Marine forensics: deep revelations

Ships have been sinking for as long as men have ventured onto the oceans. In many instances, the reasons for these casualties were buried in the seabed, their root causes and possible lessons out of reach.

Jason Jr., a camera-equipped robot submersible, peers into a first-class cabin of Titanic.

Now this age-old resignation is giving way to understanding. Behind the change are impressive advances in the field of marine forensics, which uses science and technology to peel away the mystery of undersea wrecks, past and present. Slowly – perhaps too slowly, some experts say – marine forensics is leading to a new generation of safer vessels.

The advent of modern marine forensics was born of tragedy. Workmen at the Portsmouth Naval Shipyard in Kittery, Maine, had just completed an overhaul of the nuclear submarine Thresher before it left for a test dive in the Atlantic Ocean on April 10, 1963. The world’s most advanced submarine, Thresher never resurfaced. Her last message received by a nearby Navy ship was “Attempting to blow.”

The Thresher disaster left 129 crewmembers and observers dead on the bottom. It also left the need to find out what had happened. At the time, the best submersible available to reach the disintegrated sub was the bathyscaph Trieste, a two-person craft built in 1958 for deep-ocean research. Trieste’s crew could take photos from inside the vessel. For the Thresher mission, Trieste was modified to carry sonar and cameras to locate the wreckage.

However, Trieste was essentially an elevator that could submerge at 2 knots and had a visual search area of only 100 feet. It took weeks before Trieste located the remains of Thresher in 8,400 feet of water.

Special manipulator arms, operated from inside the bathyscaph, retrieved a piece of metal 56 inches long. From this and other information, investigators theorized that a leak developed at a silver-brazed joint in an engine room seawater system. Water from that leak may have short-circuited electrical equipment and triggered cascading problems that doomed the sub.

The loss of Thresher prompted the Navy to encourage the development of equipment that could recover objects from the deep oceans. A new generation of underwater vehicle technology was put to work in 1985, when Robert Ballard of the Woods Hole Oceanographic Institution joined with a French team to search for the wreck of RMS Titanic. They found it in 12,400 feet of water.

A year later, Ballard returned to the wreck site to explore and photograph both the exterior and some of the insides of Titanic. He was aided by Jason Jr., a prototype remotely operated vehicle (ROV). Jason Jr. was tethered to Alvin, Woods Hole’s three-person, deep-diving submersible.

Giant tears of rust known as rusticles stream from the bow. The elongated formations reflect the way rust forms in deep areas of the ocean. The technology used to find and explore Titanic made possible the development of marine forensics.

The 1985 and 1986 explorations of Titanic were milestones in the quest to learn more about the cause of the 1912 sinking of one of the world’s greatest passenger ships. They also ushered in the modern era of researching maritime casualties.

“Marine forensics as we know it really began around that time,” William Garzke Jr. said.

Garzke is the chairman of the Society of Naval Architects and Marine Engineers Marine Forensics Panel. This group of experts includes metallurgists, microbiologists, geologists, archeologists, historians, naval architects, marine engineers and operators of remote-sensing equipment.

Other wrecks under study by the panel include RMS Lusitania, the British battle cruiser HMS Hood, the German battleship Bismarck, and the hospital ship HMHS Britannic, sister ship of Titanic.

“We have been learning some things about ship design from the losses of the Titanic, Britannic and Lusitania that should be put into practice of modern-day passenger ships,” Garzke said.

The panel’s 1996 and 1998 investigations of Titanic used the scientific study of metals to analyze the steel plates and rivets from the hull, as well as instruments that transmit and receive low-frequency sound waves to study damage to the bow from the collision with the iceberg.

Among the key findings: Titanic’s hull steel wasn’t brittle, as first theorized in 1993. The flooding resulted from a series of six thin slits – not a 300-foot-long gash – that opened the ship’s side. The flooding was caused by failure of rivets in the area of the ship-iceberg collision.




