Ships Must Practice Celestial Navigation

In February 2022, just a few miles off the coast of Oahu, Hawaii, all electronic navigation systems on the bridge of the USS Essex (LHD-2) went dark. The bridge team shifted to navigating by celestial fixes plotted on paper charts. Five days and more than 1,800 nautical miles later, the Essex arrived off the coast of San Diego, California, on time and on track.

A casualty did not cause this to happen. With the approval of the Essex’s commanding officer (CO), Captain Kelly Fletcher, her navigator (coauthor and then–Lieutenant Commander Stanton), and the lead navigation instructor from Surface Warfare Schools Command in Newport, Rhode Island (coauthor Walter O’Donnell), the Essex tested its own proof-of-concept for navigating with a total loss of integrated electronic navigation equipment. Any navigation equipment that used electricity was prohibited, including all GPS sources, the Essex’s electronic Voyage Management System (VMS), and the computer-based celestial navigation software STELLA. 

Celestial navigation competence was still necessary just a generation ago. The practice waned with the advent of more sophisticated and precise electronic navigation solutions; yet, as U.S. adversaries’ cyber and electronic warfare capabilities advanced, analog navigation techniques became relevant again. However, it is still rare for a Navy warship to intentionally operate without its electronic navigation suite. As The American Practical Navigator (aka “Bowditch”) states, “No navigator should ever become completely dependent on electronic methods. The navigator who regularly navigates by blindly pushing buttons and reading the coordinates from ‘black boxes’ will not be prepared to use basic principles to improvise solutions in an emergency.”¹

The Five-Day Exercise

The Navy conducts live-fire weapons drills, damage control drills with real smoke and fire, and exercises hunting real submarines, but it does not regularly practice for emergency, long-term, open-ocean navigation without GPS. With many vulnerabilities, GPS will likely be the first system an adversary attempts to disrupt during a war.² Captain Fletcher approved this electronics-denied voyage to assess her crew’s navigation capabilities under pressure.

Navy navigators are held to an exacting standard in shiphandling, piloting, seamanship, planning, and ocean sailing. In addition, navigators juggle many administrative tasks, such as department head and senior watch officer duties and preparations for material and administrative inspections.³ At the same time, The Surface Ship Navigation Department Organization and Regulations Manual (NavDORM) expects that “ships will be prepared to operate in a PNT [position, navigation, and timing] degraded or denied environment.”⁴ But a navigator must be always ready and able to do so.

In 2017, naval training curricula reinstated basic celestial navigation topics, ensuring junior surface warfare officers and quartermasters are oriented to fundamental concepts and vocabulary prior to entering the fleet.⁵ However, mastery of such a complex skill requires dedicated practice at sea. The Essex’s five-day celestial navigation transit should be a training template for future navigators, junior officers, and quartermasters. 

Preparation and Methodology

Prior to deployment, Lieutenant Commander Stanton conducted a celestial navigation training series for junior officers and quartermasters of the watch (QMOWs). The series moved from theory to practice, culminating in a hands-on sextant exercise from the Essex’s flying bridge. To ensure the bridge watchstanders could keep a precise and continuous paper plot, Lieutenant Commander Stanton required practice plots during both deployment transoceanic crossings (San Diego to Guam, then Japan to Oahu). The celestial plots, including a continuous plot of dead reckoning positions, were compared directly to GPS, VMS, and STELLA to hone celestial navigation skills while all sensors were still available. For maximum training effect and redundancy, two paper celestial plots were always maintained on the bridge: one by the officer of the deck and the junior officer of the deck, and another by the QMOW. 

Captain Fletcher reviewed and approved a detailed safety plan that minimized risk at all stages of the exercise. Lieutenant Commander Stanton planned the voyage on a paper gnomonic chart and in VMS, then the chart petty officer laid the track on position plotting sheets for both the junior officer plot and the QMOW plot. Lieutenant Commander Stanton reviewed available celestial bodies for the planned latitudes as well as the weather forecast for predicted sky cover percentage. During the voyage, the only operational VMS nodes (with GPS) would be in the combat information center (CIC) and the chart room. All other nodes (QMOW table, officer of the deck station, navigator’s stateroom, and VMS repeater in the CO’s cabin) were configured to keep them online for system health, but with the display unavailable to all users. The chart room node was used exclusively for the QMOW to log the ship’s position per NavDORM requirements. However, Lieutenant Commander Stanton’s guidance was to look only at the coordinates on the display and keep the view offset. CIC was to notify Lieutenant Commander Stanton if the Essex deviated more than 10 nautical miles (nm) from the planned track.

The Transit—a Firsthand Account and Impressions

During the five-day, 1,800-nm transit, the navigation team and bridge watchstanders did not use GPS, STELLA, VMS, or any GPS-derived information, including course/speed over ground. When we obtained two consecutive fixes, we calculated set and drift and course/speed made good. We used pilot charts (historical weather charts) to help predict expected leeway, set, and drift over the course of the voyage. 

