Forward mast on the USS Fletcher DD-992 - a Spruance Class Destroyer. Got a chance to ride on her one last time before she was decommissioned in 2004.
I was stationed aboard and made two 6+ month deployments on Fletcher from 1982-1984.
One memorable adventure was when I had to repair the connector below that "smokestack" antenna (upper left yardarm in the photo). I had to hang suspended upside down and use a soldering iron to repair several broken wires on the connector. Fun fun fun.