First-time Transatlantic-sunrise/sunset times

[chengkp75]

2 minutes ago, buchanan101 said:

Surely the period is the same, but in anti-phase, just like noise cancellation

The stabilizer will produce force in opposition, but it does so about 1/4 out of phase with the wave roll, so the sine curve gets a "bump" in it part way up or down the slope, which changes the roll period slightly.

 

4 minutes ago, buchanan101 said:

Works fine with a steady noise, or wave period, but if the wave period varied could be problematic - but I guess that can't really happen

Ocean wave period is never steady.

 

5 minutes ago, buchanan101 said:

QE, QV, QA only have two azipods don't they - do they also provide the steering?

Technically, all "azipods" provide propulsion and steering.  A "fixipod" is fixed straight ahead to only provide propulsion.  The two center pods on the Oasis class ships, and the center pod on RCI's Freedom class ships are "fixipods".  Apparently, having the two center pods only provide a straight fore/aft waterflow prevents the course control problems of QM2.  All ships with azipods experience the "azipod shimmy" to some extent (a port/stbd yawing motion aft) caused by the water flow coming into and leaving the propeller being swept back and forth as the pods make small corrections to keep course.  Having 4 large pods doing this, obviously caused large problems.

 

Many believe that cruise ships are "top heavy", but it is because the ships have so much "metacentric height" (so the center of gravity is actually lower than most think) that they are considered "stiff" vessels, with great stability.  However, as your research will show, a stiff vessel "snap" rolls, and this is uncomfortable, so the stabilizers were added to slow the roll period.

[Dranuc2016]

So... getting back to the OP question about length of daylight on a TA:

I have added the time between sunrise and sunset within parentheses.

 

Here is the information from a TA

Westbound TA in the summer 2019
Sunrise/Sunset as listed in the daily program

2019-08-11 sunrise 05:46 sunset 20:34 (14:48)
set clocks back 1 hour
2019-08-12 sunrise 05:03 sunset 20:08 (15:05)
set clocks back 1 hour
2019-08-13 sunrise 04:52 sunset 19:58 (15:06)
2019-08-14 sunrise 04:41 sunset 19:45 (15:04)
set clocks back 1 hour
2019-08-15 sunrise 05:35 sunset 20:26 (14:51)
2019-08-16 sunrise 06:28 sunset 21:03 (14:35)
set clocks back 1 hour
2019-08-17 sunrise 06:08 sunset 20:26 (14:18)
set clocks back 1 hour
2019-08-18 ? no daily program on disembarkation day

[steve4031]

I appreciate all of the information.  It was educational to find out that the ship can vary its course significantly and still stay on schedule.  

[buchanan101]

4 hours ago, steve4031 said:

I appreciate all of the information.  It was educational to find out that the ship can vary its course significantly and still stay on schedule.  

It can cross the Atlantic in as little as 4 or 5 days -  but max speed is a lot more expensive in fuel. I think the crossings used to be fewer nights (anyone? Was it 5?). It’s faster than cruise ships (max ~ 30 knots v QV ~ 24 knots)

[IB2]

8 hours ago, buchanan101 said:

It can cross the Atlantic in as little as 4 or 5 days -  but max speed is a lot more expensive in fuel. I think the crossings used to be fewer nights (anyone? Was it 5?). It’s faster than cruise ships (max ~ 30 knots v QV ~ 24 knots)

Yes, they could certainly do it in six days, possibly five at maximum speed - the slower pace is a mixture of economy (the diesel generators are cheaper to run than the aviation fuel turbines that push the speed up to maximum), contingency (so that they always arrive on time, regardless of weather or medical diversions), and marketing - they do seem to believe that crossings of a round-week maximise their appeal and income.

 

The old QE2 was originally scheduled to a five-day crossing, but dropped back to six days in the 1990s, I believe?

Edited December 9, 2022 by IB2
+

[chengkp75]

2 hours ago, IB2 said:

the diesel generators are cheaper to run than the aviation fuel turbines that push the speed up to maximum

While it is quite true that diesel fuel is cheaper than bunker fuel (that the diesel engines run on while on a crossing), the gas turbines on the QM2 do not run on aviation fuel, they run on MGO (Marine Gas Oil, or the equivalent of #2 heating oil (home heating diesel).

[Yaldi]

3 hours ago, IB2 said:

Yes, they could certainly do it in six days, possibly five at maximum speed - the slower pace is a mixture of economy (the diesel generators are cheaper to run than the aviation fuel turbines that push the speed up to maximum), contingency (so that they always arrive on time, regardless of weather or medical diversions), and marketing - they do seem to believe that crossings of a round-week maximise their appeal and income.

 

The old QE2 was originally scheduled to a five-day crossing, but dropped back to six days in the 1990s, I believe?

Yes, I made a five day crossing in 1993 on QE2 and by 1997 crossings increased to six days. My first Queen Mary 2 seven day crossing was in 2010 which became the normal trans Atlantic service the following year.
 

I suspect you are right that seven days is the sweet spot for maximising onboard revenue, appealing to the market and also a reasonable compromise by not thrashing the ship at constant higher speeds coupled with the related fuel economy. 

[TheOldBear]

The original [steam powered] QM and QE did five day crossings - but the turnaround between crossings was much longer than required for the QM2.

 

There is [somewhere on YouTube] a Cunard film describing the breakneck pace of a NYC turnaround for the QE - about 48 hours.

[Yaldi]

2 hours ago, TheOldBear said:

The original [steam powered] QM and QE did five day crossings - but the turnaround between crossings was much longer than required for the QM2.

 

There is [somewhere on YouTube] a Cunard film describing the breakneck pace of a NYC turnaround for the QE - about 48 hours.

I think the two ship trans Atlantic service was timetabled to sail on Wednesday, arrive on Sunday which ties in with the 48 hours turnaround. They carried mail, cargo, cars as well as passengers so longer turnaround times were probably needed to cope with it all including provisioning, bunkering and so on.

 

Thank you for the tip-off about the film, will have a look for it.

[exlondoner]

2 minutes ago, Yaldi said:

I think the two ship trans Atlantic service was timetabled to sail on Wednesday, arrive on Sunday which ties in with the 48 hours turnaround. They carried mail, cargo, cars as well as passengers so longer turnaround times were probably needed to cope with it all including provisioning, bunkering and so on.

 

Thank you for the tip-off about the film, will have a look for it.

Thursday departure from Soton.