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November 14, 1989
Tankers full of trouble

Double-Bottom Debate
Two-layer skins can help keep oil aboard

ABOARD THE ARCO ANCHORAGE — Each time it cruises into Washington's Strait of Juan de Fuca, this ship offers up a testimonial on the value of double-layered bottoms on oil tankers.

Each time the Japanese tanker Matsukaze enters these waters, it provides the "Amen."

Together, the two ships make a compelling case for a proposal that all newly constructed tankers be required to have double bottoms.

Each ship went aground on the north shore of Washington's Olympic Peninsula in separate accidents within the past five years. The accidents occurred only 17 miles apart, and the damage to the two tankers was remarkably similar: In each case, a large rock gouged the ship's steel bottom, cracking it open.

But the outcomes of the two accidents were startlingly different:

The Arco Anchorage, which was traveling at less than 2 knots when it drifted aground in 1985, spilled 239,000 gallons of crude oil into the harbor at Port Angeles — the largest spill in Washington state history.

The Matsukaze, which hit a nearby beach violently at 14 knots in 1988, lost not a drop of its cargo of oil.

Why the difference?

The Matsukaze has a double bottom. The Arco Anchorage does not.

All that separates oil from ocean for the Arco Anchorage is a layer of high-strength steel about an inch and a half thick. On the smaller Matsukaze, conversely, the cargo is contained by one layer of steel, then a space of about 10 feet, then another steel layer.

The Arco Anchorage is 120,000 deadweight tons, while the Matsukaze is 16,000, but size made no difference in the outcome of the groundings.

The Arco Anchorage's toll: $13 million for cleanup, $500,000 in ship repairs and as many as 4,000 dead birds.

The Matsukaze's: A $213,000 repair bill.

Indeed, strong support for double bottoms. So what happened as a result?

Virtually nothing.

The Coast Guard investigation of the Arco Anchorage spill mentioned just once, in parentheses, that the ship does not have a double bottom. No conclusions were drawn. And no Coast Guard report highlighted how a double bottom made a difference in these two accidents.

The National Transportation Safety Board did not even study the groundings because the damage to each ship was below the $500,000 threshold for an NTSB investigation.

And Congress, which holds the authority to require double hulls on U.S. ships, continued to submit to the powerful oil-industry lobby, making no changes in the law.

This summer — only after the grounding of the tanker Exxon Valdez, the largest spill in U.S. history — did Congress finally begin to address the need for double bottoms. However, even now, many predict that the oil lobby will succeed in killing or watering down any requirements.

The House last week passed a version of an oil-safety bill that would require all tankers that come into U.S. ports to have double bottoms within seven years and double hulls within 15 years. But the Senate had earlier voted down such a provision, and most observers expect the requirement will not survive in the bill that emerges from the House-Senate conference committee early next year.

Instead, according to Rep. Norm Dicks, D-Bremerton, what is likely is a provision that gives the Coast Guard and the Department of Transportation six months to a year to study the issue and if they choose, to make a case that double bottoms and hulls are unnecessary.


Not that the issue hasn't been studied before. Other reports that have gathered dust since the 1970s bolster the case made by the Arco Anchorage and Matsukaze groundings:

• A 1972 Coast Guard report says double bottoms would have prevented spills in 12 of 13 analyzed tanker accidents. A double bottom less than half the thickness of the Matsukaze's would have stopped oil from spilling in all 12 cases; in fact, nine tanker bottoms were penetrated only 1 1/2 feet or less.

• A 1973 Coast Guard report says standard double bottoms would have prevented spills in 27 of the 30 U.S. tanker groundings between 1969 and 1973. A total of 3 million gallons of oil and fuel spilled in those 27 groundings.

• A 1974 study done by Battelle Laboratories for the Coast Guard says barges with double bottoms or double sides were punctured all the way through in only 14 of 268 accidents (5 percent), while single-hulled barges were punctured 295 of 311 times (95 percent). The study says double hulls, which have double bottoms and double sides, would have a "significant and dramatic" ability to prevent oil-barge spills.

• A 1974 NTSB investigation of the March 1973 grounding of the tanker Hillyer Brown at Cold Bay, Alaska, says a double bottom would have prevented the 200,000-gallon spill. The report concluded that double bottoms would prevent spills in minor groundings and reduce the size of spills in more severe cases.

"Almost without exception, if a ship has a double bottom, you don't have a spill, and if it doesn't have a double bottom, you do. It doesn't take Dick Tracy to figure that out," says Seattle Coast Guard investigator Lt. Cmdr. Larry Lockwood.

