One Giant Cargo Ship Pollutes As Much As 50M Cars

thecarchik writes "One giant container ship pollutes the air as much as 50 million cars. Which means that just 15 of the huge ships emit as much as today's entire global 'car park' of roughly 750 million vehicles. Among the bad stuff: sulfur, soot, and other particulate matter that embeds itself in human lungs to cause a variety of cardiopulmonary illnesses. Since the mid-1970s, developed countries have imposed increasingly stringent regulations on auto emissions. In three decades, precise electronic engine controls, new high-pressure injectors, and sophisticated catalytic converters have cut emissions of nitrous oxides, carbon dioxides, and hydrocarbons by more than 98 percent. New regulations will further reduce these already minute limits. But ships today are where cars were in 1965: utterly uncontrolled, free to emit whatever they like." According to Wikipedia, 57 giant container ships (rated from 9,200 to 15,200 twenty-foot equivalent units) are plying the world's oceans.

Comments

One can dream...

[grub]

Screw the people that frown on those who drive Hummers.

I want to be rich enough to say "I'm taking the family on a cruise across the ocean on our personal cargo ship." The captain would floor it from the dock and leave a 30 km long black trail of smoke.

Re:One can dream...

[Rei]

This whole thing is so distorted. The REASON that we don't mandate these ships use strong pollution controls or clean fuels is specifically because pollution is part quantity, part location. If there's nobody to breathe a pollutant before it degrades, it's not hurting anyone. Car exhaust is released at ground level in populated areas.

In terms of fuel consumed and CO2 released, ship pollution from transporting a car (and all of its component parts) is a small fraction of the fuel consumed and CO2 released in the vehicle's lifespan. Cargo ships are the most efficient way, from a fuel and CO2 perspective, to move a given mass of freight (even more than trains), at nearly 500 miles per gallon per ton. You can haul your average car from Tokyo to LA using under 20 gallons of fuel. Now, there's going to be all sorts of soot and sulfur released from that fuel because the regulations are so lax -- but who's it going to hurt in the middle of the Pacific's vast nutrient-devoid dead zones? You're probably doing more to fertilize them than hurt them.

The actual pollution problems, BTW, are when the ships show up in port. The "last leg" of travel causes the vast majority of their health consequences, and there's a lot of work underway to clean it up.

Re:One can dream...

[AkkarAnadyr]

The majority of open ocean is a nutrient-poor environment even for algae and plankton.

It is a less productive desert than just about anywhere else on Earth.

What 'nutrient-rich zones that died off' am I missing?

Re:One can dream...

[AaronW]

When my father was in the US Navy in the 1963 the aircraft carrier he was on, the USS Ranger, had a drag-race with the USS Kitty Hawk. It made the cover of hot rod magazine. The USS Ranger won. I'd call this flooring it.

Apparently the captain asked the admiral if it was OK. He said no so the captain told him to go back to sleep and did it anyway.

Re:One can dream...

[Rei]

Chlorophyll map of the world's oceans.

Now pay close attention to the scale at the bottom. Even the stuff in green has 1/20th the photosynthetic activity as the stuff in red. Note how tiny of an area is in red.

Most of the world's oceans are *extremely* poor in life. The limiting factor for photosynthesis in most of the world's oceans is not light or CO2, but iron. Iron sinks in aggregate and is poorly soluble.

Re:One can dream...

[DZign]

Since a few years ships are already required to switch to low-sulfor fuel when they come near the coast or enter ports..

Several types of marine fuel exist: MGO, MDO, HFO,..
HFO (heavy fuel oil) is getting banned in some parts of the world.
And yes this means vessels actually have 2 or 3 different types of fuel on board and switch over from one type to another.

The economic crash of 2 years ago was beneficiary for the environment btw.
The years before it, prices for renting a ship (baltic dry index) was so high that only the rent made up the largest part of the cost, fuel costs were low in comparison. So cargo vessels were instructed to go full speed (and consume/pollute more).
Now the BDI dropped, the rent is lower and it's again a matter of optimising days at sea / consumption (slower speed = less consumption, so renting a vessel 1 or 2 days longer can be better because fuel savings are more than the extra rent you pay for these days).

A lot of old (and more polluting) vessels also were laid in docks or are scrapped the past 2 years as there suddenly wasn't enough cargo to transport..

disclaimer: I work at the it department of a group of companies that operates cargo vessels.. have worked on a program to register their trips and optimize fuel costs/speed/...

