YOU might say that Richard Cahill foresaw the sinking of the ferry Estonia last week in the Baltic.
In ``Disasters at Sea,'' a 1990 book analyzing major shipping mishaps, Mr. Cahill included a chapter entitled, ``The RO-RO, an Unsafe Design.''
Now Cahill, a ship captain who lives in Austin, Texas, predicts in an interview that ``there will be more'' sinkings because he considers the design of the ships, called roll-on, roll-off, or RO-RO, inherently inadequate because there are no watertight compartments to help keep the boat afloat in an emergency.
``All RO-ROs without internal subdivision are unsafe,'' Cahill says.
At a meeting Dec. 5-9 the Safety Committee of the International Maritime Organization (IMO) will consider the safety of the 4,500 RO-RO vessels around the world.
``It is intended that this [meeting] will take into account both construction and operational features,'' says Roger Kohn, a spokesman for the IMO, a shipping-industry group based in London.
``The aim of all of this is to really open up the whole issue of RO-RO safety,'' he adds, ``not on a piecemeal basis, but looking at the whole question.''
The Estonia went down Sept. 28 in a Baltic Sea storm, killing more than 900 people. Although it is still early in the investigation of the disaster, there is evidence that the vessel's bow doors failed.
This week maritime authorities in Finland and Sweden ordered that the bow doors of Baltic Sea ferries be welded shut, at least until the completion of the Estonia investigation.
The US's RO-RO fleet
The United States has a small fleet of RO-RO ferries. Most ply relatively narrow bodies of water, such as Long Island Sound or the channel between Staten Island and Manhattan in New York City. Also, some ocean-going ferries sail between California and Hawaii, and between Portland, Maine, and Nova Scotia. All of these ferries are regularly examined by the US Coast Guard.
``We certainly wait with interest [for] the IMO report,'' says Peter Popko, assistant chief of the Coast Guard's Merchant Vessel Inspection and Documentation Division in Washington.
In Portland, Maine, Coast Guard Lt. Steve Wischmann says that, as a result of the Estonia sinking, ``we are likely to look at certain systems more closely as we learn what went wrong.''
This is not the first time the IMO has looked at the issue of RO-RO safety. In 1988, the organization tightened its standards for the stability of the vessels. The new standards were to be phased in over 11 years, since the IMO did not want to burden ferry owners with the cost of massive conversion. In addition, the IMO points out, there would not be enough shipyard capacity for sudden changes.
The first improvements in safety for the oldest of the ships was supposed to take place last Saturday. The Estonia, built in 1980, was not due for improvements for several years, according to Mr. Kohn.
The IMO changes followed a 1987 shipping mishap when the Herald of Free Enterprise capsized off Zeebruge, Belgium, killing 200 people. An inquiry found that the bow doors had not been safely closed, allowing water to flood the car deck. As the water sloshed around, the boat lost stability and ultimately capsized.
Before the Estonia departed on its overnight trip to Sweden last week, Swedish inspectors had noted some weakness in the door seals. The head of the Swedish maritime safety division has already indicated he believes the bow door ``had a break and was exposed to the excessive forces of the sea.''
On Oct. 2, investigators located the ship in about 250 feet of water. Underwater robots filmed the wreck.
On Oct. 3, investigators who reviewed the video tape said the locks on the front of the cargo door had failed. As a result, the cargo door was torn off by the waves. The video also showed a problem with the inner bow door, which doubles as a ramp. The video showed a gap of about three feet along the top edge of the ramp. This was wide enough to allow in the tons of water that ultimately destabilized the vessel.
As the Estonia started to pound into 18-foot waves, ``What could have started off as a trickle could come spurting through in a stream,'' Cahill says. ``It was not discovered immediately, and by then it was too much to handle.''
Cahill, who has been a visiting professor at the United States Merchant Marine Academy in Kings Point, N.Y., believes the captain should not have sailed once he had learned the gaskets were leaking slightly, but should have gotten the gaskets repaired.
Once water gets in, the boats capsize relatively easily owing to the ``free surface effect.'' This is what happens when a metal ice-cube tray is filled with water. Water easily sloshes over the sides of the tray until the compartments are inserted.
Other RO-RO sinkings
On the RO-ROs, there are no compartments or watertight bulkheads to impede the movement of water, since the whole idea of the ship is to move cars and trucks on and off the vessel quickly. The incoming water destabilizes the vessel as tons of water shift. Once the vessel starts to heel over, the trucks and cars also begin to shift, compounding the problem.
Since RO-ROs have been in service, the best known mishaps involved the Princess Victoria, which lost 133 people in 1953; the Zenobia, which sank without loss of life in 1980; the Speedlink Vanguard, which went down in 1982 after colliding with another RO-RO, the European Gateway, off Harwich, England, with six deaths; and the Herald of Free Enterprise in 1987.
In recent years there have been some attempts to improve the design. A RO-RO that runs from California to Hawaii has bulkheads built along the sides of the hull. Normally these compartments carry fuel and water. ``If the ship gets water inside, this area remains intact and the ship remains very stable,'' says Cahill.
In Australia, a few RO-ROs have been built like catamarans on pontoons. ``They are more expensive to build, and they tend to be smaller, but this is the ideal design,'' he adds.