Chemtrails ?.. are you serious?

[matts-uk]

Yes! Even considering thousands of passengers, cruise ships are typically in the low teens for passenger mpg, possibly the worst form of mass transit.

Lies, damn lies and statistics. Efficiency and emission forecasts are like UK weather forecasts - Look long enough and hard enough and you are bound to find one you like

Passenger miles per gallon is a metric lacking a time quotient. As such, using PMPG to compare vehicles of vastly different speeds creates a fallacy by breaking the first law of thought.

The jet airline industry likes to talk about PMPG as it conveniently avoids the rate of consumption. The passengers on a jet aircraft reach their destination in a matter of hours and are then able to jump aboard another CO2 spewing air craft. The passengers on a ship however, will take days or weeks to travel the same distance and in the interim do not consume fuel further.

BTW I am not a treehugging zealot...More irritated by the fashion for obviously flawed analysis supporting a broken status-quo. Next we will have people claiming climate change can be reversed by selling and offsetting carbon credits, or shipping plastic waste 1000s of miles around the world.

Unfortunately the core of the global economy revolves around rewarding consumption. We (the planet's population) need to find a way to start to reverse that fact, to reward people for not consuming.

[Ttaskmaster]

As such, using PMPG to compare vehicles of vastly different speeds creates a fallacy by breaking the first law of thought.

Up there, you don't have time to think. If you think, you're dead.
But speaking of speed and jets...

[Zak33]

The passengers on a jet aircraft reach their destination in a matter of hours and are then able to jump aboard another CO2 spewing air craft. The passengers on a ship however, will take days or weeks to travel the same distance and in the interim do not consume fuel further.

good thought but it doesnt change the actual efficiency. A distance covered by a certain amount of people using a certain amount of fuel. If all the people landed and sat still and did nothing for 2 weeks while the cruise ship got over the ocean, the numbers would stack
in your theory.
And efficiency HAS to take time into account. It has too.
If I am offered a car that does 100 mpg but getting home takes 5 hours, where my normal car does 50mpg but I am home in 90 minutes, guess which is more effective for my life? If it's just about CO2 then we might as well all walk everywhere. Better still, not go anywhere.

[Zak33]

good thought but it doesnt change the actual efficiency. A distance covered by a certain amount of people using a certain amount of fuel. If all the people landed and sat still and did nothing for 2 weeks while the cruise ship got over the ocean, the numbers would stack
in your theory.
And efficiency HAS to take time into account. It has too.
If I am offered a car that does 100 mpg but getting home takes 5 hours, where my normal car does 50mpg but I am home in 90 minutes, guess which is more effective for my life? If it's just about CO2 then we might as well all walk everywhere. Better still, not go anywhere.

properly good reply

[matts-uk]

Up there, you don't have time to think. If you think, you're dead.

That's just the airlines leaning off the Oxygen to save a buck.

But speaking of speed and jets...

Independance Day Resurgance,
Point Break 2015
Blues Brothers 2000
Starship Troopers 2
T2 Trainspotting
Top Gun 2020 ?

[Ttaskmaster]

That's just the airlines leaning off the Oxygen to save a buck.

No, it's a quote from the film...

Independance Day Resurgance, etc

What are you getting at?

[watercooled]

Lies, damn lies and statistics. Efficiency and emission forecasts are like UK weather forecasts - Look long enough and hard enough and you are bound to find one you like

Passenger miles per gallon is a metric lacking a time quotient. As such, using PMPG to compare vehicles of vastly different speeds creates a fallacy by breaking the first law of thought.

The jet airline industry likes to talk about PMPG as it conveniently avoids the rate of consumption.

I think you could be guilty of the very thing you complained about in your first line!

It actually goes further than Zak33's example. Rather than getting somewhere slower but more efficiently, you're trying to argue that getting somewhere more slowly and LESS efficiently is logical. It is not. Well not unless you plan to spend a given amount of time travelling rather than a set distance which is something of a bizarre choice unless you're just doing it for the enjoyment of travelling itself!!

It's the power vs energy thing - something using more power does not make it less efficient if it uses less energy overall by completing the job more quickly!

