Navigation errors placed the Argo Merchant about twenty-five miles off its intended course, causing the ship to run aground near the Massachusetts coast and break up. Fortunately, steady winds from the west pushed the oil out to sea, and the oil did not contaminate the seafloor.

By modern standards, the Argo Merchant was not a big tanker. The ship measured slightly more than six hundred feet in length, eighty-four feet in breadth, and its draft, or depth below the water, was nearly thirty-five feet. Howaldtswerke A. G. of Hamburg, Germany, built the ship in 1953, and its first owner christened it Arcturus, for one of the stars used in navigation. It subsequently had several owners and several names. In 1976, it was owned by a Liberian company with a Greek name, Thebes Shipping, Inc. By that time, it had suffered many breakdowns and had been towed into port at least twice. Oil spills
Disasters;oil spills
Ecological disasters
Papadopoulos, George
Dukakis, Michael
Hein, Lynn

In early December, 1976, the Argo Merchant sailed from Puerto La Cruz, Venezuela, with a cargo of 28,000 tons of heavy fuel oil to be delivered at Salem, Massachusetts. It made a normal trip across the Caribbean Sea and headed up the East Coast of the United States. On December 12, the Argo Merchant passed Diamond Shoal light off Cape Hatteras, North Carolina. From there, the ship aimed for Nantucket lightship just off the island of Nantucket. The voyage was about three days.

Nantucket lightship marks the southeastern end of shallow water extending out from Nantucket Island. Ships traveling up the East Coast normally take pains to pass the lightship so that it is on their port, or left, side. This assures that they remain in deep water.

Because the Argo Merchant passed within sight of land off Cape Hatteras, its position was accurately determined through the taking of compass bearings to landmarks shown on the nautical chart. During the run from Diamond Shoal to Nantucket, more complicated navigational methods were needed, as land was not in sight. Ships use two types of compasses to determine their direction of travel. The simpler of these is a magnetic compass. A ship’s magnetic compass is a larger and more accurate version of the pocket compasses that hikers sometimes use. A ship also uses a gyrocompass, a complex electromechanical device based on a gyroscope. The gyrocompass points to the true North Pole, and a ship normally sets its course by this instrument. Both kinds of compasses mark north as 000 degrees, east as 090 degrees, south as 180 degrees, and west as 270 degrees.

The Argo Merchant spills its oil into rough seas, about twenty-five miles southeast of Nantucket Island, Massachusetts, in 1976.

(National Oceanic and Atmospheric Administration)

Magnetic compasses point to the magnetic pole rather than to the true North Pole, so the direction indicated by a magnetic compass is not the true direction. “Variation” is the term used to describe this discrepancy. Off Cape Hatteras, the variation caused the Argo Merchant’s course to read about 8 degrees greater on the magnetic compass than on the gyrocompass. The ship was steering 040 degrees by the gyrocompass, equivalent to 048 degrees by the magnetic compass. Variation increases as a ship travels up the East Coast, so the magnetic compass gives an increasing reading if the ship’s true course remains the same.

A strong wind was blowing from the west as the Argo Merchant headed away from Cape Hatteras. Because the captain knew that the wind would push the ship to the east, he ordered a new course of 036 degrees by gyrocompass to compensate. He estimated that the actual direction of the ship’s motion would then be 040 degrees true.

At about 6:00 p.m. on December 14, the Argo Merchant’s gyrocompass failed, and steering had to be accomplished by the magnetic compass. The ship had reached a location where the variation is 14 degrees, which meant 036 degrees by gyrocompass was equivalent to 050 degrees by magnetic compass. The captain ordered a course of 047 degrees magnetic. The ship was no longer being pushed to the east by the wind, because the wind had died down. At this point, the Argo Merchant should have been steering about 054 degrees by its magnetic compass, but it was actually steering 047 degrees. This 7-degree error was fatal.

The Argo Merchant was not equipped with modern electronic navigation equipment that would have accurately fixed its position at regular intervals. The ship was equipped for celestial navigation, but its officers failed to make effective use of this system.

Instead of passing four miles to the east of Nantucket lightship at 4:00 a.m. on December 15 as intended, the Argo Merchant passed perhaps twenty miles west of the lightship. The distance was such that the lightship did not show up on the ship’s radar. Mounted on the lightship is a powerful radio beacon with a range of two hundred miles. The Argo Merchant was equipped with a radio direction finder, a device designed to take bearings to radio beacons. If the radio direction finder had been used during the ship’s approach to the lightship, the error in the tanker’s navigation might have been discovered. A Fathometer was also installed on the Argo Merchant. This instrument measures the depth of water under the keel by bouncing a sound signal off the seafloor. The Fathometer was not turned on until it was too late to be of use.

Improper use of the magnetic compass placed the Argo Merchant about twenty-five miles west of its intended position. Failure to use the radio direction finder or the Fathometer in a timely manner meant the position error was not detected promptly. By 5:00 a.m. on December 15, the ship’s officers knew something was wrong but maintained their course and speed. One hour later, the Argo Merchant ran aground on Fishing Rip Shoal, thirty miles due north of Nantucket lightship.

Because the grounding occurred near the campuses of Woods Hole Oceanographic Institute and the University of Rhode Island, institutions that study the sea intensively, the resulting oil spill was very thoroughly researched. Scientists learned much about the behavior of an oil spill that helped them deal with bigger spills that followed. Even though the spill occurred near one of the most productive fishing grounds in the world, ecological damage was minimal and of short duration. Three major factors reduced the effects of the spill: Steady winds from the west pushed the oil out to sea, the oil did not sink and contaminate the seafloor, and the spill occurred during cold weather when the plants and animals of the sea are not very active.

