The Shipwreck Hunter

by David L. Mearns

  The length of the search box was born out of the uncertainty about whether Derniers’ 26° 34’ south, 111° east position was the noon position or the battle position. Although my box would cover both scenarios, I had one final clue to help me determine the more likely of the two. One of Kormoran’s life rafts, heavily loaded with twenty-five young Germans, was the earliest to be picked up at sea by a passing troop transport, the converted Cunard liner Aquitania. As the time the raft left Kormoran and the time and position it was recovered eighty-two hours later were all known, I’d be able to calculate where it started if I could just determine the speed and direction it had drifted over that period. Since the sinking position of Kormoran and the starting point of the raft were essentially one and the same, I saw this reverse-drift analysis as a way to corroborate the German positions using independent information, and to help me resolve the uncertainty about Derniers’ 26° 34’ south, 111° east position.

  An object floating on the ocean drifts at a speed equal to the sum of the velocity of water (the current) and the velocity of the object, with respect to the water, as a function of the wind speed (leeway). Every object reacts differently to the force of the wind, depending on how much of its surface area is exposed. For example, objects floating high with a lot of area above the sea surface will drift quickly, whereas objects that lie low in the water will drift more slowly. An empirically derived number called leeway factor can be used to calculate leeway speed as a percentage of wind speed. Fortunately, leeway factors for different types of life rafts, including World War II vintage rubber rafts, are known from field studies conducted by the search and recovery (SAR) community. In the case of Kormoran’s raft, I’d be able to get a reasonable estimate of its total drift as long as I could somehow determine what the current and wind speeds and directions would have been in late November 1941.

  To get the most scientifically robust data, I decided to commission two brand-new studies, one on historical wind conditions by Len van Burgel, a professional meteorologist, and the other on currents by Dr David Griffin, a physical oceanographer from the CSIRO Marine and Atmospheric Research Division based in Hobart. Other researchers had tried this for the 1991 symposium, but in early 2008 we had the advantage of computerized databases that gave us access to much more precise data over long periods, 1968–2007 for winds and 1992–2006 for currents, to pick out dates that most closely matched the conditions in late November 1941.

  Dr Griffin, who ran BLUElink, an ocean-forecasting system based on satellite-derived data and advanced supercomputer processing, produced the final chart of trajectories that showed possible locations where the raffs could have been launched. In addition to the raft picked up by Aquitania, I also had analysis run for a second raff picked up 115 hours later by the SS Trocas. The picture was complicated by the fact that the dominant current in this part of the world, the Leeuwin current, is highly variable because of random instabilities leading to the formation of transient eddy currents. Before the BLUElink project was initiated in 2003, physical oceanographers were more or less unaware that these large, swirling and unpredictable currents even existed. For this reason any previous attempt to pinpoint the sinking position of Kormoran based upon drift analysis was pretty much an exercise in futility. There was simply no way of knowing what the current field looked like in late November 1941 or how eddy currents might have affected the rafts’ drift.

  Instead of a single trajectory based on the average current conditions, which would have been entirely misleading, I explained to Griffin that what I wanted to see was the full range of trajectories from as many representative scenarios as he could extract from the BLUElink dataset. He produced a total of 300 for each raft, each representing daily surface currents from the latter half of November for a consecutive fifteen-year period up to 2006 and for years when the southward-flowing Leeuwin current was weaker than normal. The final results reached me the day before our survey vessel Geosounder was scheduled to leave Geraldton for the long voyage north to the search area, and they had an immediate impact on my search plans.

  Griffin’s chart of back-calculated launch points didn’t tell me where Kormoran had sunk. It wasn’t intended to. What it did do was show me all the possible positions where the two rafts could have departed from the ship. Because some of the launch points did start at or around Derniers’ 26° 34’ south, 111° east position, it meant I couldn’t automatically rule this out as the battle position and still needed the search box to be large enough to cover this area. However, as most of the launch points were all well north of Derniers’ position, the clear indication was that 26° 34’ south, 111° east was more likely to be the noon position of Kormoran on the day of the battle as Wes Olson first postulated and I had been trying to prove ever since.

  At a press conference in Geraldton’s town hall the next morning, I gave the media and the public a short presentation about my research and search plans. I explained the science behind the reverse-drift analysis and the confidence it gave me in the belief that Kormoran’s wreck was most probably located in the north-eastern quadrant of my overall search box. This was the new high-probability area and I would arrange the sequence of track-lines to ensure it was searched first. Although I still expected to find Kormoran before Sydney, I prepared everyone for the possibility that the sequence of discovery could actually be reversed. This was one benefit of maintaining the extended length of the search box: that it also covered areas to the south where there was a good chance Sydney’s wreck was located. The long period of research had come to an end. It was finally time to see whether the Germans had actually been telling the truth about where they fought the Sydney.