[kalniel]

properly good reply

Is that you, Angus?

[ik9000]

Is that you, Angus?

I'd missed that.

Taylor, who was previously the minister for cybersecurity, has since deleted the self-congratulatory comment.

uh-oh. A minister for cybersecurity hasn't mastered social media? Next they'll be telling me the minister for education has never taught in a school, or the minister for health isn't medically trained, and the defence minister has never been involved in even the volunteer reserves, nevermind the regular forces.

[Xlucine]

... and the defence minister has never been involved in even the volunteer reserves, nevermind the regular forces.

Penny Mordaunt is in the RNR:
https://www.royalnavy.mod.uk/news-an...nr-on-the-dart

[matts-uk]

I think you could be guilty of the very thing you complained about in your first line!

The first two lines in my previous post allude to the validity of the comparison. I am arguing that ships and aircraft are different enough that comparison of the respective PMPGs is illogical. The logical test is to change the terms of the equation. Within a logical comparison the most efficient will remain the most efficient. However, changing the unit of measure to Tons per Mile Per Gallon results in ships beating aircraft by a country mile. PMPG and TMPG are similar measures of efficiency. The most efficient being simultaneously the least efficient is an illogical conclusion, hence the comparison is illogical.

It actually goes further than Zak33's example. Rather than getting somewhere slower but more efficiently, you're trying to argue that getting somewhere more slowly and LESS efficiently is logical. It is not.

Zak had to redefine reality to make his point. The truth of the matter is the passengers and the jet airliners they travel on do not stop. The passengers continue to consume, while the aircraft turns around and enables another load of passengers to consume fuel quickly and efficiently.

Rather than getting somewhere slower but more efficiently, you're trying to argue that getting somewhere more slowly and LESS efficiently is logical. It is not.

I am not arguing that at all. The choice I presented is between jet aircraft and ships. The jet is fast and efficient, the ship is slower and less efficient. Slower and more efficient was not an option - The jet would fall out of the sky(!)

This is what I said...

" The passengers on a jet aircraft reach their destination in a matter of hours and are then able to jump aboard another CO2 spewing air craft. The passengers on a ship however, will take days or weeks to travel the same distance and in the interim do not consume fuel further. "

The proposition is the slower speed of the ship limits the overall rate of consumption by the passengers while the much faster aircraft increases it.

It's the power vs energy thing - something using more power does not make it less efficient if it uses less energy overall by completing the job more quickly!

Efficiency is the ratio of output to input, expressed as a percentage. The classic physics (thermodynamic) definition of efficiency is energy output divided by energy input. Work efficiency is defined as units of work divided by time spent. Energy is 'lost' to inefficiency in the process of doing work. Thermodynamic efficiency reduces the loss but: i) Energy must be expended to realise the potential saving. ii) The saving is a fraction of the energy expended. Increasing work efficiency merely speeds up the rate energy is expended. Within these simple definitions there is no accounting for fuel nor emissions nor the necessity of the work being done.

Within the sustainability proposition both fuel and the capacity of the Earth's atmosphere to tollerate emissions are limited. A simple analogy that may be easier to digest. You are paid £70 a week on Friday and need to spend £10 on a meal deal each day to survive. Greg's runs an offer of a 10% discount (energy efficiency) when you buy 2 meals at the same time (work efficiency). The offer is more efficient but you must spend £18 per day to realise the potential saving. Taking advantage of the efficiency 'savings' causes you to starve to death around Thursday.

[matts-uk]

No, it's a quote from the film...

Airlines lean off the Oxygen to save money. Take it too far and it becomes difficult to think, followed by death from asphyxiation. My apologies for the attempt at geeky irony.

What are you getting at?

The raft of Hollywood do-overs have been underwhelming IMO.

[watercooled]

The first two lines in my previous post allude to the validity of the comparison. I am arguing that ships and aircraft are different enough that comparison of the respective PMPGs is illogical. The logical test is to change the terms of the equation. Within a logical comparison the most efficient will remain the most efficient. However, changing the unit of measure to Tons per Mile Per Gallon results in ships beating aircraft by a country mile. PMPG and TMPG are similar measures of efficiency. The most efficient being simultaneously the least efficient is an illogical conclusion, hence the comparison is illogical.