Re:One can dream...

[dylan_-]

Nope, he was pretty close. Your figure is way out - there's no way a gallon of fuel put into a cargo ship would move 1 ton 500 miles (or the inverse)....Fuel consumption is listed as 3.80 litres per second, or 1 gallon per second (3600 gallons/hour). That's a hell of a lot of fuel, and far off your 1 gallon = 1 ton moved 500 miles.

So, 3600 gallons/hour. The engine you mentioned is on the Emma Mærsk. Say it cruises at about 20 mph (speed is given as 29, but let's be conservative). That's 180 gallons/mile.

Now, to get 500 ton-miles/gallon you need to be carrying 500*180 = 90,000 tons. The Emma Mærsk can actually carry 154,000 tons. That works out at 856 ton-miles/gallon.

So, he may have been wrong, but in the opposite direction to the one you thought. Cargo ships do use an insane amount of fuel, but they also carry an insane amount of cargo.

Could be a problem

[BadAnalogyGuy]

We should get rid of these ships.

Let us DRIVE our containers across the ocean!

Re:Could be a problem

[MBGMorden]

Let us DRIVE our containers across the ocean!

While that likely wouldn't work, you do realize that for thousands of years we moved items by sea all across the globe via a completely free and environmentally method of propulsion: the sail.

Re:Could be a problem

[MBGMorden]

Sailing ships don't require that: WOODEN ships do. Though ships of old were typically wooden, there is no requirement at all that a sailing vessel be made of wood (and modern sailing vessels typically aren't).

Don't confuse the proposal that we use sails more as a proposal that we go back to using Spanish Galeon's. You can merge the concept with a more modern approach as needed.

Re:Could be a problem

[Yvan256]

Because, of course, using sails as a propulsion method requires a ship made of wood...

Re:Could be a problem

[MBGMorden]

Point taken, but consider the following:

1. If the technology had continued to be developed, I'm sure we would have seen larger, faster, and more sophisticated sailing vessels used for shipping, likely resulting in far greater efficiencies today even with sailing compared to then.

2. When you consider the utter mess we're making of this planet, reduced shipping capacity isn't that bad of a thing to accept. It's akin to finally realizing that though racking up credit card debt can net you a lot of goodies, eventually you have to stop. That may mean a reduction in life style, but it's something you have to accept eventually. As it is now, there's no damn reason why the spoons and forks in your local stores should need to be shipped from halfway across the friggen planet. Manufacture some of the small trivialities closer to home. Make sure that the stuff we're shipping across the oceans have a legitimate NEED to travel that distance. Artwork? Family heirloom? Passengers? Sure, send those over. The knick-knacks at the dollar store though? I don't have much sympathy if that particular valve is shut off.

Re:Could be a problem

[DesScorp]

Actually sailing ships required the destruction of vast forests (one of the reasons Britain wanted North American colonies was for the wood to build ships with). They generally didn't last that long and had to be replaced frequently. So their effect on the environment wasn't minimal.

Bullshit. Ships didn't require THAT much wood, and Britain didn't want North America simply to build wooden ships. They wanted North America because things like you know, houses are still made of wood. But more importantly, they wanted America for its other resources, including sheer space for colonization.

  As for the ships not lasting all that long... by what standard? A typical non-aircraft carrier, steel-constructed US Navy vessel has a service life of around 30 years. Wooden commerce and naval vessels from the 1600's onwards had service lives of about.... 30 years. Navies went to steel because they made better warships, not because of any scarcity of wood. Nelson's favorite warship, HMS Agamemnon, was in service 28 years and was still one of the prime warships of the Royal Navy when she was wrecked in bad weather in 1809. It wasn't uncommon for navies to put a ship in the yards after 15 years, cut her in half, and literally splice in a section to maker her bigger, then return her to service as a larger vessel for another 15 years or so.

Re:Could be a problem

[Shadow Wrought]

Though ships of old were typically wooden, there is no requirement at all that a sailing vessel be made of wood (and modern sailing vessels typically aren't).

We know that the only things that float are wood, ducks, witches, and the occasional very small pebble. If not wood than what, ducks? A duck can't even carry a coconut without sinking. Small pebble can't carry very much, and witches are incredibely difficult to work with. So tehre you have it: wood. So sayeth the Ways of Science.

