Master of 30.000 Horsepower
Interview with our Chief Engineer
Below the car deck, in a two-storey hall, is the engine room. it propels the Norröna’s 164 meters. Here four mighty six cylinder MaK-engines grind out a terrible deafening roar. And chief engineer Ólavur Gunnarson is the master of the 30,000 horsepower the engines are capable of producing. He and the 12-man engine crew are proud of their machinery and are very careful to keep it clean, tidy and running smoothly.
Ólavur leads us through the infernal noise from the engine room into the control room where the horsepower is tamed, and where hearing protection is no longer required. This is where the engineers have a complete overview of how the machinery is running. There are a lot of sensors on the engines, which constantly monitor specific functions. They will sound one of the 200 alarms in the control room, if something is not running as it should.
The MaK 43 model engines are fitted with pistons on each of the six cylinders with a diameter of 43 centimeters, and normally run at 500 rpm. When engine power is transferred to the pair of giant propellers at the Norröna’s stern, the momentum is geared down to 115 rpm – which suits the two 5.2 meter high and 9 tonnes propellers best. With four engines, each producing 7,500 horsepower – combined 30,000 horsepower, or 21,600 kilowatts – you could compare the ship to a large power plant, at least on a Faroese scale.
The Norröna’s power equals half the output of the only major thermal power plant on the Faroes, Sundsverkið, located just outside the capital Tórshavn. The engineers have calculated that the Norröna’s power equals approximately 40% of total thermal energy production in the Faroes on the topic of energy production, the Norröna is fitted with a shaft generator, which produces the electricity required while the ship sails. When the Norröna is in port, auxiliary engines are turned on. The ship has three auxiliary engines, also MaK, but model M20; the figure indicates the size of the pistons. The auxiliary engines are two 9-cylinder engines, which reach 1800 kilowatt, and one 6-cylinder, which generates 1200 kilowatts. The engines are launched as needed, whether to generate electricity for the vessel or to boost the main propulsion engines.
The main engines are far from always in use. Ólavur Gunnarson tells us:
“It depends on what service the captain wants. If we stay below 18 knots, we don’t need all four engines, so we often run on only three, and sometimes only two.” The engines run on heavy fuel, which the Norröna bunkers in Danish port. This viscous mass has to be warmed up to 50 degrees Celsius to enable pumping. The Norröna is equipped with separators and filters, which treat the oil and clean out impurities before it is injected into the engine. When the fuel comes into contact with the cylindrical chamber, it is heated to 133 degrees Celsius and atomized under very high pressure – 470 bars – to ensure that the combustion is as clean as possible.
Respect for the environment
If the Norröna ran on full power, around 22 knots, its oil consumption would be 100 tonnes a day. But this is not the case. Under normal circumstances, the Norröna uses 320 tonnes a week in low season, and 450 tonnes per week during the summer peak season, when the ship sails further and faster every week. Oil consumption is constantly monitored, both to achieve the most efficient operation possible and to meet the requirements of as low emissions into the atmosphere as possible. “We always monitor our energy use. The company has set up a committee, made up of members from both our onboard crew and staff on land. it continuously develops new ways to reduce oil consumption and environmental impact”, Ólavur Gunnarson says.
Not only the ship’s propulsion is managed and controlled from the control room next to the noisy machines in the bottom of the ship, the engineers are also responsible for the ship’s own waterworks. “We can produce clean water onboard the Norröna. We take in seawater, pump it through a special so-called reversible osmosis plant and out the other end comes the finest drinking water when we add a bit of chlorine and other necessary purification agents. The water system is, however, only in use during peak season, when we have many guests, and the stay in port is brief. otherwise we take in water in Tórshavn. Faroese water is of a very high quality and it is cheap. it is not worthwhile having the ship’s water system running, if it can be avoided”. The engine staff is, of course, also responsible for the waste water system; which is in place to ensure that waste water is purified to the standards required before it is released into the ocean. There is a boiler in the engine room for heating the ship, but it is not in use while sailing. Instead heat from the engine exhaust is used to heat both the water in the taps and the indoor air in the cold seasons.