TMPG is totally irrelevant when your objective is to move people. It might as well be MPG per number of letters painted on the side.

Zak had to redefine reality to make his point. The truth of the matter is the passengers and the jet airliners they travel on do not stop. The passengers continue to consume, while the aircraft turns around and enables another load of passengers to consume fuel quickly and efficiently.

I think you might be the one redefining reality TBH. Why would a passenger going on holiday or a standard business trip not stop when they get to their destination? You're implying the amount of people travelling so frequently they're basically bound by travel speed make up something of a majority, or possibly all passengers depending how you interpret your post? The fact the vehicle continues to consume fuel after a journey is irrelevant, a plane uses less fuel to move the same amount of people a given distance than a ship - a ship may take one journey to move a given amount of people whereas a plane (or a fleet of them) may need to make 50 journeys to move that same amount of people, but still uses less fuel in the process. For passenger ships, a more substantial portion of energy goes into moving the vehicle itself when compared with a plane.

A more sensible approach would be to not take overseas holidays one after the other, or to use the Internet to do business rather than flying everywhere, where possible, rather than deliberately travelling less efficiently as a way to limit the amount of journeys.

Cargo may be a different story, but we're talking about passenger travel here.

I am not arguing that at all. The choice I presented is between jet aircraft and ships. The jet is fast and efficient, the ship is slower and less efficient. Slower and more efficient was not an option - The jet would fall out of the sky(!)

This is what I said...

" The passengers on a jet aircraft reach their destination in a matter of hours and are then able to jump aboard another CO2 spewing air craft. The passengers on a ship however, will take days or weeks to travel the same distance and in the interim do not consume fuel further. "

The proposition is the slower speed of the ship limits the overall rate of consumption by the passengers while the much faster aircraft increases it.

Which is an obvious statement but a rather pointless argument to make in today's world.

Efficiency is the ratio...

We're talking specifically about the efficiency of moving passengers. A ship is less efficient at doing that.

Within the sustainability proposition both fuel and the capacity of the Earth's atmosphere to tollerate emissions are limited. A simple analogy that may be easier to digest. You are paid £70 a week on Friday and need to spend £10 on a meal deal each day to survive. Greg's runs an offer of a 10% discount (energy efficiency) when you buy 2 meals at the same time (work efficiency). The offer is more efficient but you must spend £18 per day to realise the potential saving. Taking advantage of the efficiency 'savings' causes you to starve to death around Thursday.

We don't need a simple analogy, it's quite clear what you're saying, it's just illogical. To honour the analogy, freeze the second meal for the next day, or take turns to pay with a friend. The analogy suggests taking extra passengers on board the aircraft just for the sake of it; wastefully, in order to balance the efficiency for no particular reason.

[Ttaskmaster]

Airlines lean off the Oxygen to save money. Take it too far and it becomes difficult to think, followed by death from asphyxiation. My apologies for the attempt at geeky irony.

The quote was about having no time to think, not the inability to think.
Geeky irony fail due to not getting the geek reference, I'm afraid.

The raft of Hollywood do-overs have been underwhelming IMO.

This isn't a do-over, remake or reboot. It's presented as a direct and intentional sequel.
Also, unlike the above-mentioned do-overs, this has been in the works for many years but was badly hit when director Tony Scott died in 2012.

whereas a plane (or a fleet of them) may need to make 50 journeys to move that same amount of people, but still uses less fuel in the process.

We seem to have begun this based on "Efficiency and emission forecasts"... I hear lots of talk about TPMPGPMG and other letters, which is good for volume over distance against fuel units used... but you need to factor in type of fuel and pollution produced per unit.

[watercooled]

True. I know some comparisons are made to a sort of 'equivalent' MPG, based around emissions. I'm not sure if that would apply to the units quoted here. However I imagine it would only put more distance between ships and aircraft given the heavier fuel in use for ships?

[DanceswithUnix]

So am I getting this right, 5 up in my petrol car doing 40mpg gets me 200 PMPG? Interesting way to think of things, must have a use somewhere. Maybe.