What was the result of these studies?

The Coast Guard replied to the NTSB report on the Hillyer Brown, saying it concurred with the conclusion that double bottoms seem to prevent spills.

But no major studies of double- and single-bottom accidents were done from that point on, and by 1978, a double-bottom requirement had been defeated in international negotiations. Today, nowhere in the world are oil tankers or oil barges required to have double bottoms.

Consequently, only 419 of the world's 3,500 oil tankers — about 12 percent — have full or nearly full double bottoms.

In addition, most tankers that carry combinations of oil and other products such as chemicals and grain have full or partial double bottoms.

Only two of the 19 tankers that regularly visit Washington waters have full or nearly full double bottoms. Only 41 of the 211 (19 percent) tankers that visited the state at least once in the past two years have them.

Arthur McKenzie, a tanker consultant who has studied the issue for decades, says emphatically that no other single improvement would do as much to curb spills as a requirement for double hulls on all newly constructed tankers.

McKenzie wants double hulls, rather than double bottoms, because they have double sides that will protect a ship's flanks from collisions. They cost more, because a double side must be very deep to absorb the violent force of a ship collision.

"Most owners wouldn't build them that way unless they were damned sure they were going to be required," McKenzie said.


While tanker builders have shunned double bottoms, most other ships have them.

Freighters have double bottoms to provide spaces for ballast water, which is loaded into a ship to keep the propeller in the water and the ship stable after cargo has been unloaded. Tankers have ballast tanks next to cargo tanks, and in some cases cargo tanks are used for ballast water.

Laws and international treaties require tankers carrying hazardous chemicals, liquid natural gas and propane to have full double bottoms and huge double sides to help contain their poisonous and explosive cargoes.

Why not a similar requirement for tankers carrying crude oil, another poisonous and explosive substance?

Retired Coast Guard Rear Adm. William Benkert, a participant in international conventions on the subject, explains it thus:

"Chemicals are harmful to human beings. We have not seen fit to approach crude oil, or other types of petroleum products, in the same vein because the risk isn't there for people. The risk might be there from a pollution sense, killing some fish and otters, and I can say from a cosmetic sense. But certainly that doesn't have the same effect as a spill of chlorine."

Benkert headed a U.S. Coast Guard delegation that failed to persuade an international convention to approve a double-bottom requirement for tankers in 1978. The oil industry defeated all efforts in the 1970s to require double bottoms, and the issue remained dormant until this year with the Exxon Valdez spill.

Meanwhile, the oil industry has its own studies to counter the double-bottom clamor. One report done for the shipbuilding division of the Bethlehem Steel Corp. in 1973 said double bottoms would be effective in only 37 percent of oil spills.

Here are some of the issues raised by the oil industry in opposition to a double-bottom requirement:

• Salvage. Many in the industry insist that flooded double bottoms make ships more difficult to salvage. The contention is that when a double bottom is split open, it will fill with water — which weighs more than oil — and make the ship much heavier.

Tom Wyman, a spokesman for Chevron Shipping Co., says oil companies worry that a stranded double-bottom tanker with its broken bottom full of sea water might be too heavy to move, leaving the ship exposed to wind or waves for days while salvagers figure out how to rescue it. It could sink and lives would be lost, he says.

Federal studies indicate that worry is probably misplaced. The NTSB in 1974 said technology had overcome all salvage difficulties that might be presented by double bottoms. A 1977 U.S. Maritime Administration study of groundings found that no ships with double bottoms sank.

Capt. Charles Bartholomew, supervisor of Navy salvage, says that while a double bottom might create some challenges to salvagers, "there should be no special problems that a capable salvage engineer could not solve."

In fact, J.H. "Mick" Leitz, a Portland salvage contractor who refloated both the double-bottomed Matsukaze and the single-bottomed Exxon Valdez, says "in most cases a double bottom would make a ship easier to salvage."

• Instability. The oil industry argues that a flooded double bottom can make a ship less stable and in some cases — such as that of the Exxon Valdez, which was stuck on a rock — could cause a ship to tip over.

Here, Leitz, one of the world's foremost salvage experts, agrees with the industry people. He speculates that a flooded double bottom on the Exxon Valdez could have caused it to slide off its perch. Then, he says, it likely would have spilled more of its remaining cargo of 42 million gallons of crude oil.

"The real ticking time bomb up there wasn't what had already spilled out of the ship. The real ticking time bomb was what was still sitting there in the ship," Leitz says. "If it had had double bottoms, it would have probably made the situation a lot more serious."

