The propulsion turbine had to be very large to operate at such a low shaft speed, and required a complex warm-up and cooldown procedure.

Narwhal was fitted with a "turtleback" structure just forward of her rudder that may have been used for remote-controlled underwater vehicles, or for housing an experimental towed sonar array.

Little information about Narwhal's career is available, but it was eventful and included a very heavy deployment rate interrupted only by three overhauls (two involving reactor refueling).

[citation needed] Narwhal sustained minor damage on 22 September 1989 when Hurricane Hugo hit Charleston, South Carolina.

She was decommissioned and stricken from the Naval Vessel Register on 1 July 1999, and entered the Navy's Nuclear Powered Ship and Submarine Recycling Program (NPSSRP) in Bremerton, Washington on 1 October 2001.

Over the next five years, efforts were made to make Narwhal the centerpiece of a planned National Submarine Science Discovery Center (NSSDC) in Newport, Kentucky.

The nuclear reactor and propulsion equipment would be removed and replaced with a plug of the proper dimensions and shape, containing a theater and classroom.