Re:Could be a problem

[spun]

Small nitpick, wooden shipbuilding techniques before ~1800 required long pieces of wood for the strakes, and specifically curved pieces of wood for the scantlings. Shorter pieces worked too much at sea, making the ships hog and sag, and creating leaks. A typical third rate 72 gun ship of the line required over 5,000 old growth oak trees to build. Finally, thirty years was the service life discounting rebuilds, which could extend the life of a ship to double that, or more.

I have heard the theory that Britain wanted American wood for ships in other places before this. We have a type of oak, White Oak, that is particularly suited to shipbuilding due to its strength and resistance to splintering.

Re:Could be a problem

[c0lo]

That may mean a reduction in life style, but it's something you have to accept eventually.

(hmmm... you seems so willing to sacrifice my lifestyle... what about yours?)
Then

The knick-knacks at the dollar store though? I don't have much sympathy if that particular valve is shut off.

Better still... download them over the Internet.

Of course I'm kidding ... actually going on a tangent (what would /. be good for, other than switching the thoughts from useful work, so why not continue?)... anyway, that's a major difference between IT and industries producing tangible goods: while for the later one can quantify the impact on environment of off-shoring/outsourcing practices, in IT the impact is too small to count.

Now that the context is set, here comes the question: would you be willing to sacrifice your life-style (not mine) in the conditions your everyday knick-knacks costs you 3-4 times over, while living under the constant risk of having your job outsourced?
(and, if you are not working in IT, why do you feel entitled to recommend solutions that "should be good for all"?)

Re:Could be a problem

[AkkarAnadyr]

It's a simple question of weight ratios. A five-ounce swallow cannot carry a one-pound coconut.

You need two swallows, with a strand of creeper held under the dorsal guiding feathers.

Re:Could be a problem

[garyebickford]

I worked as a tree thinner a long time ago. Our job was to go into an area (in the national forest) and thin the little baby trees down to about one every 10 feet. Then the ones that were left would grow faster, straight and tall - and since we preferentially removed less valuable species, the ones that remained tended to be the more valuable ones. I figured out that I was killing about 12000 baby trees per day (over about 10 acres). The ones that were left would be about 430 per acre, so ten acres would provide about 4300 trees. So it's not a very big forest in pure acreage. The time it takes to GROW the trees is significant, of course. There's a long time between a four-foot sapling and a mighty Douglas Fir - especially for the big diameter trees where you get more of the 'clear' knot-free wood.

Old boat builders (and some present-day boat builders) look especially for certain parts of trees. For example, the curved sections where the tree spreads out its roots tend to be very good for 'knees', taking advantage of both the curved grain and the extra density and strength that the trees develop in that area.

Re:Could be a problem

[Nadaka]

That is why the top 50 cargo ships should be nuclear powered. Clean, efficient, fast, consistent.

Re:Could be a problem

[Nefarious Wheel]

The most energy efficient ground transport, I've been told, is a horse riding a bicycle.

Re:Could be a problem

[shutdown -p now]

That is why the top 50 cargo ships should be nuclear powered. Clean, efficient, fast, consistent.

We've had some experience with the use of nuclear propulsion for civilian ships, and specifically for merchant ships. However, the history seems to show that its not economically viable, or at least borderline so, since only one is still going.

It did work very well for Soviet ice breakers, though.

Which is worse?

[decipher_saint]

One big ship or lots of smaller ships? Is it time to lose "the fear" and go nuclear on cargo vessels?

Re:Which is worse?

[RsG]

I suspect the resistance to using a nuclear cargo vessel has less to do with anti-nuclear fears and more to do with the cost of operating them.

This has come up before, and I'll say it again for good measure: naval nuclear reactors are expensive. If they weren't, you can be sure the military would use them on cruisers and destroyers. As it stands the only vessels that use a nuke plant are carriers and subs, both expensive as hell, and the latter only use nuke plants because they don't need to surface for oxygen (on a pure operating cost basis diesel-electric subs win out).

Plans for nuclear surface ships below carrier weight have been put forward, and axed repeatedly, almost always on the basis of cost alone. And if the American navy says something is too expensive, believe me, it's too expensive.

Now, what I wonder is, would a cargo vessel be less polluting if it used a multi-hull design to reduce drag and was fitted with more advanced filtration system to mitigate the worst of its exhaust? That's a lot more achievable than the nuclear option, and wouldn't sacrifice cargo capacity, unlike the sail option put forward earlier in the thread.

Re:Which is worse?

