Change halyard sheeve at mast top, how?

[ohthetrees]

I'm in Colombia, so I'm looking for some DIY advice.



Hello, I have a Hanse 505 with a selden mast and rig, and I'm pretty sure the main halyard sheave needs to be replaced. It is wobbling, and turns with a big eccentricity, and gets stuck, so the halyard just slides over the sheave instead of the sheave rotating.



Anyway, I'm wondering what the usual technique for getting this sheave changed. Can it be done at the mast top? Or do I have to remove all the electrical equipment from the top of mast, and remove the whole mast head assembly and bring it down? I've googled but I don't think I'm using the right search terms.


Any advice is appreciated!

[marcjsmith]

looks like you can flip the instruments out of the way to gain access to the sheaves. provided you have enough cord length down side is that you'll be aloft on the genoa and spin halyards while trying to work on the main/topping lift sheaves.

the instrument base on selden is referred to as a headbox


can stress enough to be very careful and make sure you are secured proper.


figure while you are up there with everything apart might as replace the forward sheaves as well..


found this tidbit
https://www.myhanse.com/replacing-a-...351_page2.html

[neilpride]

Fractional rig?? First , you need to rig a temporary backstay out of the masthead, could be along the top cap shrouds , rig 2 halyards from the top cap shrouds to each side of the stern, if you have a couple of strong cleats, better.

Then you need to slack all the DC wiring from the mast base , vhf, lights, wind instr etc...

Then slack the 2 bolts at the front of the masthead, with luck, with this 2 bolts loose maybe you will be able to slide the masthead backward a bit and reveal the pin.

If not ,then you would need to loosen the bolts completely and slide the masthead up to gain access to the sheaves pin.

In any case , you cant count with the main halyard or toping lift to climb up there??

[neilpride]

Yep , i only see left side of the mast, what about the right side, any pin there?

[markxengineerin]

That seems like a (really) tough job to do at the top of the mast. On my boat, I struggled for a few minutes to get the pins, pulleys, and halyards lined up even with the mast down and on its side. I can't imagine doing the same thing up there and working against gravity.

[marcjsmith]

the pdf from selden shows a pretty good cutaway. like it was designed to have the sheaves replaced while the stick is up. if his mast headbox is the same. won't be easy or comfortable. but dare i say easier than taking the rig down.


7/8ths fractional if hes got a spin halyard that's what he's going up on.


or go up on the topping lift with main as back up, and then tie off on the backstay attachment with spin as back up and then slack the main and topping to take pressure off the sheaves...


won't be easy or comfortable. but dare i say easier than taking the rig down.

[neilpride]

501-082 cant found any info or pdf, should be the same headbox system.

[marcjsmith]

Originally Posted by neilpride

501-082 cant found any info or pdf, should be the same headbox system.

i could not find any info on the stamped number either, but the selden website for the headbox pdf is attached in my first response.


if its the same or similar to whats pictured he's gotta chance.


Id pull the instrument plate off and take a gander. hopefully you have an electric winch to go up and down. otherwise the foredeck and trimmers union will go on strike.

[capt jgw]

As always, doing any mast work is so much quicker and easier with the mast on the ground. Not to mention safer, I hate going aloft. If there's any way to unstep where you are, I'd do that.

[Pandor]

Yikes, 2nd photo looks to show a missing cotter pin in the backstay clevis pin (just adjacent to Wndex attachment nut). And did a low bridge do that to your Windex support rod?

[Chotu]

Definitely yikes!

[marcjsmith]

Originally Posted by Pandor

Yikes, 2nd photo looks to show a missing cotter pin in the backstay clevis pin

nice catch

[ohthetrees]

Lots of great stuff here, thanks for finding that PDF. After looking at it I, I think I can do it up the mast.

Don’t worry ladies and gentlemen about the clevus pin, I dropped the back stay for another purpose here at the dock, the mast is stayed by two running backs days at the moment.

Thanks again all!

[ohthetrees]

Thanks for everyone's help! I have retrieved the broken sheave. Now I'm trying to purchase replacement parts. I could buy the exact same part from Selden, but I'm wondering if there might be a, aluminum or stainless option that would be stronger.


The sheave I have is:
https://support.seldenmast.com/en/pr...1&item=504-337


90mm diameter, 16mm wide, 16mm hole.


Is anyone aware of an "upgrade"? I found some very expensive Harken parts, but I think they must be a USA company because they do inch sizes, and their high load sheaves are too big or too small.


I'm also wondering if anyone knows the part# (or how to find it) of the pin/axel. It seems to be aluminum (it is pretty light weight) and is 16mm diameter and about 49.3mm long. Unlike most Selden parts it doesn't have a part number stamped on it. The one I have is a bit worn, and I'd like to replace it.

[AiniA]

I had some sheaves made by these guys - good quality and decent price. They work with different materials.

https://www.zephyrwerks.com/masthead-sheaves