What did you navigate?
"I was a navigator on a ballistic missile submarine during the Cold War, from 1965 to 1968. I took part in 3 deterrent patrols (with nuclear missiles for protecting the United States from the Soviet Union). At that time I was a Lt. Commander on board the USS James K. Polk (SSBN 645) as part of the blue crew. Boats had 2 crews, "Blue" crew and "Gold" crew, and we would rotate every 3 months back to home port of Submarine Base Groton, Connecticut, for training and crew turnover (roughly 1/3 of crew)."
What did you do?
"I was responsible for the accurate location of the ship at sea at all times. If, God forbid, we had to launch nuclear missiles against the Soviet Pac, the Polaris missiles had to know where they were starting from to reach targets accurately. We had to know where the ship was at all times because you never knew when you might get orders to launch.
I was the navigator. If anything went wrong, I was called. Any time we went to periscope depth, I was in the Nav Center (Navigation Center) or the Control Room monitoring navigational procedures. And then occasionally I stood watch, as the officer of the deck. In a submarine that means you run the ship."
What was the purpose of the Nav Center?
"The output of the navigation center was to provide the ship’s position and attitude (latitude, longitude, ship’s velocity, roll and pitch) to the missile control system for input into the Polaris missiles continuously. Patrols normally lasted 60 days. So the Nav Center was the heart of the ship and manned 24/7 by specially trained submarine sailors and electronics specialists."
What technologies do you use to navigate?
"We used the Transit satellites, Loran C, bottom-contour navigation and celestial navigation fixes to update the Ship's Inertial Navigation Systems (the SINS)."
What was the SINS?
The SINS (Ship's Inertial Navigation System) was in the Navigation Center of the ship, as was all the navigation equipment. The SINS maintained the ship’s position at all times through a system of gyroscopes, accelerometers, and velocity meters. All this equipment was controlled through the Navigation Data Computer, a big computer in the Nav Center. This was one of the first large-scale computer systems in the Navy. When these ships went to sea in the ’60s, it was the first time digital equipment was used in a weapons systems. It was a breakthrough, like the MARDAN and the Navigation Data Computer. We had six or seven computers—the MARDAN that ran the SINS, a computer that ran the Transit system, and a computer that ran the LORAN system, and over the top of all of these, we had the NAVDAC (Navigation Data Computer). SINS position was plotted every half hour on graph paper. These positions were compared to fixes taken by LORAN C, Transit, bottom-contour or celestial navigation fixes. If the SINS position exceeded the required accuracy based on external fixes, the SINS position was corrected through the computer system.
What is Bottom-Contour Navigation?
"Bottom-Contour Navigation used specific bottom-contour charts and sonar to fix a ship’s position. These were very highly measured areas, and we’d run across them several times and fix position with soundings . For the soundings, we could vary the power of the sonar—we were putting sound in the water--to avoid detection."
Why did you use LORAN-C?
"The mission of the ship was to remain undetected, so that no one knew where the boat was. Any activity at periscope depth with mast exposed could result in detection, either by friendly or unfriendly forces. So the captain wouldn’t let me go up as often as I wanted and made me rely on LORAN C. LORAN C was continuously copied on a floating wire antenna while remaining deep, because of its frequency. The antenna floated just below the surface, trailed behind the ship out to, I think it was 1500 feet. LORAN C was less accurate than Transit.
How did you use a satellite system, like Transit, if you were underwater?
"For Transit fixes, we had to go to periscope depth and raise a special antenna. In those days we didn’t get a Transit fix very often, maybe once every 3 days, because we had continuous LORAN coverage. We were at periscope depth for about 15 minutes, and we’d track the satellite from time of rise to the time it set."
Why did it take so long compared to GPS?
"It was the Doppler system with 2 frequencies and we had to listen for a period of time to both frequencies."
How did you use celestial navigation?
"We used a specialized periscope with a very accurate built-in sextant to compute the ship’s position and heading, using normal celestial sighting procedures. The periscope system had its own computer, it had all the stars in the computer, and the timing was in the computer. And it did all the calculations to compute the fix. You prepared for it by coming up, and asking the computer—based on current position—what stars were available, and then all the stars were loaded. You got the results in half a minute, a beautiful piece of work. The periscope was computer –controlled, and the computer contained all the celestial information needed to detect, measure the position of stars, and compute the fix. The drawback was when using the celestial periscope; you had to be at periscope in clear weather, which increased detectability of the ship. We did this maybe once a week. This periscope was removed from use when the Poseidon missile replaced the Polaris missile in the early ‘70s, because of improvements in the SINS. The SSBNs didn’t need celestial navigation any more, but it was still used by the attack boats."
What were some challenges you faced while being a submarine navigator?
"We had to maintain specific accuracy requirements for speed and position. The requirements were for missile accuracy if we had to launch. Performance was monitored after the patrol by Johns Hopkins Applied Physics Laboratory (APL) under government contract. Every piece of data, navigations and weapons data, were part of the package provided by the ship to APL. The IBM typewriter printed out everything the SINS was doing, and that was part of the patrol report. During the patrols the crews were tested on their ability to launch by random exercises to conduct simulated launches on a no-notice basis. We had pop quizzes. These tests were evaluated by Johns Hopkins APL after every patrol. These tests evaluated the ship’s performance in navigation, missile accuracy, missile readiness and ship’s communications. Every six months, a report evaluating the performance of the fleet ballistic missile submarine force went to the Joint Chiefs of Staff. They cared very deeply about that performance, because they wanted to see how effective the nation’s nuclear deterrent was against the Soviet Union."
