Once arriving at her new home port at Mare Island Naval Shipyard in Vallejo, California, Parche received ocean engineering modifications.

[citation needed] In the book Blind Man's Bluff, it is claimed that Parche successfully tapped into Soviet underwater military communication cables in the Sea of Okhotsk as part of Operation Ivy Bells.

While missile fragments were indeed collected in large numbers, Parche's primary missions typically revolved around the setting and retrieving of wire taps placed on Soviet underwater communication cables.

[citation needed] From 1987 to 1991, Parche underwent an extended refueling overhaul at Mare Island Naval Shipyard during which she was modified for research and development work.

These additions included an extensive array of signals-intelligence-collecting antennas, electronic gear, and other navigational and ocean engineering equipment.

The overhaul also added many auxiliary navigational and maneuvering features, including both upward and forward-facing short-range sonars, and a suite of armored spotlights and closed-circuit television cameras for under-ice operations.