Old Halyard Sheaves

Do you own a sailboat that is older than about fifteen or sixteen years old?  When was the last time you inspected the halyard sheaves in the masthead casting?  There is a good chance that your boat's manufacturer used some sort of plastic or nylon for those halyard sheaves.  There also is a good chance that the sun's ultraviolet light has damaged those sheaves over the years.  The sunlight makes the plastic become brittle and the "shoulders" of the sheave break off - - ultimately, the sheaves won't hold the halyard anymore and the halyard slips off the wheel and becomes jammed between the side of the sheave and the masthead casting.  Raising (or more importantly lowering) the sails will be difficult if not impossible.  I postponed and rescheduled a private sailing lesson yesterday for just this reason - - the halyards simply were too difficult to operate.

Here is a photo of one of the original halyard sheaves from Snickerdoodle (on the right).  You can clearly see the damage to the shoulders of the wheel.  On the left is the new silicon/bronze sheave that I replaced the original sheave with.  Of course, I replaced all four sheaves.  Snickerdoodle was about 16 years old when I made this change.
So, if you haven't inspected your masthead sheaves recently, it is probably past time that you did.  Imagine what would happen if your were not able to douse your mainsail or a jib sail in an emergency situation......  BTW - the new silicon-bronze sheaves were machined for me by a friend with a metal lathe.  Cost for the materials and the labor was not that much more than the cost of four new plastic sheaves...... AND the metal sheaves won't be affected by sunlight.