An A-frame on research vessel Atlantis lifts Alvin from the ocean. Alvin, a three-person, deep-diving submersible was used to reach the wreck of Titanic 12,400 feet below the surface.

The landmark paper, “The Sinking of the Titanic, Investigated by Modern Techniques,” published by John Bedford and Christopher Hackett in the United Kingdom, showed that the initial flooding area was only 12 square feet. Modern computer analysis has now shown that the rivet-joint efficiency of double-riveted, lapped longitudinal seams was only 27 percent, compared with a 100 percent joint efficiency for present-day welded structures.

Efficiency is a measure of the strength of the joint relative to the strength of the steel plates being joined. 100 percent efficiency means that the riveted seam is equal in strength to the steel plates being joined. A rating of 50 percent means that the riveted joint would be half as strong as the steel around it.

The rivets have also been metallurgically tested. Nineteen of 48 wrought-iron rivets retrieved from the wreck have shown an elevated slag content, much higher than the 2 to 3 percent that is normal.

The shipbuilder complied with the rules of the time, Garzke said. But steel shipbuilding was an emerging technology during the construction of the Olympic Class passenger ships.

Finite element analysis has been used since the 1960s to predict stresses in ships. However, advances in computer technology in the last 40 years have dramatically improved this technique. Those techniques were applied to Titanic. Its structure was graphically modeled using plate elements. The mass distribution for non-structural and unmodeled structural weights was determined from an estimated distribution of weights and loads at the moment of hull failure.

The stress analysis, combined with a metallurgical analysis of the hull steel recovered in August 1998, determined that the ship’s hull broke apart before the vessel sank. An estimated 35,000 tons of seawater flooded the forward 300-foot portion of the ship, Garzke said. The bending forces were so massive that the best of modern steels would have been powerless to resist them. “The ship wasn’t designed to be a semi-submersible,” Garzke said.

These studies provide more than historic interest, according to William Cleary Jr., a former chief naval architect in the Coast Guard’s Technical Division of the Office of Merchant Marine Safety and a member of the Marine Forensics Panel. By helping explain maritime disasters of the past, the information could help today’s designers and captains avoid similar errors in the future.

A new generation of unmanned submersibles – autonomous underwater vehicles (AUVs) – will open a new window for marine forensics. Programmed to explore wrecks and the ocean floor, they can send back data for weeks at a time. No longer will sea conditions and weather be a problem for exploration. Their development marks a sharp contrast to the state of affairs just a generation ago.

“There’s been a lot of frustration,” Clearly said, “that once a ship went under the waves, all you could do is say a few words of prayer and forget about it.”

The question now, Cleary said, is to what degree the industry will embrace the new tools and the lessons being learned. Despite improvements and changes in procedures in response to modern casualties, Cleary said, political and financial inertia is holding back progress. “I’m impatient that we’re not moving faster,” he said.

Forensic science has become familiar to the public through the use of DNA analysis to solve crimes. Marine forensics uses science and technology to learn the cause of maritime disasters. Garzke said he likes to think of the new field as “reverse engineering,” because researchers know how the ship was constructed and then have to find out how things unraveled during the sinking process.

Much of the recent discussion about Titanic has focused on the integrity of the hull during a flooding event and to what degree modern passenger ships are better designed. But there is also an important human lesson from the Titanic disaster, Garzke said, involving the need for crews trained in damage control.

Because Titanic sank from openings that amounted to only 12 square feet, it’s possible that a well-trained damage control team with the proper tools and materials could have plugged the holes and slowed the flooding. That might have bought precious time for rescue ships to arrive and save more of the passengers and crew. The lack of trained, equipped damage-control teams on passenger ships remains a concern in the maritime industry.

“A small cadre of the crew should be trained for damage control procedures,” Garzke said.

