After breaking a main halyard and a jib halyard from which the cover had been stripped I have returned to halyards with covers. The weight saving aloft isn't worth the issues of chafe and UV damage to halyards without covers, in my opinion.

:: This particular failure would not apply to the spin or
:: jib halyards because it occurred due to rubbing on the
:: upper shroud through-bolt, which is above both of these
:: halyards in the mast. However you should measure where
:: your chafing is occurring on the spin halyard so you can
:: determine what is causing it (my main halyard chafe was
:: ~47" away from the shackle, which indicated it was
:: occurring inside the mast).
::
:: :: Did you take a picture? I have some chafing on spinnaker
:: :: halyard and plan to inspect it also.It would help to
:: :: know what it supposed to look like.
:: ::
:: :: :: FYI. Our main halyard has been chafing in the mast so we
:: :: :: pulled the mast today and discovered that the halyard
:: :: :: was led on the wrong side (forward) of the through-bolt
:: :: :: for the upper (rod) shroud ends. Even worse, the boat
:: :: :: must have had a wire halyard earlier with the same
:: :: :: problem, because the through-bolt was "sawn" halfway
:: :: :: through! Luckily we caught it before the rig failed.
:: :: :: Lesson-learned.