  Searching the deep ocean for wrecks is a complex and risky operation that rarely goes perfectly to plan. All sorts of problems crop up that in extreme cases can mean the difference between success and failure. The main culprits are rough weather and equipment failure. But over the course of my career I’ve had projects stopped dead in their tracks for a host of other unexpected reasons, including ships breaking down or catching fire, injuries to personnel requiring helicopter medevac, loss of sonar towfishes and ROVs, and in one instance literally running out of food, prompting an urgent return to port. This is why we always have contingencies in the form of extra days built into our schedule. The other form of protection is to carry plenty of spare parts, especially for mission-critical pieces of equipment. So for a lengthy search like the one we were about to start, I had to expect some problems and losses of time. What I didn’t expect was that the problems would start before we even left Geraldton harbour.

  The company that HMA3S had hired to conduct the search operations was the Seattle-based geophysical survey contractor Williamson & Associates. Despite their small size – maybe twenty or thirty full-time employees and offshore contractors – they were one of the world leaders in the field of deep-water searching and had the type of wide-swath side-scan sonar systems I felt were best suited to this particular search. I knew the company very well, having worked with them in the past, and was happy to be going to sea with such an experienced team. I also knew, however, that because the pool of deep-water search contractors to choose from was so small, HMA3S had had little choice beyond Williamson. In fact they were virtually handed the job when the only other company in the running had to withdraw from the selection process because of a scheduling conflict.

  Having worked all around the world, Art Wright, Williamson’s party chief, understood the challenge of running such a high-profile job in a remote part of the world far from their Seattle base. For that reason he made sure he brought lots of spare equipment; most importantly, a back-up deep-tow winch fitted with 10,000 metres of cable and a second side-scan sonar system. These were essential pieces of equipment, because while without a sonar you obviously can’t conduct a search, equally, without a winch or cable you can’t operate a sonar. The comfort I felt from seeing the two large, heavy winches welded to the deck of the Geosounder turned to dread the morning
we were scheduled to get under way when Art broke the bad news that the high-voltage electrical core of their primary tow cable had shorted, rendering this winch-and-cable combo unusable. That meant that the spare winch was now the primary, and the broken primary served no further purpose for the entire duration of the search other than being twenty-two tons of dead weight whose position on deck left the ship with a nauseating tendency to roll in moderate seas.

  I was still bemoaning the loss of the winch and cable a few hours later as the Geosounder pulled away from the quayside and began to make her way towards the protective breakwaters at the entrance of Geraldton harbour. It was a big moment for the town, and for Western Australia. People gathered to wave us off while television news crews filmed us from land and a helicopter circled overhead. There was a palpable sense of excitement and anticipation for what was to come over the next several weeks, and the cloud of anxiety that had hung over the ship throughout the day had lifted in the fresh southerly breeze. I had come up to the boat deck to take in the scene and was joined by Glenys and Carter Huynh Le, Williamson’s electrical engineer. We watched as the pilot boat came alongside to retrieve the local port pilot, signalling that command had been handed back to Geosounders captain, Blair Cliffe. Not a minute later, the ship’s loudspeaker shattered the mood by requesting my urgent presence on the bridge. The last thing a captain wants when entering or leaving port is extra bodies on the bridge, so I knew something was drastically wrong.

  When I got to the bridge, the concern etched on Blair’s face confirmed my worst fears. A fuel leak in the engine room had caused it to fill with great clouds of smoke. No fire was reported, but the risk of one breaking out meant we needed to urgently find a safe anchorage to stop the ship and assess the severity of the situation. There were some very tense moments on the bridge trying to get Geosounder over to the anchorage just north of the harbour without running aground on an area of shoals and without getting the props fouled on the floats and lines of crayfish pots. While John Perryman acted as an additional lookout, I was steadily calling the depth under the keel from the echosounder to help Blair and his second mate get the ship anchored without further incident.

  The leak wasn’t big, but it was in the worst possible place, with the fuel streaming down from a hairline crack in an overhead tank on to a red-hot engine exhaust covered with lagging that started to smoulder and create smoke. Fortunately the engines hadn’t been running long and the leak was caught early. Had we been at sea for longer, the combination of fuel oil and heat could easily have ignited a real fire. The ship’s engineers worked feverishly to patch the crack, but nothing they tried could stem the persistent stream of diesel pissing down on them. As much as I hated the idea, and the embarrassment, of limping back into port with our tail between our legs, we had to get the tank bottom properly repaired by welders, which also meant pumping out the forty tons of diesel fuel it contained. To make matters worse, it was a holiday weekend, so I could see us losing two to three days, or worse, to make the repairs.

  At times like these you rely on your teammates, and I had one of the best in Patrick Flynn, the project manager HMA3S had hired to handle all the shore-side logistics and media enquiries. As soon as I called Patrick from the ship, he was immediately on the case. The next morning when we returned to port he had two road tankers waiting for us to remove all the fuel and vent the tank of dangerous gases so the welders could get to work. With the ship patched up and refuelled, we were ready first thing Monday morning for the pilot to guide Geosounder back out through the harbour entrance, this time without a repeat of the dramas of Friday afternoon. The leak did cost two and a half days of my schedule, but without Patrick driving the repair, it could have been twice as bad.

