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I'm no expert on "propulsion problems" but if you compare the original and revised itineraries the obvious intent by Princess is saving fuel. Now I trust that Princess (or any other cruise line) would immediately take out of service a ship with engine room issues that could even remotely compromise safety or integrity. So my guess in this case is that the only effect the current ongoing problem has is on fuel economy. Which is why Rotterdam was scratched because of the redundant out-and-back on the North Sea from Southampton. (And this call would have always been at risk if there was even the slightest delay leaving Southampton and/or a forecast of poor weather on the approach).

 

For the rest of the cruise I personally would exchange Vigo and the Azores straight up for Zebrugge and Bermuda anytime; the $100 OBC is a nice bonus. Though I concede those who had already made arrangements onshore for the rescheduled port days will feel otherwise.

By Ben Lyons, Cruise Critic contributor

Diesel ElectricEven though many ships are still built with conventional diesel plans, almost all new cruise ships (such as Celebrity's Solstice Class or Carnival's original Destiny Class) feature some form of "diesel electric" propulsion. On these ships, the main engines aren't connected to the propeller shafts; instead, the main engines are directly connected to large generators with one job: producing electricity. The electricity they produce is sent to electric motors, which then power and turn the propellers.

The primary advantage of diesel electric systems is efficiency; they allow the main engines to operate near their most efficient speed regardless of whether the ship is moving at 5 knots or 20 knots.

Getting the Terminology Straight

Admittedly, the technical vocabulary can be a bit confusing. For the purpose of this article, "main engines" refer to those engines that produce the vast power to move the ship. On conventional, or direct drive, diesel vessels, these engines are connected to the propeller shaft; on diesel electric ships, the main engines are connected to the main generators.

Furthermore, "engine" and "motor" are not interchangeable. Engines rely on fuel and ignition and can help generate electricity. Motors rely on electricity to make something move. Propulsion motors, therefore, take the electricity produced by the engines and use it to make the propellers turn.

It's all About the PowerAs we've seen in recent cruise-ship troubles, losing electrical power can be devastating. The main engines and even the generators themselves require electricity to keep going. Electrically driven pumps take in cold seawater from the ocean to help cool the engines; electrical pumps take fuel from the fuel tanks and supply it to the engine. Electrical power is critical to many operating functions, and without it, the ship comes to a halt.

Of course, the production of electricity is vital to all aspects of a ship's operation. Large equipment (such as the bow thrusters, or, in the case of diesel electric ships, the actual propulsion motor) requires high-voltage electricity. For smaller machinery, such as lights in your cabin or the equipment in the galley, the electricity goes through a transformer and is stepped down into a more useable, lower voltage -- such as 110V.

To distribute the electrical power, large cables snake through the ship. Hundreds of miles of cables carry power from the generators to switchboards and eventually through passageways, cabins and public rooms.

Cabling can be a weak point in a ship's distribution system. Even ships with two engine rooms can suffer power failure if the electrical cables are not truly redundant. For instance, if two main engines in different engine rooms produce power that goes into a single cable that brings power to the propulsion motors, a problem to that electrical cable would cut off all propulsion power. Consider it like a highway: If an accident closes the road, traffic (i.e. electricity) won't move anywhere unless there is a detour or a second route that can provide another way around the accident.

Portside PowerWhen ships are docked and not moving, main engines and generators produce far more power than needed. In port, they are turned off, and smaller generators are used to supply the "hotel" load (i.e. lights, air-conditioning, the galleys, etc.). Actually, moving the ship through the water takes up the vast majority of a ship's need for power -- somewhere in the vicinity of 85 percent of the power a diesel electric plant produces goes to the propeller. The rest goes toward keeping the lights on and the passengers and crew comfortable.

This helps explain why hotel functions can sometimes be restored even if the ship's propulsion is not working -- separate generators provide power that does not go toward moving the ship. (However, if a fire knocks out the wiring that supplies the electricity, having a separate generator won't make any difference.)

Emergency GeneratorsSo what happens when things go wrong and the ship is dead in the water? All ships have an emergency generator to maintain vital electrical power.

These backup generators are always located higher up and outside the engine room spaces to insulate them from fire or damage to the engine room. Big ships require so much power that they might have two or more emergency generators. Even so, they will not have anywhere near the capacity of the main engines and generators. They don't produce enough electricity to move the ship, and they can't even supply all the limited power needed in port, mostly because of space constraints.

Thus, the emergency generator is instead used only for very essential navigation systems -- crucial bridge and communication equipment, a few critical pumps in the engine room (such as the pumps that supply fuel to the engines) and emergency lighting. (Cruise ship emergency lighting is generally pretty good. You can recognize which lights are operational on the emergency switchboard because there will be a little red dot next to the light. On your next cruise, take a look as you walk down the passageways and look for the red dots -- you might be surprised how many lights are powered in an emergency.)

Should the emergency generator also fail, ships are required to have -- and we're not making this up -- a battery backup. Battery rooms provide at least 24 hours of power to an even smaller list of emergency equipment. However, the essential systems they supply are so limited, they cannot power many hotel services and are certainly not enough to move the ship.

New Regulations and ImprovementsSo, what is being done to ensure incidents like the Carnival Triumph stranding don't happen again? Plenty, actually.

Until now, emergency power supplies have never been powerful enough to cover "non-essential" items, like air-conditioning, which is one of the biggest power draws of the hotel load. (That isn't likely to change in the foreseeable future. It may be uncomfortable to be hot and sticky on a ship, but it isn't unsafe.)

Nor have the vacuum pumps needed for the toilets been considered "emergency equipment" until this point. However, recent regulations entitled "Safe Return to Port" by the International Maritime Organization have come into effect for almost all passenger ships built after 2010. Recognizing that increasing passenger capacity makes it harder to evacuate large ships, these regulations are designed to ensure that in the case of a fire or other incident, there are enough redundancies so that passengers can stay safe longer -- and have basic services.

The newest ships that have launched (such as Royal Princess and Norwegian Breakaway) now feature full redundancies -- including two engine rooms and the doubling up of cables and electrical systems that snake throughout ships. This means that even if a fire destroys one main engine room and the generators that supply the power to move the ship, a separate engine room with enough power to propel the ship would still be operational. Although the ship would not be able to travel at normal speed, it would be able to navigate without the assistance of tugboats. Even more groundbreaking are the designations for providing basic services -- including specifications for one workable toilet for every 50 people.

There's something wrong with the ship that they can't fix between now and September????

We are on the ship July 22 but did not receive any email so far about any schedule changes. I don't think full costs has anything to do with it since barrels are below $50.

But strange they can predict a problem in three months but can't fix it?

No, it is not always bad service. I will say this as to your "EZ air" issue....that is an airline issue not Princess. They are no different then booking with a third party vendor. I leave Friday for LA and did not book EZ Air and both Delta and United changed my flight times and flight numbers without notification. Delta finally emailed 2 weeks after I discovered it and United's first change was sent an email 30 days later and have yet to receive an email about the latest change I found last week! United chose to cancel multiple flights leaving Vancouver leaving me no options and they could have cared less.

I used American Express Travel and they have notified me of flight time changes. Perhaps you need another TA.

 

The trend to only one choice per course does appear to be what we'll eventually receive with all specialty dining. It's interesting that the price went back to $25 after increasing to $29 last year. There's no doubt that we'll have plenty to eat & hopefully the menu will be well prepared.

I just booked Sabatini's for $29 each. The price did not go back to $25.