Ok. A few boats do have a third halyard. If it were me, I would just use the two original sheaves. It's up to you.

-Jason 

:: Jason,
::
:: On Magic, the Jib halyard currently exits the mast below
:: the forestay pin. Above the forestay pin are two sheaves
:: that are occupied by the #1 spin halyard and the #2 spin
:: halyard. Should we remove the old #2 spin halyard and
:: use that for our jib halyard and not worry about the
:: "original sheave"?
::
:: :: Mike,
:: ::
:: :: Sounds like you still have the original sheaves in the
:: :: mast. You want to give Ballanger spars a call and have a
:: :: couple new ones sent to you. The original ones are for
:: :: wire halyards and will start eating up your nice
:: :: high-tech halyards.
:: ::
:: :: To answer your question though, you are probably going
:: :: to want to drop the mast to replace them. Both halyards
:: :: and the forestay ride on the same pin. So, to replace
:: :: the sheave you need to remove the shaft (pin) that goes
:: :: through both sheaves and the forestay eye. It can be
:: :: tricky to thread the needle through all three items with
:: :: the mast down, with the mast up would be very
:: :: interesting. I suppose it could be done if you held the
:: :: mast in place with the topping lift, but I would not
:: :: recommend it.
:: ::
:: :: One hint, when installing the new shives make sure you
:: :: use a small piece of line looped around the groove of
:: :: the sheave, as if it were a halyard running around the
:: :: sheave. If you don't you will likely drop the sheave
:: :: inside the mast and spend several hours trying to fish
:: :: it out of the mast. Ask me how I know this!
:: ::
:: :: Cheers,
::
:: :: Jason
:: ::
:: :: :: Our jib halyard sheave is very hard to turn. The sheave
:: :: :: appears to be intact, but is showing metal fillings on
:: :: :: both side as if it is not seated properly, although it
:: :: :: looks square to the mast top halyard entrance. How do I
:: :: :: take it apart to replace it? DO I need to drop the
:: :: :: Mast???
:: :: ::
:: :: :: Mike
:: ::
:: :: :: #80
:: ::
:: :: :: Magic