However, a Coast Guard study released to Congress in May says that with a double bottom, the Exxon Valdez might have spilled 25 percent to 60 percent less oil.

Coast Guard Vice Adm. Clyde Robbins, coordinator of the cleanup, buys that assessment.

"To my way of thinking, this spill would have been a lot less if the vessel had had a double bottom," Robbins says. "I can't believe all the tanks would have been breached."

A 1975 Office of Technology Assessment report says single-bottom ships sink at a higher rate than double-bottom ships.

• Fire danger. Leitz says a tanker's inner tanks might crack and drip crude oil into the void between the ship's first and second bottoms. Fumes could collect there and explode. Salvagers, while cutting into a damaged ship, also could touch off an explosion in a double-bottom space contaminated with fumes.

The 1975 Office of Technology Assessment report also addressed that question. It says double bottoms wouldn't be much different from ballast tanks, which are already in use in tankers. Ballast tanks are next to oil tanks and are empty when the oil tanks are full, so they, too, could be explosive if oil leaked into them.

In fact, the ballast tanks have more sources of ignition inside — pumps and cleaning nozzles — than double bottoms do.

• Crew convenience. Tanker crews generally hate double bottoms because they have to crawl around inside them to do inspections. The complaint is rarely made public, but it may be one of the keys to the argument against double bottoms.

On some ships, the space between the bottoms is so small a crew member cannot stand inside it, and must crawl through a maze a small holes to get through it. The holes provide the only access through the wide steel rafters that form a ship's frame.

Crew members carry lights and sometimes wear breathing masks, but if they get lost or drop the light, they are in serious trouble. And all the time, they are underneath 90 feet of crude oil. A leak above them could result in explosive and deadly fumes.

Entering a double bottom is a nightmare, says Jeff Portillo, the Arco Anchorage's chief mate.

"The only time you can get in to inspect them is when they are empty, and the only time they are empty is when we are fully loaded with crude oil," he said.

"The guy that advocates double bottoms hasn't hunkered his way through them," says Paul Preziose, chief engineer on the Arco Anchorage.

• Cost. Although many in the oil industry deny it, cost has been a major issue in the debate.

Wyman, the Chevron spokesman, insists that oil companies wouldn't resist paying more for double bottoms if they substantially enhanced safety.

"An increased shipbuilding cost of 8 percent or more, that's not going to break a company, particularly if it allows us to sleep more easily at night," he says.

But most experts disagree with that characterization.

Estimates of the increased cost of building a tanker with a two-layered exterior range from 5 percent to 30 percent, depending on the tanker's size, where it is built and whether it has a double bottom or a full double hull.

Edward Deakin, director of the Institute of Petroleum Accounting at the University of North Texas, says oil companies do worry about the added costs — even though transportation of oil is only a small part of consumers' price at the pump. Taxes and oil-field development account for much more of that pump price.

"Still, any time you tack even a few pennies onto the price of a barrel of oil, you are adding billions to an oil company's costs," Deakin says. "So they are tempted to cut the cost of tanker operations all the time."

Besides the manufacturing costs, double bottoms and double sides reduce the cargo-carrying capacity of tankers, cutting further into the bottom line.


Clearly, the industry's arguments are debatable. Yet - bolstered by millions of dollars in political contributions — they've been enough to stave off all efforts to require double bottoms.

Meanwhile, the single-bottomed Arco Anchorage makes its voyage every eight days into the Strait of Juan de Fuca, sailing past the place where it spilled enough oil to fill 28 tanker trucks.

Some days, when the refinery dock at Cherry Point is too busy and the ship has to wait, it pulls into Port Angeles Harbor as it did on the day of the spill.

There are still reminders in the harbor, the most noticeable being the 10,000 feet of oil-containment booms ready to go. The cleanup of the '85 spill was delayed for several hours because there weren't enough booms.

Larry Glenn, the city's fire chief, remembers the hellish day as if it were yesterday. He says Arco eventually did an excellent job cleaning up the oil, but he has one wish:

"I think double bottoms are a necessity. The only thing that keeps double bottoms from occurring is the cost."

Looking out his window at the bay, Glenn reflects on the fact that that he and others were helpless against the spreading slick. He can only wonder at one more than 40 times larger, such as the Exxon Valdez disaster.

The fire chief says that as he looks out at the single-bottomed oil tankers sailing by every day, he thinks of a big bear.

"A bear is safe out there in a natural area," he says. "But once it gets into your front room, it's not so much fun."

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