Military

On 20 September 2000, a U.S. Navy submarine pulled slowly away from her berth in Norfolk, Virginia to begin the final voyage of her 25-year career. The solemn faces of the well-wishers gathered on the pier, many of whom had served aboard the "Usta-Fish" in years past, reflected the one thought on all of their minds - the USS L. Mendel Rivers (SSN-686) would be missed. The days ahead were sure to prove bittersweet for the crew, and the mood on the pier echoed that onboard the ship. This mission marked not only the final voyage of a great naval vessel, but also the eminent demise of an entire class. USS Sturgeon (SSN-637), which first entered service in 1967 and was decommissioned in 1994, would have only USS Parche (SSN-683) to carry on the legacy of her class once the Rivers was put to rest. But first, L. Mendel Rivers had things to do.

We were well prepared and eager to perform the task ahead, which at first glance appeared to be a simple one - proceed to the Arctic Circle and operate submerged beneath the polar ice cap for several weeks. Along for the ride was a team from the Arctic Submarine Laboratory, who hoped to profile ice thickness in shallow uncharted areas of the Arctic basin and launch a large number of probes to gather scientific data on the ocean's properties. When the scientific portion of our mission was complete, we were to transit the Bering Strait and proceed to the Puget Sound Naval Shipyard (PSNS) at Bremerton, Washington for final deactivation. Our mission sounded straightforward, but we were quick to realize that the challenges that lay ahead would test the very limits of the crew's skill and expertise in managing this disappearing breed of ship.

Our Captain, CDR David Portner, ensured that our training and certification were thorough. The schedule of our final upkeep was hectic - millions of dollars of specialized equipment had to be installed and tested. Additional training was also necessary to ready the crew for operation and maintenance of the new gear in a hostile and unforgiving Arctic environment. Furthermore, shipyard preparations had to be made to ensure a smooth transition for our arrival at PSNS. Moreover, Rivers Sailors were also busy at home closing the loop on last minute details in preparation for the lengthy separation from their families. Burning the candle at both ends was nothing new to the crew of the Rivers, though, and with a dedicated team effort we completed our installations and training right on schedule.

Having bid farewell to Virginia for the last time, our track took us northeast 1,500 nautical miles past the Flemish Cap before turning north for the Denmark Strait. We took advantage of our time in transit to conduct drills and training, all the way to the Marginal Ice Zone, just north of Iceland. With the last available satellite broadcast copied, we crossed under the polar ice cap.

Despite our preparations and training, isolated equipment problems on our 26-year-old boat kept us busy. The first bump in the road was the failure of our electro-magnetic (EM) log's lower pit sword, which provides speed input to the ship's navigation systems. This required us to drive the 15,000-mile journey using what is known as a "dummy log" to input ship's speed manually. Operating DMINS in the undamped mode, which was necessitated by the loss of the normal EM log input, required frequent attention from the watchstanders. Surfacing through the ice every three to five days for fixes and system resets became common.



As predicted, navigation continued to pose a challenge as we proceeded north. The ship lost all heading reference when we surfaced at the North Pole, since the Mk-19 Gyro became unstable in the high latitudes, and DMINS began to operate erratically. We tried to restart both channels of DMINS, but that quickly proved impossible. While we had fixed our position using our Global Positioning System (GPS), the ship was left surfaced at the North Pole with no compass to guide it! We had to resort to more creative methods.

The Captain calculated our heading by shooting a relative bearing to the moon and computed its Greenwich Hour Angle from the Nautical Almanac. This told us what longitude line the ship was pointing. We verified this by using a hand held GPS receiver topside, marking bow and stern waypoints and checking the bearing between them. With this information, we submerged the ship, executed a turn, recalculated our final course, and said a prayer as we headed south away from the pole to find another suitable place to surface the ship and restart our gyroscopes.

We drove 180 miles away from the pole at flank speed in deep water. We were able to approximate driving a straight line by keeping the stern marker line on the sonar display centered on own ship's sound trace in relative display mode - in other words, we "looked" backwards to make sure our wake was straight. As the Assistant Navigator, I knew that our chances for a pinpoint, hand-calculated dead-reckoning (DR) position were slim after 180 miles. When you combine unknown currents and helm error, and compound this over time, your error grows continually.

After the 180-mile sprint was complete, we found a surfaceable feature and punched through. The moment of truth had come. The GPS fix indicated that we were on the exact latitude line the quartermasters had calculated by the hand DR, but the heading error placed us 145 nautical miles due east of that position! That was tough to swallow. In hindsight, I was happy enough just being on the right chart. The Mk-19 Gyro was re-started and provided the heading reference to start DMINS.
One of the two DMINS channels came right up, but the other's inertial measurement unit (IMU) would not, and had to be replaced. Eighteen hours later, we were underway with three separate heading sources working well.

We completed our transit of the North Pole while the embarked scientific team accomplished their own goals, dropping 77 under-ice conductivity-temperature-depth probes along our track for collecting data. With the excitement of the scientific mission behind us, the only obstacle remaining was the Bering Strait passage, which would entail traveling submerged 1,000 miles inside the 100-fathom curve with ice pack overhead.

Extra watches were stationed for this slow speed transit, and a modified piloting team was manned for five days. Luckily, nothing unexpected occurred during the transit of the strait, and we chopped to our SUBPAC SUBNOTE after clearing St. Lawrence Island, setting course for our new home. We tried to make the last 1,000 miles of the voyage as uneventful as possible, even as we conducted drills and worked to qualify junior personnel for future assignments.

As we surfaced triumphantly in the Straits of Juan de Fuca and piloted into Victoria, British Columbia for a well-deserved port call, I finally had some time to reflect on the past seven weeks. PACSUBICEX 3-00 was a resounding success, and our crew was walking tall from the realization of what they had accomplished in closing a long and impressive chapter in submarine history. For more than 40 years, the U.S. Submarine Force has reigned supreme in the Arctic regions, since Skate first surfaced at the pole in 1959. And, since 1975, the L. Mendel Rivers had been there regularly to do her own part in maintaining that supremacy. With Rivers' current decommissioning, only Parche will be left to carry on the legacy of the Sturgeon-class boats. Looking back over this proud tale, I have to ask myself: Will we ever enjoy the same success we had with the Sturgeon class again, or are we retiring our one true under-ice capability for good? I hope not; because after this experience, I am convinced more than ever that we can navigate anywhere, anytime, in spite of nearly any challenge. There is a lot more to learn about the Polar Regions and I, for one, would like to go back.

Chief Beach was the Assistant Navigator of L. Mendel Rivers during PACSUBICEX 3-00 and is now the Operations Chief at Submarine Squadron Support Unit, Norfolk, Virginia.