By Michael Carr – They were lost. Lost in the open ocean off Antarctica. Two miles to their starboard should be the Ross Ice Shelf, a 200 ft. high vertical wall of ice running for hundreds of miles along Antarctica. Instead there was just Open Ocean. This situation was definitely not part of their DeepFreeze79 operation.
Ensign Bill Davis, the USCGC Glacier’s (WAGB-4) Navigation Officer had just come to the bridge to relieve the mid-watch and assume OOD for the 4-8 watch. Bill was looking forward to an easy and uneventful watch, as they steamed east along the edge of Ross Ice Shelf, having departed McMurdo Station a few days earlier.
Night Orders, signed by the USCGC Glacier’s Commanding Officer the previous evening, clearly stated to steam east at 12 knots, maintaining a distance of 2.0 miles off the Ross Ice Shelf. As Bill climbed the ladder to the Glacier’s bridge there was no need for his eye’s to adjust to a dark bridge, is was summer in the Antarctic, with the sun shinning all day. But as he entered the bridge, he was immediately concerned. He peered at both the radar and sea horizon; there was no Ross Ice Shelf.
He increased the radar’s range, from 6 miles, out to 12, 24, 48, 96 miles, but there was nothing, just a black screen with the radars sweeping cursor.
He looked at the gyro repeater, they appeared to be heading east, if the gyro compass card could be believed, but something was not right.
“Where is the Ross Ice Shelf” he asked the off going OOD, “I can’t relieve you, or the watch, until we establish a fix, and I can’t determine where we are.”
A distraught look creped over the off going OOD’s face. He looked out the starboard bridge windows, then at the radar, then at the gyrocompass. Bill could tell there was a real problem; the present watch did not know they were lost.
“Captain, this is Ensign Davis on the bridge. We are lost.” Bill made this call to the ship’s skipper without hesitating. Every Coast Guard deck watch officer is taught to immediately call the Skipper when anything on the ship is not right. And the Night Orders specifically stated, “Maintain a distance of 2.0 miles off the Ross Ice Shelf”, and now there was just open ocean. One possibility was Antarctica had sunk or melted in the past few days or hours, but another more likely possibility was something amiss in the ship’s navigation.
Bill methodically began checking the gyro and radar again. He looked at the Sun, which was always above the horizon this time of year. Near the South, and North, Poles magnetic forces are nearly vertical to the earth’s surface, causing a magnetic compass to be unable to orient itself. Magnetic compass cards just wander. Ocean depths are too deep for soundings. NAVSAT fixes only come every few hours, and are often not easy to capture. (Note: GPS has not yet been invented).
Bill soon realized the sun’s azimuth for this time of day was wrong. And then, as he checked the gyro repeaters, and checked the master gyro, they were all showing different headings.
Glacier had suffered a gyro failure. There had been no alarm, or indication as to when the gyro failed, but it had been sufficiently long for the Ross Ice Shelf to disappear as the USCGC Glacier apparently sailed out to sea, following wandering and erratic gyro headings.
Bill now had to find a method for establishing his ship’s position and steer a course.
“Everyone listen up” he announced to the oncoming bridge watch, “We have suffered a gyro casualty, and have been sailing random courses for an indeterminate time. We need to establish our position and a method to steer a course.”
Bill already knew what he would do.
“Go wake up the helicopter pilots,” he instructed the Bos’nmate of the watch. “Tell them we need their helicopter’s gyro powered up.” Every Coast Guard Icebreaker carries a helicopter onboard, and every helicopter has a gyrocompass. Fire up the gyro, place a crewman in the helicopter wearing sound powered phones, and they can communicate true courses to the bridge.
Bill smiled to himself as he sent the bos’n down to wake up the helicopter pilots. When the helo was not flying the pilots often had a carefree life onboard; watch movies and eat popcorn in the wardroom, and sleep through the night, while the ship’s crew were standing “four on eight off” watches. “Sorry to interrupt your movie time, but we need your helo’s gyro…”
Bill focused on capturing the next SATNAV pass, computed azimuths to the Sun and soon had the bridge helmsman steering a true course relayed from the helicopter. As the crewman in the helo informed the bridge crew of the ships heading the helmsman would use the magnetic course as a reference. It did not matter what heading was being shown on the magnetic compass, it was now just a “number” which gave them a momentary correct heading. Bill had the helicopter crewman update the bridge helmsman every 15 minutes.
Soon Bill had the ship heading back towards the Ross Ice Shelf, and within a day the prominent ice wall again appeared on radar. They would return to McMurdo station for repairs, this time keeping the Ross Ice Shelf to port!
As Bill drafted new Night Orders he wrote, “Use all available means of navigation to establish your hourly fixes. Consider true and relative wind, swells, seas, radar bearings and ranges, compare magnetic and gyro readings, and compare with your DR.” Then he added, “Wake me and the Captain if there are issues with establishing hourly fixes”.
As Bill walked the bridge on the Glacier’s return to McMurdo, he kept glancing over to port, ensuring the Ross Ice Shelf did not again disappear.