Mast sheaves

[Swanrad2]

Afternoon,

The mast sheaves at the top of my mast have seized. One can be punched out, the other looks like it is embedded in the mast somehow. Before I do anything else I would like to try and free them in situ. I was thinking:

1. Boiling water (it might be just salt) and work with a loop of rope
2. Rock Ease
3. Heat gun

Thoughts/experiences?

Thanks in Advance.

 

[Seajet]

Any chance of a photo or fuller description please ?

 

[vyv_cox]

My Kemp mast has aluminium sheaves with nylon inserts. Over many years the nylon swelled due to absorption of water. I had to knock the pins out and ream the nylon a little. That was many years ago - they have been fine since.

 

[oldbilbo]

My Kemp masthead had aluminium sheaves, too, which had become stucked-up. I had to pass a loop of 10mm line, douse the area in PlusGas, wiggle with a lever/screwdriver, then heave. T'was corrosion. The channeled surfaces of the alu sheaves were pitted, so I've replaced them ( for now ) with some Selden e'plastic sheaves which have stainless bush-inserts.

With a fair wind, I'll not have to do that job again.....

 

[Swanrad2]

Any chance of a photo or fuller description please ?

To my eternal shame I anot remember the make of mast!

There are two Halyards that run through the top of the mast, they both run in over one set of sheaves and out over another (four 'wheels' in total). One set (the forward set) have an axle that could be knocked out as a last resort although I would rather free them in-situ. The aft set appears to have no accessible 'axle' there is a small stainless plate (about the size of an oval penny) held in with self tappers near this second set which I assume must be some kind of access plate.

The mast is down at the moment, so had the idea of running a few fills on my wife's Karcher cleaner through the thing before taking a hammer and drift to the axles.

 

[andygc]

The plate sounds the same as mine - it covers the end of the shaft and you should be able to get the shaft out if you take the plate off. Mind you, a picture would help. How is the other shaft secured? - split pins in the ends?

 

[Swanrad2]

The plate sounds the same as mine - it covers the end of the shaft and you should be able to get the shaft out if you take the plate off. Mind you, a picture would help. How is the other shaft secured? - split pins in the ends?

Exactly right - split pins.

I will be going again this weekend, will photograph then.

Thanks

 

[wklein]

Difficult to tell without knowing what mast you have. Knowing the age / make of the boat would help. If you do decide to replace them i would have some made in delrin. The ones available from mast manufacturers tend to be pretty average and expensive.

 

[haydude]

To my eternal shame I anot remember the make of mast!

There are two Halyards that run through the top of the mast, they both run in over one set of sheaves and out over another (four 'wheels' in total). One set (the forward set) have an axle that could be knocked out as a last resort although I would rather free them in-situ. The aft set appears to have no accessible 'axle' there is a small stainless plate (about the size of an oval penny) held in with self tappers near this second set which I assume must be some kind of access plate.

The mast is down at the moment, so had the idea of running a few fills on my wife's Karcher cleaner through the thing before taking a hammer and drift to the axles.

Sounds like the configuration of a Selden mast top.

 

[Swanrad2]

The sheaves were welded with a smashing mix of Aluminium Oxide and salt, they weren't for shifting. I broke the bond between the axle and the sheaves by knocking hell out of them with a round ended cold chisel in dimples hammered into the sheave. Once the sheaves were turning (albeit tightly) I could knock out the axle from the wrong side, having drilled a small hole in the mast. Again the right sized cold chisel helped. The sheaves themselves needed hammering out of the sheave box as well.

The nylon inserts in the sheaves were tight as well. I have caused some damage getting them out and am struggling to find 75mm diameter (3 inch) sheaves at a decent price, rather than refurbing the old aluminium ones. Anyone have any recommendations?

The final bit of the job is to have a couple of small stainless steel plates fabricated with small pins that hold the axles in place in the mast box. Then up it goes.