Replacing Mainsail Halyard Sheave

[36900]

Has anyone replaced their mainsail halyard sheave? I am trying to figure out if the sheave can be replace without removing the masthead.

[Vento Solare]

I'll let you know next week. My mast is off awaiting a replacement from storm damage and I'll check out the sheave at the yard when I'm there.

[Mvallus]

Never replaced the main sheave but pretty sure the last time I had the mast down for VHF maintenance it can be done through simply and very carefully removing the clevis pin. Mine is a newer mast though, so unsure if there are slight design differences (shouldn't be). There is a handy manual from Charleston Spar (in the manual section) that should should show this is removable. Bill can confirm (sorry to hear about that storm damage, Bill).

[Dan Corcoran]

Yes, I replaced them all last year while they were laying flat either by removing cotter pins or in one case I think there was a little metal door that screws off/on.

It is a little difficult removing the sheave. We lost a sheave in the mast, where it stays to this day.

The only prep, is to replace the halyards with tracers before you get started, not sure if that was necessary but it is a good idea to not have to deal with the lines.

[Dan Corcoran]

While you are at it, a good upgrade is to install a plastic VHF antenna mount and a small 3 inch extension, to which you mount the anchor light.

Place the anchor light as far to the rear as you can.

Then replace the bulb with one of those Marine Beam bulbs that can be toggled into a navigation light.

Why do this?
1. Raising the fixture makes it easier to see from the deck that you successfully toggled into navigation mode
2. Moving it back away from the wind sensor pole makes it more visible / less blocked by the wind sensor pole
3. If someday you make the effort, you can rig up some basic electrics in your DC panel for a spare battery and meet the full regs for a second independent powered Nav light. Either spend some dough and setup a rechargeable battery and on/off switch, or rig up some simple wiring to clip in a bank of 8 disposable C cell batteries. Ideally you include a diode in the circuit so the C cells are only powering the masthead light. No switch necessary. Plug in the batteries only in emergency. Keep the 2nd battery holder in your emergency kit in case batteries leak after never using them.

[Dan Corcoran]

Anchor light / Nav light combination using 2 wires.
https://store.marinebeam.com/led-tri-co ... tion-bulb/

[Dan Corcoran]

I have a used one for sale, $30 + shipping (normally $89)
Single bayonet version

[36900]

Folks,
Thank you for your responses. Very useful.
I am trying to decide if the mainsail halyard sheave can be replaced while the mast is installed. The yard has a crane that will reach the sheave, but it may be too complicated to perform the replacement while the mast is installed. Any thoughts?

[Vento Solare]

It can be done with the mast up. Always easier with the mast down, but no need to go through that expense if there is no other reason to drop the rig.

[36900]

Bill, Et Al.
Thanks for your input. I now believe that I can use a crane to replace the sheave while the mast is up. Thanks again.