Mighty Vessels Ready to Help

BY AWAKE! WRITER IN FINLAND

SEA GULLS soar through the cloudless sky. The sun is burning. The air is filled with the mild aroma of coffee beans. Finally the hatches of the hold bang shut, sirens howl, and a heavily loaded cargo vessel laboriously sails off. A load of coffee beans has started on its way to Finland, a country of coffee lovers. A few weeks later, however, in the bitter cold of the winter, the vessel carrying these sacks of coffee beans is about to get stuck in the thick ice of the Baltic Sea. What can be done? There is no need to worry, for help is on the way. A mighty vessel appears on the horizon​—an icebreaker.

Breaking the Ice

Much of the world’s cargo travels by sea. Usually this presents no problem. But how can ships get to harbors when the sea is frozen? This is especially tricky in the busy Baltic Sea, which for many countries is the only passage to the open ocean. For example, during a severe winter, most of Finland’s harbors are blocked by ice, and its northernmost harbors may be surrounded by ice for up to six months. This has cost human lives.

In 1867, the crop harvest in northern and central Europe was poor. As none of the water passages to Finland were ice-free until May, there was no way to get relief supplies through until the ice melted. In the book Through Ice and Snow, sea captain Seppo Laurell says: “By that time some 110,000 people, or more than five per cent of the population [of Finland], had perished due to starvation.”

 Ice obstructs cargo traffic elsewhere too. In North America this is a common problem on the Great Lakes, on the St. Lawrence River, and along the Canadian coast. The Arctic and Antarctic areas are even more difficult to tackle during the icy winter. There the average thickness of ice is six to ten feet [2–3 meters].

Early Attempts at Breaking Channels Through the Ice

In the era of sailing ships, the ice was an almost invincible obstacle. After the first steel-hulled steamships appeared, the situation improved. If the cargo ship was strong enough, it could pass through thin ice by itself. However, such ships were limited, even though some of them were specifically reinforced for ice.

Building icebreakers provided a solution. The world’s first icebreaker is said to have been the City Ice Boat I, built in the United States in 1837. In Europe the Eisbrecher was built in Hamburg, Germany, in 1871. Experience soon taught what kind of vessels coped best with ice, and at the turn of the 20th century, certain fundamental designs had already been established. *

Floating Iron Giants

What is it like when a ship gets trapped in ice? “The ship shivers as if it had a high fever,” relates a  sailor. The hull of an icebreaker has to withstand a pressure many times greater than the hull of a merchant ship. “Crashing into an ice bank is about the same as driving onto a beach with a motorboat,” says a worker on an icebreaker. The steel plates in the bow may be well over one inch thick [3 cm]​—on polar icebreakers even up to two inches thick [5 cm]—​and the body of the ship has specific ice-reinforcement ribs in addition to the regular ones. How strong are such ships? During World War II, when the icebreaker Tarmo was hit by a bomb, the navigating deck and most of the cabins were destroyed, but the hull did not even spring a leak.

The shape of the hull is crucial to an ice-breaking vessel. Often the most difficult task is not actually breaking the ice but pushing the broken pieces away. Many icebreakers have a somewhat shallow bow, shaped like a spoon. The vessel breaks the ice with its mass and pushes the blocks to the sides and below. The shape of the hull is carefully designed to minimize friction between the body of the vessel and the ice. In addition, the body is covered with stainless steel or an extremely smooth and durable epoxy paint.

How are these iron giants powered? Gone are the days when sweating men had to shovel coal for the boiler in the engine room. Modern icebreakers are diesel-electric, and their shaft output is similar to that of medium-sized tankers. To equip icebreakers to operate in polar regions without fear of running out of fuel, some are powered by nuclear reactors.

Unique Specifications

If a rowboat gets stuck in the mud, the rower may free it by rocking the boat from side to side. The same principle is applied to icebreakers. In their case, however, it would not be enough even to have the whole crew of about 30 men rush from one side of the ship to the other. The rocking is produced by a special heeling system​—water is transferred back and forth between a huge water tank in one side of the hull and another tank in the other side. Why, in some cases, this heeling is accomplished in as little as 15 seconds! The very thought of such swaying is enough to turn a landlubber’s face green. Sailors, of course, are in a class of their own.

By the end of the 19th century, someone had thought of placing a propeller in the bow. The propeller’s movement produced a stream of water that lessened friction and pushed the ice slush out of the way. Some modern icebreakers have two propellers in the stern and one or two in the bow. In many icebreakers, however, the protruding bow propeller has been replaced by an air-bubbler system. Underwater nozzles along the hull release large volumes of compressed air into the water below the ice, causing powerful bubbling in the water, which reduces friction.

A Look at the Horizon

The warm sun of spring does what all nine mighty icebreakers of Finland fail to do​—it breaks the icy chains around all the harbors, even in the northernmost parts of the land. The icebreakers return to their home port, and this means an easy summer for the crew. The expensive, specialty vessels will be idle for several months because their specific construction makes them poorly suited for regular navigation in open water.

However, there is a new generation of vessels. These multipurpose icebreakers operate as conventional icebreakers in the winter, but during the open-water season, they can be used for such things as cable laying, research operations, and maintenance of offshore oil rigs. One such vessel, the Botnica, which was built in 1998 for use by the Finnish Maritime Administration, has two azimuth podded drives that rotate 360 degrees and thus operate not only as propellers but also as rudders. The drives make the vessel amazingly maneuverable. This design has been applied to new cruise liners as well.

In the wake of advancing ice-breaking techniques, an idea for a new kind of cargo vessel has come up. When moving forward, the new vessel would plow through the waves in the usual manner. The stern, however, would be used in breaking ice. This “double-acting tanker” would be especially useful in polar areas, where the help of icebreakers is often out of reach. The vessel could cut its own channel through the ice by moving backward.

In the meantime, Finland urgently needs its coffee. The icebreaker spoken of in the opening paragraph of this article has broken the coffee freighter free and is now towing it. The captain of the icebreaker leans calmly on the rail. He then turns toward the navigating bridge. It is time for a cup of hot coffee.

[Footnote]

[Picture on page 25]

The icebreaker “Otso” making a passage

[Credit Line]

Finnish Maritime Administration

[Picture on page 25]

Winter steamer stuck in the ice​—about 1890

[Credit Line]

Museovirasto

[Picture on page 26]

The nuclear-powered “Taymyr”

[Credit Line]

Kværner Masa-Yards

[Picture on page 26]

Multipurpose icebreakers can also be used in laying cables and pipes

[Credit Line]

Finnish Maritime Administration

[Picture on page 26]

The “Botnica”

[Credit Line]

Finnish Maritime Administration