin said:


> Or you could go with 8mm (or possibly 10mm) and strip off the cover where the wire previously ran. So you would have a standard core/cover halyard at the winch but then just the core where it goes aloft. That's a common practice for racing sailboats to minimize aloft weight while maintaining the strength of the halyard.
> 
> HTH...


Many riggers carry this type of product, especially if they cater to the racing crowd.



dancamp said:


> thanks again.
> where can I buy this braided covering?
> thanx


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## dancamp (Aug 20, 2007)

Okay, my final solution is to buy 1/4 in. T-900 for my halyards (which fit perfectly inside the sheaves) and add a double braided wrapping at the ends for tying them off. 
Once again, I deeply appreciate all the help that came from this wonderful forum. Hope this sort of help never ends.


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## rocinante33 (Dec 4, 2007)

Another factor here that hasn't been mentioned is that the sheaves may have burrs or grooves from years of wire halyard chafe. I think you should pull the sheaves out.... they need to be serviced anyway. A local machine shop can turn those sheaves for a very nominal fee. It would be a simple job for them. They can remove any burrs and also expand the grove to fit your new all-line halyard. When done machining, you can grease it up before reassembly and it will work better than new with the halyard led internally.


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## dancamp (Aug 20, 2007)

thanks rocinante33
I should have mentioned that I eventually did remove the sheaves and filed them all down smooth to remove any burrs that were there. Put it all back together and added the T-900 1/4" line and it is all working fine now.
thanks again guys
dancamp009


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## sailingdog (Mar 19, 2006)

Thanks for updating us...


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## smackdaddy (Aug 13, 2008)

Guys - I'm about to replace a couple of broken masthead sheaves. Should I lubricate the old ones? And if so, what should I use?


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## menado (Jul 17, 2008)

If the sheaves and shaft are broken, I would replace them. If the sheaves are sleeve bearing I would put some grease in the shaft bearing, but if they are roller bearings, the oil will absorbs dust and increase frictions. The manufacture will have some info about maintenance.


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## CalebD (Jan 11, 2008)

McMaster-Carr has a nice selection of stock 'pulleys' or sheaves: McMaster-Carr


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## knothead (Apr 9, 2003)

smackdaddy said:


> Guys - I'm about to replace a couple of broken masthead sheaves. Should I lubricate the old ones? And if so, what should I use?


In my opinion, you should take every opportunity that presents itself to lubricate masthead sheaves. Actually, what you use probably depends a lot on how often they are lubed. Some things I lube with spit. 

But in all seriousness, I am partial to Teflon spray greases for things like that. They go on as a spray and penetrate pretty good but then gel up and and stay put. If the sheave is really squealing, I would probably use something like WD 40 or a penetrant first to shut it up and then try to get something more greasy in there. If you are taking all the sheaves off the sheave pin, then use some Never-seize on it before you put it back in the aluminum.
You don't say whether or not you have the mast down so I'm assuming that you are doing all this from a chair. That's why I suggest the sprays. If the mast is down, it's a whole different thing.


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## sailingdog (Mar 19, 2006)

If you're replacing a couple, you should probably replace all of them, since the ones that failed are probably the same age as the ones that are left. Chances are very likely if you don't replace them all, the remaining ones will fail shortly.

Be aware that some sheaves have low friction bearings, like the ones made of torlon, and that lubricating them is not recommended.



smackdaddy said:


> Guys - I'm about to replace a couple of broken masthead sheaves. Should I lubricate the old ones? And if so, what should I use?


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## smackdaddy (Aug 13, 2008)

I'm replacing 2 of the 4. And they are sleeve bearing. The other 2 are metal and seem to be newer. I'll check to see if they have bearings.

Thanks dudes.


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## knothead (Apr 9, 2003)

sailingdog said:


> Be aware that some sheaves have low friction bearings, like the ones made of torlon, and that lubricating them is not recommended.


Gimme a break. There is no way you are going to cause a problem if you lubricate your masthead sheaves. Even if they are made of Torlon.


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## sailingdog (Mar 19, 2006)

BTW, McLube has a new lubricant specifically designed for sheaves and such... that is a dry film, long-lasting lubricant.


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## smackdaddy (Aug 13, 2008)

Cool. Thanks Knot. So what do you recommend I use? If anything. My main sheave is metal and is a tad squeaky - but I don't know if it's on a bearing or not.


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## knothead (Apr 9, 2003)

Teflon Grease


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## smackdaddy (Aug 13, 2008)

Thanks dude. That's all I need.


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## therondor (Mar 6, 2010)

the halyards in your picture are supposed to be external that is why there are four sheaves in the head not two.


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## therondor (Mar 6, 2010)

the halyards in your picture are supposed to be external that is why there are four sheaves in the head not two.if you look down from the top you will see that there 2 sheaves per axel, giving you a sheave for and a sheave aft for each halyard.


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## therondor (Mar 6, 2010)

i cannot see if the cable is wearing into the mastop at all from your pictures if the sheaves are worn to small the abrasion would above and in the welds if so larger ordiameter of new replacement sheaves is your best choice


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