Belize 43 - Main sail Sheave in mast head

[Claireee]

Hi,
Is the main sail sheave pin that locates at the top of the mast an interference fit. Our sheave has shattered and needs to be replaced. Any information on exact mast model (Z-Spar) sheave size (some of the shattered pieces are missing) and pin removal / relocation tips welcomed.
TIA
Claire

[belizesailor]

Yes, its just an interface fit.

I dont have the specific dimensions, but a few related suggestions. Someone here likely has the specific dimensions.

- save the sheave pieces so you can confirm size. You will need diameter, thickness, and channel size (see diagrams readily available online)

- pin removal is usually easy unless corroded. Typically there is a retaining scew or cap. Once that is removed, you just push the pin out via the access hole on rhe other side of the mast.

- most production builders use acetal sheaves because they are inexpensive and will last beyond the warranty period. Downsides are that UV degrades them and they are brittle (even when new they can crack). At the least upgrade to derilin which is much stronger and impervious to UV.

- TefGel the pin and other stainless fittings where they contact the mast to prevent corrossion.

While you are up there is a good time to check the mast head for other maintenance issues.

If you really want to do it right then order custom sheaves from Zephyr Werks (no affiliation, just a happy customer]. They can make you derilin sheaves with silicone bronze bushings. Dramatically more expensive but will last a lifetime and give you confidence that they wont fail when the going gets tough (which of course is exactly when acetal sheaves usually fail).

https://www.zephyrwerks.com/

[Claireee]

Thank you for your comprehensive reply, much appreciated