[cobrausn]

All the current Navy subs and ships that use nuclear reactors use reactors designed in the 60s / 70s. The decomissioned cruisers were expensive because of the cost of keeping enough trained personnel (like myself) on hand was much higher when you have to sustain those people out at sea; something like 50% of the staff of a nuclear cruiser was engine room staff.

We live in a new era as far as this technology is concerned - new designs are mostly automated and very efficient. We need to take this step forward, not just at sea but on land as well. Nuclear power is the best answer we have for large-scale power generation that could keep us moving forward until we discover a better energy source.

Or until world war breaks out and we all die. North Korea, South Korea... I'm looking at you.

Re:Which is worse?

[RsG]

Well, I agree with you that we need to take the nuclear option much more seriously, for power generation purposes. Something needs to replace all those coal fired power plants, and we're still a ways off from being able to build commercial fusion reactors.

However, I'm a realist. I can't imaging nuclear power ever winning points on cost. And the reason for this is not just that the current crop of 40 year old+ reactors is expensive to operate.

If you want to make any piece of technology virtually failure safe, you can do so. You can make a building that will survive every earthquake. Or a computer that cannot crash. Or (insert-imaginary-perfect-machine-here).

What you can't do is make such technology cheap. Systematic redundancy, backups upon backups, religious levels of maintenance, every piece of equipment built to specifications that vastly exceed the operational reality - all of these are possible, and they all cost a fortune.

There are only a couple of areas of human engineering where we build with such precise paranoia around failure. Nuclear power is one of them. And the reason for doing this with nuclear power is that we're properly paranoid about it, because failure carries with it such consequences. An excellent study in this is to contrast Three Mile Island (where the safeties were well designed) with Chernobyl (not so much).

Nuclear power done right is going to be expense. We can cut more corners with anything else. Now, this doesn't mean we shouldn't use nuclear power, but it does mean that the best use for it is in large commercial power plants.

Another Slashverisement for HighGear Media?

[spun]

First off, this article appears ripped straight from the UK Guardian. Secondly, what's with all the promotion of HighGear Media sites recently? Slashdot is not your megaphone, guys, lay off.

Re:Another Slashverisement for HighGear Media?

[cappp]

Also, it's a story from 9th April 2009 which was then covered on 15th April on said site. The original Guardian piece can be >found here. Hell Reuters posted an article in responce on 20 November 2009 where they added an interesting point

Shipping is slowing climate change by spewing out sunlight-dimming pollution but a clean-up needed to safeguard human health will stoke global warming, experts said Friday. "So far shipping has caused a cooling effect that has slowed down global warming," Jan Fuglestvedt, of the Center for International Climate and Environmental Research Oslo (CICERO), told Reuters....Toxic sulphur dioxide emitted by burning bunker fuel accounted for the deaths of an estimated 60,000 people worldwide in 2001 through cancer and heart and lung disease, according to a previous study. A clean-up would save thousands of lives. But sulphur pollution from the fast-growing shipping industry also helps create clouds by providing tiny seeds around which droplets form. Clouds have a cooling effect since sunlight bounces off their white tops.

What are they going to do about it?

[guruevi]

Most of those ships are not registered in the US or Europe or any 1st world country. They are registered in Panama, Aruba or wherever there are no taxes and no regulations. And you can't really stop them coming into your harbors without affecting the local or even global economy.

On the other hand, how much pollution would it generate to bring those products in on more smaller ships or on trucks through a series of tubes in the ocean.

Re:What are they going to do about it?

[Omnifarious]

Impose tariffs based on what kind of cargo ship the stuff came in on. That's what they can do about it.

Re:They're in the middle of the ocean.

[LWATCDR]

You actually have that correct.
This really is a bunch of bad science.
No discussion of VOCs or CO2 just particulate and SOX emissions.
Well particulates at see are probably going to be pretty harmless. They will fall into the sea.
SOX may or may not be an issue but motor vehicles really don't emit hardly any sulfur. I wonder what percentage total world emissions of sulfur this is.
At least in the US ships shift to cleaner fuel when in coastal waters. Yes reducing the sulfur is also a good idea but this is really a worst case the sky is falling story.

Stop Buying Crap!

[lazarus]

Honestly, how much of our current problems would go away if we just stopped buying the cheapest crap we can find? Trade imbalances? Global pollution? Landfill? We really have to get away from the whole "I want it right now, and I want it cheap, and I don't care how crappy it is if it just makes me happy for a few minutes." Here is an idea: Do some research. Buy a quality product that will last you the rest of your life instead of one you have to throw away next week. And if you can't afford it right now? Save up until you have the money for it. Trust me. You'll appreciate it more.