The technology used to uncover Titanic in 1985 was deployed in 1997 to study the wreck of M/V Derbyshire, the largest British merchant ship ever lost at sea. The 964-foot bulk carrier went down with 44 people in Typhoon Orchid off Okinawa, Japan, in September 1980.



The stern of Derbyshire lies on the bottom of the Pacific off the coast of Okinawa, Japan. The 964-foot bulk carrier sank in 1980 with the loss of 44 lives. An initial inquiry blamed the sinking on a powerful storm. A later analysis employing deep-diving technology and marine forensic analysis showed that the failure of the hatch covers was the cause.That revelation demonstrated the power of marine forensics for understanding shipwrecks.

An initial inquiry attributed the sinking to 80- to 100-foot waves and the strength of the storm. But after a sister ship, Kowloon Bridge, went aground and broke up off the Irish coast in 1989, a new probe was ordered by the British government.

In 1995, the wreck of Derbyshire was found in 10,000 feet of water. A team from Woods Hole used the Argo II, a towed imaging system, a sidescan sonar system and the Medea/Jason ROV to explore the wreck and its debris field, photograph it and examine pieces of wreckage. Digital cameras and fiber-optic cables helped bring back high-resolution images to analyze data aboard the ship.

A European Commission member on the discovery trip and also a member of the Marine Forensics Panel, Robin Williams, said at the time: “It clearly demonstrates that it is now possible to find and examine any sunken vessel to seek to establish the cause of loss. No longer need ships vanish without trace or explanation.”

Studies since the 1997 exploration of the wreck site have determined that flooding of the forward spaces increased the probability of deck wetness, which led to the failure of No. 1 hatch covers.

“The ship was like a beach with waves over 80 feet high breaking on the deck structure and hatches,” Garzke said.

This observation was also supported by a major series of model tests carried out at MARIN Model Basin in the Netherlands, and a new approach to the statistical analysis of unusual events. These model tests were carried out in order to generate the basis of new rules on freeboard and hatch-cover strength to be put forward to the International Maritime Organization and the International Association of Classification Societies for bulk carriers.

The growth of marine forensics suggests the time is coming when shipping accidents will routinely be treated like plane crashes. Aviation forensics, then, becomes a relevant model. But Cleary said there are limitations.

In the United States, the U.S. Coast Guard and the Federal Aviation Administration have similar authority, Cleary said. But there’s no equivalent flight data recorder on a ship. And it’s rare that authorities order pieces of a sunken vessel to be pulled from the depths of the ocean and reassembled to learn the root cause.

“The thinking,” Cleary said, “has been that it’s the captain’s fault if something happens. There’s a reluctance to use the tools and technology that’s available.”

Politics led to one notable exception in Russia. President Vladimir Putin vowed to determine the cause of the loss of the nuclear submarine Kursk and to recover the 118 bodies aboard the vessel that sank in 2000 following an explosion in the Barents Sea.

It took the Dutch salvage company Mammoet 15 hours and a force of 9,000 tons to lift the wreck. The salvage operation was completed in October 2001. Investigators are now searching for clues to what caused the explosion.

Despite the growth of marine forensics, politics, financial considerations and human error continue to trigger accidents on the high seas.

In December 2000, the Maltese-registered oil tanker Erika broke apart in a storm off France’s Brittany coast. The sinking didn’t make big headlines in the United States, but the 10,000 tons of heavy oil that fouled the French coast caused massive pollution. “It really became the Exxon Valdez of Europe,” Cleary said.

Forensic techniques and underwater photographs of the wreck led to the conclusion that a crack in the hull below the waterline was misjudged and mishandled in the 25-year-old vessel, according to RINA, the Italian classification society. The crack may have resulted from a defect or brittle fracture, investigators said, which led to a progressive structural failure and sinking within 18 hours.

In the wake of Erika’s sinking, the European Union is working to tighten tanker safety rules.

“That’s where forensics is really opening the door for us,” Cleary said.

By Professional Mariner Staff