You need to look at the halyard sheaves to know how they'll feel to a
synthetic halyard. Further, i think it'd be a good idea to look for places
where a synthetic halyard might get chafed. The standing rigging and
sheaves should be inspected, cleaned and lubed (depending on type) annually
anyway, so i'd recruit a couple of strong friends and drop the mast. If new
sheaves are needed, they're available.

Tim wrote:

Hello,
I recently bought a Space Sailer 22 (22 foot keelboat). At the moment
the main and jib halyards are wire with rope tails. The wire seems to
be in ok condition but the rope tails are really bad (destroyed by
sunlight and moisture). I am considering replacing these halyards with
Spectra.

My question is - If I replace these halyards with spectra will I need
to replace the blocks at the top of the mast?? Being an older boat it
may not be a bad idea to lower the mast and check it out but if it can
be avoided it would be good.

I am of the understanding that there are different types of block
(with grooves etc and made of different materials) that are used
depending of whether you are running wire or rope. Would it really
matter if I use a spectra halyard if the block was originally meant to
run wire?? or would it jam or wear too much?

Thanks,
Tim