Re:Stop Buying Crap!

[AnonymousClown]

. Buy a quality product that will last you the rest of your life ...

Easier said than done. Aside from things that are designed not to last, things wear out - regardless of their quality.

Also, how can you really tell? Consumer Reports doesn't do studies on how long things last on most of their reviews and even then, it's only for the first few years, like with appliances. And the "you get what you pay for" line is not true.

I just consume less overall.

Re:Stop Buying Crap!

[Trogre]

Ah, but check the back. It was DESIGNED by Apple in sunny California, so everything's just fine!

Not the same as carbon emissions

[EnglishTim]

It doesn't really tell the whole story. The way the story's worded, you'd think that car emissions are a drop in the ocean (ha ha ha) compared to cargo ship emissions, but that's only true for a certain range of pollutants, and it's certainly not remotely true for carbon emissions.

Re:Not the same as carbon emissions

[PPalmgren]

Those are the heavy particles like sulfur emissions, which are controlled close to the coast. The ships switch fuel when they are like 50 miles from a port. I think the logic is that these heavy emissions actually sink into the ocean in international waters at diffuse levels not harmful enough to do damage (also that it would significantly increase the cost of all overseas goods).

Something of note is that those ships are the single most efficient way to move massive amounts of cargo in the world. I can't find the graph, but there's one online somewhere that shows the difference between flight, car, rail, and ship efficiency, and it looks like an exponential growth curve.

One thing about the industry is that fuel costs are the single highest expense (even over the $100m/piece containerships), so it is in their best interest to be as efficient as possible. The most efficient container line has the lowest cost, and thus the highest profit or lowest rates. As long as regulations are in place to protect people from known harmful practices (like the fuel change in national waters), I don't think any more is necessary.

Misleading statistics

[Saishuuheiki]

Saying that one ship pollutes as much as 50million cars is misleading. To be completely accurate, you must say one ship produces as much sulfer-pollution as 50million cars.

Now I have no doubt that this is still quite bad, but this doesn't mean that it has 50million times as much carbon emissions as cars. A quick google search shows that this can cause breathing problems and acid rain (both very bad) it doesn't seem to be a global warming problem. When you blindly say it pollutes 50million times as much of something cars now pollute very little of, it makes good headlines but it's bad science.

Re:Misleading statistics

[RobVB]

Exactly. The "50 million times more" thing is about sulfur oxides emissions, and honestly this number doesn't seem extraordinary to me. Diesel oil and gasoline have virtually no sulfur in them, while the Heavy Fuel Oil (HFO) that powers most ships is about 2% sulfur.

HFO is what's left when all the "good stuff" is extracted from crude oil. This "good stuff" is mostly shorter hydrocarbons such as methane, ethane, propane and butane (gases with 1 to 4 carbon atoms in them), gasoline (roughly 5 to 7 carbon atoms) and diesel oil (8 to maximum 21 carbon atoms).

What's left is an incredibly dirty, viscous, and nearly useless goo (asphalt is one other use, there aren't a whole lot). It still has a high energy density which makes it a decent fuel, but it's so viscous (because it consists mostly of very long hydrocarbon molecules) that you have to heat it up to around 80 degrees centigrade (176F) to even pump it into an engine. It also has high amounts of pollutants, because all the "clean" stuff has been taken out and you're left with all the dirty stuff. It is technically possible to remove most of the sulfur from this goo, but that means refineries would end up with giant piles of sulfur that nobody wants, and they'd have to dispose of it somehow. That's a cost refineries aren't willing to pay, so they just leave it all in to be burned up.

Legislation is being made to reduce HFO use in some heavy traffic areas (such as the North Sea in Europe), forcing ships to switch to clean diesel fuel in those areas. Of course, shipowners are against this because diesel is about 3 times as expensive as HFO. If all the ships in the busiest sea in the world suddenly start burning diesel fuel, you can expect the price to go up for everyone. Which is why we keep on burning the bad stuff.

Location Matters

[pavon]

If they completely relaxed emissions rules for cars then regardless of whether world-wide pollution decreased we would have smog in all the major cities, just like before emissions controls were put into place. Different types of pollution have different area ranges where their effects are felt, and our laws need to take this into consideration.

economics

[confused one]

It's a question of economics. They're built to operate as cheaply as possible. That includes fuel efficiency. So, I'd expect the engines to operate fairly efficiently, in order to minimize the fuel cost; however, that does not mean they minimize pollution. In addition, these ships often use the cheaper heavy fuels, like No. 6 fuel oil, which tend to be higher in sulfur and other contaminants. Until it's cheaper to operate the ship on something else, this will not change.