When the tanker ran aground, thirty-eight people were aboard. Twenty-three of them were taken off the tanker by a U.S. Coast Guard vessel on December 15. The remaining fifteen people were evacuated by helicopter the next day as the weather worsened. None of the crew was injured.

The owners of the Argo Merchant were slow to respond to the grounding. If they had made arrangements immediately for tugs and barges, oil could have been pumped out of the ship. This would have caused it to refloat, and tugs could have towed it to a safe harbor. If such efforts had been conducted successfully, it is likely that little or no oil would have been spilled.

The Board of Investigation of the Republic of Liberia suggested that the grounding was intentional. The board believed that the owners wanted the ship wrecked so that they could collect on the ship’s insurance. Most analysts discount this theory.

By December 19, the U.S. Coast Guard estimated that 20 percent of the Argo Merchant’s cargo had leaked into the sea. At that time, the ship was still intact. On December 21, a bad storm caused the tanker to break in half, releasing another 20 percent of its cargo. The next day, the forward part of the wreck broke in half, and more oil was released. The bow section of the wreck began to drift with the current on December 29. A Coast Guard vessel shot holes in the bow section on December 31 to prevent it from drifting into shipping lanes. Ultimately, all the oil escaped into the sea.

Wind blowing from the west during most of December and January pushed the oil out into the open waters of the Atlantic Ocean. No oil from this spill was seen closer than fifteen miles from land. By December 31, 1976, the farthest edge of the spill extended about 140 miles southeast of the wreck. If winds had blown from the east, the oil would have fouled the coastline of Massachusetts and Rhode Island.

Burning can be an effective method of dealing with oil on the sea, as shown by the Torrey Canyon oil spill in 1967. Two attempts were made to set the oil from the Argo Merchant on fire, but neither succeeded. As the oil did not threaten any coastline, chemical dispersants were not used.

Up to 50 percent of an oil spill may evaporate into the atmosphere. There, the oil is consumed by a process called photooxidation. This process converts the oil, which is mostly carbon and hydrogen, into water and carbon dioxide. All surface water contains bacteria that feed on the oil; this process is called biodegradation. Sedimentation is a natural process in which oil attaches itself to solid particles of shell, clay, silt, and sand that are suspended in the water. These particles eventually fall to the seafloor and may remain there indefinitely. Studies of the seafloor near the wreck showed very little evidence of oil. Only very near the bow section was there significant oil on the seafloor. The natural processes of photooxidation and biodegradation are believed to have taken care of oil spilled by the Argo Merchant.

Marine life of all kinds can be severely affected by an oil spill. In the case of the Argo Merchant spill, there was evidence of this effect, but it was not as severe as in other spills such as the Exxon Valdez and the Amoco Cadiz. Marine mammals were not affected to any significant degree. Birds were affected more than mammals, but not severely. Herring gulls and great black-backed gulls were hardest hit. Black-legged kittiwakes were less affected. Oil-coated murres washed ashore on the islands of Nantucket and Martha’s Vineyard.

The fish eggs in the area of the spill were killed. Cod and pollock were the main species affected in this way. Plankton, the tiny animals and plants that drift about in the sea, were heavily contaminated in the spill zone. Plankton is the main food of many fish, so when fish eat oil-contaminated plankton, the fish become contaminated. In some cases, the fish may be able to excrete the oil contamination, but in other cases they may be sickened or killed by it.

Massachusetts governor Michael Dukakis asked President Gerald R. Ford to declare the state’s coastline a disaster area, and Cape Cod fishermen filed suits totaling $120 million against the tanker’s owners. A full-scale environmental disaster did not occur, but in July, 1977, government investigators estimated that the spill cost U.S. taxpayers $5.2 million. The ship itself was worth $3 million, and its cargo was insured for $2.3 million, thus the overall cost of the disaster was more than $10 million. Oil spills
Disasters;oil spills
Ecological disasters

• Cahill, Richard A. Disasters at Sea: Titanic to Exxon Valdez. Kings Point, N.Y.: American Merchant Marine Foundation, 1990. This second, shorter account of the grounding by Captain Cahill is less technical than his 1985 book.
• _______. Strandings and Their Causes. London: Fairplay, 1985. Captain Cahill, a graduate of the U.S. Merchant Marine Academy with forty years of experience at sea, brings the perspective of an expert to the analysis of the disaster. The book deals with the events leading up to the collision, not with the cleanup.
• Grose, Peter L., and James S. Mattson, eds. The Argo Merchant Oil Spill: A Preliminary Scientific Report. Boulder, Colo.: National Oceanic and Atmospheric Administration, 1977. Although much of the report is highly technical, the summary sections are quite readable. Twenty pages of color photographs and many detailed maps are included.
• Grove, Noel. “Sailing with the Supertankers.” National Geographic, July, 1978, 102-124. Written to accompany an article about the Amoco Cadiz grounding, this article provides very useful background information. Contains an excellent cutaway drawing of a large tanker as well as photographs of life aboard a tanker. An artist’s rendering shows the major oil trade routes of the world.
• Hooke, Norman. Modern Shipping Disasters, 1963-1987. London: Lloyd’s of London Press, 1989. An excellent general reference that provides a brief account of every merchant marine or naval ship lost between 1963 and 1987. Coverage of the Argo Merchant grounding is longer than most.

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