Why cant the captain make up lost time

[Pellaz]

I've been on cruises where we've made up some -- or all -- of lost time, including one where we returned to Port Everglades from Grand Turk via the longer "southern route" (past Cuba) instead of the shorter route (up and over the Bahamas).

I think in the OP's case it was a pretty long distance between ports and they were already planning on taking it fast (as cruise ships go). People tend to forget that at maximum speed, cruise ships are still only clocking around 25-26 mph, max.

While it's fashionable to blame the corporation for cutting corners, I suspect there are other factors besides fuel costs at play, here.

[chengkp75]

The biggest reason they can't always make up time, especially coming south from NY and New England, is the Gulf Stream. At times it can be running at 6 knots northward, so a ship producing horsepower for 20 knots is only doing 14 over the ground. The Stream is seasonal on its intensity, as well as exactly where the center of track is, so sometimes in the year, you can make up some lost time due to reduced current, or steering a track that misses the center of the stream.

 

It can also depend on whether the ship has all engines available. The diesel engines get a full tear-down overhaul every 12,000 hours (about 2.5 years), and these overhauls take 3-4 weeks. So, many, many ships are steaming around out there without all the engines available. While the itineraries are set with the overhauls in mind, and the speeds capable without one engine, when time is lost, it can't be made up in these cases.

[CabinFeverInMI]

The biggest reason they can't always make up time, especially coming south from NY and New England, is the Gulf Stream. At times it can be running at 6 knots northward, so a ship producing horsepower for 20 knots is only doing 14 over the ground. The Stream is seasonal on its intensity, as well as exactly where the center of track is, so sometimes in the year, you can make up some lost time due to reduced current, or steering a track that misses the center of the stream.

 

 

 

It can also depend on whether the ship has all engines available. The diesel engines get a full tear-down overhaul every 12,000 hours (about 2.5 years), and these overhauls take 3-4 weeks. So, many, many ships are steaming around out there without all the engines available. While the itineraries are set with the overhauls in mind, and the speeds capable without one engine, when time is lost, it can't be made up in these cases.

 

 

 

I have heard that to fire up an extra engine it costs an extra 800 gallons of fuel per hour.

COST is the biggest reason captains have schedules, and want to stick closely to them.

 

 

 

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[BallFour4]

I have heard that to fire up an extra engine it costs an extra 800 gallons of fuel per hour. COST is the biggest reason captains have schedules, and want to stick closely to them.

There is no extra engine on a modern day cruise ship. Ships use fuel oil powered generator engines to produce electric power for two things, the small city afloat and the twin electric drive motors.

 

While not all the generators may be online at the same time there isn't the ability to increase speed by having all the generators running at the same time.

 

 

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[chengkp75]

I have heard that to fire up an extra engine it costs an extra 800 gallons of fuel per hour.

COST is the biggest reason captains have schedules, and want to stick closely to them.

 

 

 

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Yes, cost is the reason the itineraries are set as they are, but they do have the ability sometimes to make up lost time, and do so whenever they can.

 

A typical figure for diesel engine fuel consumption at optimum operating range (about 75% load) is 184 grams/hp-hr, and with engines on cruise ships running from around 10,000 - 24,000 hp, that equates to about 1.8 - 4.4 metric tons/hr or 480 - 1160 gal/hr (marine engineers don't think in terms of US gallons anymore). At today's prices that's about $500 - 1200/hr, but that is still only about 1/5 to 1/6 of the total fuel cost.

 

And, depending on where the ship is in its speed curve, and how much additional speed is required, it may be as simple as changing a small engine for a large one, which would not increase the fuel consumption as much as placing an additional engine on line. But I will say that the last few knots of speed requires a whole lot of power and a whole lot of fuel to get a marginal increase in speed.

Edited July 1, 2017 by chengkp75

[chengkp75]

There is no extra engine on a modern day cruise ship. Ships use fuel oil powered generator engines to produce electric power for two things, the small city afloat and the twin electric drive motors.

 

While not all the generators may be online at the same time there isn't the ability to increase speed by having all the generators running at the same time.

 

 

.