We had a steep learning curve on the first day without electronics. The ship ended up 5 nm off track. In the Pacific Ocean, a 5-nm track deviation is not navigationally significant; however, it was significant to us because we expected (perhaps unrealistically) immediate precision. Fortunately, Captain Fletcher continued to trust the team. For the rest of the voyage, the ship remained within 2 nm of track, and on reaching San Diego, we were consistently plotting within 1 nm of track.

While we expected precision, we had to learn to wait longer and use fewer fixes to achieve it. We routinely navigated for 12 hours at night without a fix, when celestial navigation is all but impossible without advanced, expensive equipment (i.e., a bubble sextant). Twice during the voyage, more than 15 hours elapsed between fixes because of cloud cover. While this length of time may not surprise those who sailed prior to GPS, it is gut-wrenching in today’s Navy after years of easy access to precise, real-time data and communications. Should maintaining a celestial navigation plot become necessary in the future, bridge watch officers and all who rely on their position data will be required to do what has become unnatural at sea—wait.

Lessons

Advanced, hand-computed celestial navigation is a full-time job. It required both of us to be on (or near) the bridge for approximately 18 hours a day, especially during the morning and evening star fixes. Performing sight reduction by hand required approximately three to four hours per day. Navigators who aspire to conduct a similar voyage may use STELLA to avoid cumbersome hand computations.

The surface warfare junior officers and quartermasters loved this evolution. No longer able to stare at the VMS screen, they were liberated from the temptation to make micro course adjustments to keep the ship perfectly on the electronic track line. Not only did this save fuel, but it also gave the watch officers and quartermasters the freedom to enjoy being what they called “real sailors” as they toiled over a paper plot.

Patience and foresight are required. When a ship configured with GPS and VMS makes a course or speed change, there is immediate feedback. However, with these systems no longer in play, navigation teams must rely on past solutions to predict future success. For example, after plotting an evening star fix and obtaining the ship’s position, we calculated set and drift, noted how far left or right of track the ship was, then chose a course to correct our position in relation to track while compensating for observed set and drift. We were unable to obtain feedback on our decision until after our morning star fix—typically 12 hours later. Since the length of time between observations is so long, solutions must be minor and meticulously considered. For example, using the radian rule, steering 1 degree off base course for 12 hours at a speed of 16 knots results in nearly 3.5 nm left or right of track (565 yards per hour). 

Most navigators and senior QMs have the training to complete a similar voyage. Any Surface Navigator/Assistant Navigator Course or QM A School graduate can perform celestial navigation using only STELLA, paper charts, and plotting sheets. However, while being trained in the competencies of the craft, many navigators and quartermasters do not practice celestial navigation regularly in the fleet. Despite the fact that since 2015 the NavDORM requires that each ship conduct a celestial navigation Day’s Work in Navigation (DWIN) daily, Mr. O’Donnell has asked more than 1,000 Surface Navigator/Assistant Navigator students if they had done one and fewer than half said they had, with most admitting that celestial navigation is the first part of their jobs they sacrifice to fulfill their administrative duties. Despite the Chief of Naval Operations’ emphasis on celestial navigation, a culture of using celestial navigation daily has yet to be embraced again in the surface fleet. 

Recommendations

Whenever possible, navigators and quartermasters should take the celestial navigation skills they learned in the classroom, practice them at sea, and lead by example. Use the sextant at least once a day. Master sunlines first, then planets, stars, and finally the moon. Earn the commanding officer’s and executive officer’s trust before asking them to embark on a celestial navigation voyage. 

Start small and get creative. Unplug the Defense Advanced GPS Receiver (DAGR) on the emergency navigation laptop. Manually update the ship’s ENL position using celestial fixes for a few days, with the goal of doing it for a full voyage. Once acceptable accuracy has been achieved, go the next step and plot on charts and paper plotting sheets. Varsity-level celestial navigation is a full paper plot with sight reduction done by hand. This is the most primitive way of navigating, and mastery of it will ensure ships’ navigation teams can endure wartime conditions. 

Commanding officers must trust their navigation teams. COs will set their ship’s safety boundaries during any celestial navigation practice, and navigation teams should be free to grow as they learn within those boundaries. COs should ensure their navigation teams are completing the DWIN checklist (Appendix K in the NavDORM) every day, as the type commanders require.⁶ To hold navigation teams accountable, have the navigator submit the previous day’s DWIN checklist with 12 o’clock reports while underway. COs should take their navigators off the watchbill whenever possible so they can focus on completing and teaching celestial navigation.

Finally, ships should conduct an analog voyage on every extended transit, specifically crossing the Atlantic or Pacific Oceans. Navigators should be given autonomy and authority to tailor their methods as their teams grow more competent. 

If any ship is interested in undertaking a similar voyage, we can send them a training plan and offer distance support as they prepare. The USS Porter (DDG-78) completed a similar crossing of the Atlantic Ocean in June 2023 after her navigator and senior QM expressed interest.

In the GPS-addicted Navy, an analog voyage over long distances is a novel concept. But we did it, and other ships can, too. In wartime operations, they may have no choice.