  My original plan to cover the 1,768 square nautical mile search box was based on searching a grid of twelve north-to-south track-lines using Williamson’s wide-swath SM-30 sonar. This low-frequency sonar (30 kHz) had enormous capability for covering a swath of up to six kilometres while still being able to detect wrecks the size of Kormoran and Sydney. If any wreck-like targets were detected, we’d then switch to the high-frequency AMS-60 sonar (60 kHz) to collect better-quality images that would allow us to identify the wrecks. As my entire search plan relied on being able to cover the seabed at a high rate with the SM-30, I was pinning all my hopes on how it would actually perform. Sonar performance was so important that before steaming up to the search area, we conducted a series of commissioning tests west of the Abrolhos Islands using both sonars just to make sure they were producing the quality of images I expected.

  I chose a central track-line (number 7) just east of the 111° longitude to get an indication of what the seabed through the heart of my search box looked like. We purposely began outside the box to give the Williamson technicians plenty of time to tune in the SM-30 and for the ship’s drivers to find the best heading and speed to run the track-line. With 7,000 metres of tow cable deployed and Geosounder crawling along at 2.8 knots, the sonar towfish was more than three nautical miles behind the ship at all times. I considered this to be a practice/reconnaissance line that, if need be, could be rerun if the sonar imagery wasn’t up to scratch or we weren’t getting 100 per cent coverage of the seabed. At one ping per four seconds it takes a fair amount of time before a coherent image of the seabed can be generated.

  An hour later the verdict was in and it wasn’t good. Despite performing well during the commissioning test, a technical fault with the SM-30 cropped up that left it producing poor-quality images. So poor, in fact, that I asked Art Wright to recover the towfish after it reached the end of the track-line to fix whatever problem had developed. The imagery was also being blighted by acoustic noise at the sea surface. One quirk of side-scan sonars is that they can ‘see’ above as well as below, and in situations where the range to the surface is less than the operating range of the sonar they will pick up acoustic noise from surface waves. As we were towing the SM-30 at a depth of 2,200 metres, but searching at a range of 3,000 metres (half the six-kilometre swath), the sea surface returns were effectively masking the outer 800 metres of seabed imagery on both the port and starboard channels. The net result was that we were only searching 70 per cent of the seabed I planned for each track-line to cover.

  I drew a diagram to show John Perryman how the geometry of the situation was working against us, and explained that it would be better if we were searching in deeper water. He was surprised by this, but understood the dilemma I faced. I could no longer cover the search box with twelve track-lines, because of the reduced range, and had to increase the number to seventeen, costing us an additional four days. Together with the fuel leak and an extra day needed during the mobilization, the total hit from these losses to my planning was seven and a half days. Suddenly the original healthy budget of thirty at-sea days was beginning to look a little anaemic, and the safe margin of extra time I thought we would have was evaporating. We were off to a bad start that put everyone under pressure, and that pressure was about to mount in the coming days.

  The man in the hot seat to fix the ailing SM-30 sonar was Carter Le, a hard-working engineer who had emigrated from Vietnam to study electrical engineering at the University of Washington. At first the problem appeared to be minor. A damaged cable was found and replaced, eliminating the electrical ground fault. However, further tests revealed more serious faults of the core electronics within the towfish. For the next forty hours, Carter slaved over the twin five-foot-long racks full of electronic circuit boards and power supplies to fix what seemed to be an endless array of broken components. It was tedious, complicated work made incredibly difficult by lack of sleep, pressure from the search being stopped, and the pitching and rolling of the Geosounder. The small white patch behind Carter’s ear marked him as someone who suffered from seasickness, and I was concerned how he was holding up in the less than ideal conditions.

  The culprit behind the rough weather was a tropical cyclone that had been harmlessly spinning her way into
the Indian Ocean well north of our position before gradually veering south towards us. Ophelia was a Category 2 cyclone with maximum sustained winds of 100 kilometres per hour that changed course and headed menacingly our way as soon as we arrived on site to begin the search. I was receiving updates from Australia’s Bureau of Meteorology (BOM) every twelve hours, and each one showed Ophelia getting closer. Only the gods knew how hard we were going to be hit, but our current misfortune was certainly about to be compounded by a spell of weather downtime. If there was a silver lining to the forecast it was that Ophelia was bound to weaken as she reached the colder southern waters where we were searching.

  The SM-30 towfish was in the water for yet another test when the latest BOM forecast showed that Ophelia had changed course again and was now heading directly towards our position. I was getting seriously hacked off by this storm, which possessed an unerring ability to home in on us like a guided missile. The wind was blowing 27 knots and the weather conditions were already marginal for attempting a towfish recovery, but with expected 45–50-knot winds on their way, we had to make a decision. Art Wright wanted to leave the towfish in the water and hunker down till it passed, but I thought that was tempting fate with such an unpredictable storm. We’d have more options with the towfish out of the water and safely secured, so I overruled Art and had his team prepare for a night-time recovery. Once the SM-30 was on deck, I asked Blair to begin steaming to the north-east, which would keep us ahead of Ophelia and give us the most comfortable ride into the three-and-a-half-metre swells.