 

There are frequently "extra engines" on cruise ships. Most ships have between 4-6 diesel generators, and the power management software will optimize the configuration (some ships have two different sized engines) and number of engines to keep the load maximized on the engines running to meet the power demand, both for hotel and propulsion. When a ship is slow steaming between close ports, they will only run a couple of engines, and when they need full speed they will run all the engines. So, yes, they can increase speed by adding another engine online, up to having them all running which produces enough power to reach full design speed. If the itinerary between NYC and San Juan only called for some of the engines to make the required speed, then adding another generator would add speed, but this is not always possible.

 

And the beauty of diesel-electric propulsion is that all the engine/generator sets power a common power bus or "grid" just like all the power plants on shore, and this "grid" powers all the hotel and propulsion functions, so any generator can power the hotel, the propulsion, or both at the same time. There are no dedicated "hotel" generators or "propulsion" generators. All the power from however many generators are running is directed to whatever users require power, whether it is hotel functions or propulsion.

[ray98]

This is very conflicting. I don't know exactly why you came in late. But they can in-fact make up time. I was on the pride 2 years ago when we had to MediVac a passenger off. We left Baltimore got to mid South Carolina turned around toward North Carolina. Traveled north for about 2 hours and then sat there as the evacuation took place. Until we got back to where we turned around it was about 4 hours and 45 minutes of lost time. Yet still arrived at our first port only 1 hour and 30 minutes late. So somewhere we made up 3 hours and 15 minutes.

 

Not necessarily. Very few runs are spaced so that normal cruising speed is required 100% of the way to make it point to point on time. Most of the time the ship dramatically slows overnight or even comes to a standstill as they close in on the destination.

 

Your delay may have simply cut all of the buffer out of the trip.

[bUU]

Precisely. In some cases they can make up time and in other cases they cannot make up time.

 

This message may have been entered using voice recognition. Please excuse any typos.

[deborahjo]

There's also potential comfort to the cruisers/passengers.

 

We were going "full" according to what we were told to make up time from bad weather. Seas were still kind of rough. Sitting in MDR for dinner at rear of the Conquest. Vibration from engines and seas was so bad that multiple passengers including my DW left and fought over bathrooms to throw up in due to motion sickness. My DW never gets sea sick and has been on boats all her life. But that extra vibration made it unbearable and even I was queasy.

 

I'd rather miss an excursion and two hours in a port than deal with multiple complaints due to the level of comfort that had been brought down due to going faster than scheduled.

 

 

 

Agree [emoji817]%

 

 

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[LMaxwell]

Sailing south against the gulfstream it may be cost prohibitive to make up time, OR the currents and prevailing winds may have been higher than expected and they were trying to make up time and the best they could manage was 2 hours late leaving = 2 hours late arriving; it is possible that if they left on time you may have arrived 2 hours late. Those with experience with displacement hulls know that when you reach your efficiency point even adding an additional knot of speed can result in a 30%, 50%, or greater fuel consumption. An easy choice in an emergency, but not necessarily for a port of call.

 

I'd suspect a combination of those things above.

[JMAE]

We have been on the Pride 6 times every time while traveling south we traveled around 17 knots however traveling north we traveled 22 knots. This is due to the ship's schedule.

 

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[ray98]

We have been on the Pride 6 times every time while traveling south we traveled around 17 knots however traveling north we traveled 22 knots. This is due to the ship's schedule.

 

 

Not exactly....it very well may be the same standard cruising speed but the currents are doing exactly opposite things one each leg of the trip.

[sparks1093]

We have been on the Pride 6 times every time while traveling south we traveled around 17 knots however traveling north we traveled 22 knots. This is due to the ship's schedule.

 

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And the currents as previously mentioned. Coming north the ship is traveling with the current rather than against it.

[Purvis1231]

I am not an engineer or navigator but I do appreciate all those on the site that can explain all the important points of engineering and navigation. I have always been amazed that the cruise ships I have sailed were always on schedule.

[dan4182]

Um the real reason they cant speed up is.... Remember the last time they tried this. They lit the last boiler and hit an iceberg.. So no speeding up.

 

 

 

They even made some movies about that incident.

 

 

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[JMAE]

Top speed for cruise ship's systems to function properly is in the low 20 knot range.

 

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[Elaine5715]

Could buy it as simple saving money. If not for the number of times we have left port late. And arrived at the next on time.

 

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But the port agreements, pilot arrangements also cost money and coordinating with other ships trying to dock or access tenders. All that gets calculated vs fuel burn/costs.

[Trevor Fountain]

I take it you didn't ask the Captain if you could borrow a set of Oars and help him out then?