Power generation all at sea

Chief electrical officer of the Pacific Star, Roland Maxwell in the ship’s large switchboard area. The main control room of the Pacific Star which is manned by engineers 24/7.

Editor Lynnaire Johnston recently took a South Pacific cruise and learned that electricity-wise, a ship is the equivalent of a
small town.
One of the stupidest questions passengers on a cruise ship ask is, “Does the ship generate its own electricity?” Seriously. Passengers seem to think ships drag a huge cable behind them as they plough the ocean waves.
You’ll be surprised then to learn that’s not the case. A ship the size of P&O’s Pacific Star (35,000 tonnes gross) in fact generates enough electricity to power a town the size of Masterton.
Chief electrical officer Roland Maxwell (read more about Roland on page 16), describes Pacific Star as “having an interesting and well-optioned power generation system”.

Generation and main switchboard
The ship’s electrical generation system consists of five 2500Kw, 440v, 60hz alternators. Three (referred to as auxiliary diesel generators) are driven by Man B&W 16U2HLH-4 diesel engines and two (referred to as shaft alternators) are driven by power take off’s (gearboxes) off the main propeller shafts which are powered by two Sulzer 7RND68M, slow constant speed main diesel propulsion engines, rated at 12000 B.H.P each.
Ahead and astern thrust is achieved through hydraulically operated variable pitch propellers. 
The main switchboard bus is configured for two modes of operation which can be switched via the automation or by a manual intervention.
When the vessel is in port or maneuvering, a minimum of two diesel generators supply the main bus with the bus coupling closed.
In this mode of operation and with the main engines running, the shaft alternators are available to independently power the bow thruster motor (1100 Kw) and stern thruster motor (950 Kw).
The unique method of starting each of these large motors off load and direct on line is achieved by removing the excitation to the shaft alternator, closing the motor breaker to the shaft alternator breaker and then re-instating the excitation, which ramps the motor up with a return of the generated voltage.
Chewing through fuel
When the vessel is fully away to sea there is no further requirement for the thrusters. The main bus coupling breaker is opened leaving one diesel generator supplying each side of the switchboard. Although they have no ability to load share, the shaft alternators are synchronized and closed to each side of the open bus and the diesel generators are then shut down following the load transfer.
This leaves just the two main engines supplying propulsion and approximately four megawatts of generated power for the vessel’s many power and lighting requirements.
At cruising speed the main engines burn a combined total of approximately 80 tons of heavy fuel per day. (Our 12-day cruise chewed through 796 tonnes or 812,245 litres of fuel. The 1074 passengers also drank 18,300 bottles of beer, but let’s not go there!)
The diesel generators burn a combined total of 16 tons of a lighter grade fuel per day.
Using the main engines to drive the shaft alternators results in a significant saving in fuel, lubricating oil and running hours to the diesel generators.
Roland assures us that complete black outs are rare. He says, “Should the main switchboard go into an overload situation, our first line of defense is the automatic preferential tripping of non-essential loads, eg galleys, laundry and air-conditioning. Should we experience a complete loss of power to the main switchboard then the emergency (transitional) batteries will hold emergency lighting and fire doors for a minimum of 30 minutes, although generally the automation will have started and closed the emergency generator (300Kw) to the emergency switchboard within about 15 seconds.”
The emergency switchboard supplies such critical equipment as water-tight doors, navigation equipment, steering, fire and bilge pumps along with limited lighting and of course enough services to enable a restart of a diesel generator for the restoration of the main switchboard.

Passenger perspective
Most passengers, naturally enough, don’t give a moment’s thought to how the ship is powered, what makes the lights come on, how their dinner is cooked, or how the beer keeps cold. By way of demonstrating how dependent the ship is on the hard work of Roland and his team, one person is employed full-time merely to change light bulbs. (The ship chews through thousands of fluorescent lamps and as spent bulbs are deemed to be hazardous waste there are strict procedures for their disposal.)
Roland runs a crew of 10, some of whom sign on for nine to 11 months at a stretch. That’s not nine months of five-day weeks, but seven-day weeks. (The captain described this as “draconian” but I’m not at all sure he’d want to be quoted.) One 2nd engineer we met worked in the control room four hours on and eight hours off on a continuous rotation.

Rules and regs
Naturally, ships today are subject to an almost infinite number of rules, regulations, policies and procedures. The Pacific Star is no exception.
Roland says, “The main standards have many specific parts relating to the electrical systems that I’m responsible for to ensure we comply in respect of equipment, maintenance and procedures. The vessel is regularly surveyed and audited on these standards.”
The standards include: SOLAS (Safety Of Life At Sea Convention), IMO (International Maritime Organization), MARPOL (Marine Pollution), ISM (International Safety Management), ISO 14001 (International Standards Organization), MCA (United Kingdom Marine And Coast-guard Agency),
USPH (United States Public Health), Lloyds Register (Electrical Engineering Rules And Regulations For The Classification Of Ships) and of course, P&O and Princess Cruises’ own Fleet Regulations.
Roland says the ship also uses an internationally known and recognized database “AMOS” for all maintenance and purchasing. “This comprehensive system replicates our shore office and covers all aspects of our planned maintenance, stores and purchasing system,” he says.
History and information contained within this system is used to ensure the ship complies with all the regulations mentioned above.
Safety is always paramount on board ship. There are training programmes galore and weekly emergency drills, each rehearsing a different scenario such as fire or running aground. Scheduled maintenance involves testing the emergency equipment.
Roland says the entire electrical team continuously undergoes training both onboard and ashore, which includes firefighting training.

Anything with a wire
“Included within our charge of maintenance and repair tasks is anything that has a wire. That’s the satellite navigation equipment, internal communication systems, the cabin televisions, the electronics on the bridge – echo sounder, GPS, radar etc – the lighting and sound equipment for the stage, the generation and propulsion, the engine room systems, the ovens and fryers in the stainless-steel lined galley and even the elevators.”
Now in service for 25-years, the Pacific Star has recently been sold and leaves the P&O fleet next March. She will be replaced by the larger, high voltage Pacific Dawn. In the meantime, for Roland and his team, it’s business as usual. As far as he’s concerned keeping up-to-date with routine maintenance is all part and parcel of a safe and professionally run ship.