Electricity on the Deep Blue Sea

During the celebration of National Maritime Day, our thoughts turn to the marine industry. Many Americans have romantic ideas about ships—yachts or sailboats lilting gently on the waves beneath a warm sun.  Look a little deeper at ships, however, and you will come to appreciate the wonder of their logistics. 

Large ships are comparable to a floating city. Many privileges that people typically enjoy on land are also available on a ship. Just like in your typical city, there are amenities aboard a ship. Life carries on as usual – people eat, exercise, enjoy entertainment, and use plenty of electricity.

You may be wondering how you get power when you are many miles out to sea? A prime mover and an alternator work together to generate shipboard power. Ships use alternating current generators. The generator is made of stationary conductor sets wound in coils with iron ore core. This is called the stator. A rotor, or rotating magnet that turns inside the stator, produces a magnetic field. When the magnetic field cuts across the conductor, it will generate an induced electro-magnetic force as the mechanical input turns the rotor. The resulting electricity is dispersed across the ship using a power distributor.

The ship has an emergency power system, or standby system, just in case the main power generation system fails. The emergency power supply ensures the continuous operation of the essential systems and machinery aboard the ship.  Batteries or emergency generators, at times a combination of the two, typically supply power.

The rating of the ship’s emergency power supply must ensure that the following essential systems are working, including the following:

• Steering system
• Emergency bilge and fire pumps
• Watertight doors
• Fire fighting system
• Navigation and emergency lights
• Communication and alarm system

The basic systems must remain operational to ensure the safety of the ship’s passengers until the regular power supply can be restored.