"Going Nuclear" on cargo vessels

[DesScorp]

One big ship or lots of smaller ships? Is it time to lose "the fear" and go nuclear on cargo vessels?

Fear has nothing to do with it. Expense does. We've built nuclear merchant vessels before. They're just too expensive to operate. We built a fast, beautiful nuclear merchant ship (the NS Savannah) as a technology demonstrator, and when companies looked at the costs involved, they simply didn't see the point. Only a handful of nuke cargo ships were ever built, and only the Russians used them for any length of time.

Re:Concentration

[jpmorgan]

But that's exactly the point I'm making. Emission standards for cars aren't based on the 'sulfur emissions in Montana impacting a farmer in Wyoming' basis, they're set on 'sulfur emissions in New York impacting someone in New York.' By the time particulates from a ship in the middle of the pacific have diffused their way to population centers, they're insignificant. Otherwise LA's infamous smog clouds would cover the entire western seaboard.

Imposing the same standards on container ships doesn't make sense, since the standards are there to solve a problem that container ships don't have.

Re:Proportions seem to be missed

[RobVB]

I'll quote some math I did about a year ago in this post.

While the amounts of HFO burned by, say, the Emma Maersk are enormous (about 300 metric tonnes per day at full operation), this is almost nothing when compared to trucks. Assuming 300mt/day at a cruise speed of 25 knots (over 45km/h), that equates to roughly 30 tonnes per 100 km. A semi-trailer truck pulling two TEU containers runs at around 30 liter per 100 km (that's around 8 mpg). This means the Emma Maersk, carrying 14000 TEU, uses 1000 times as much fuel as a truck carrying 2 TEU, which makes this ship about 7 times as fuel efficient as trucks.

Already exists

[RobVB]

This has been developed and put into use by a German company: SkySails. They report fuel savings of up to 30% in some conditions.

And yes, cutting speeds by about 10% reduces fuel use for the same distance by about 20%. This happens all the time in economy dips. Since fuel is the largest cost in shipping and its share in total costs keeps rising, it's an easy way to save a lot of money by offering up a little time. Maersk, the big container line, has reduced the operating speed on its ships from 22 to 20 knots because of the global economic recession. This is a pretty hard thing to do for them, because their ships operate on a schedule and have to stick to it, so changing operating speed means changing the schedule worldwide.

In other types of shipping such as bulk carriers and tankers, this practice is much more common. When there is little demand, ships can go slower to save money so they make more profit per job. When the economy is doing well and demand is high, shipping prices can suddenly skyrocket. In this case, sailing a little faster is the best way to transport more cargo in the same time, and thus complete more jobs. In fact, increasing speed is the short-term version of building new ships: it virtually creates more carrying capacity instantly. Building a ship takes months or years, so it can't be used to respond to sudden changes in demand.

Multihulls lose in displacement mode

[garyebickford]

Now, what I wonder is, would a cargo vessel be less polluting if it used a multi-hull design to reduce drag

Multihulls are very good at going fast - as long as they don't have to push a lot of water. Their advantage disappears rapidly when the weight goes up. I am in the process of getting into cruising (I have a 40 foot sailboat I'm refitting), so I've followed the progress of multihulls for a while. Small multihulls such as for cruising and other recreational applications work well because they provide a lot of interior space, and a certain type of stability (although there are costs involved), and they are fast - but many cruisers have found that once they pile on all the junk you need to live on a boat, the cats sink lower in the water and slow down.

Boats in displacement mode are _very_ efficient movers of mass, as long as you don't try to go to fast. Most of the energy that is expended at the front of the boat moving the water out of the way is recovered at the back of the boat, as the water moves back into place. The faster you go, the more water is pushed vertically out of the surface, and most of that energy is lost. And when you get close to 'hull speed' (where period of the bow wave becomes close to the length of the hull), you rapidly multiply the energy required - you're basically always driving 'uphill'. The purpose of the big bulb on the front of big ships is to length the effective hull and increase the hull speed. But drop the speed to just a bit below hull speed, and you are back into the efficient displacement mode again.

the logic is cost and jurisdiction

[SuperBanana]

I think the logic is that these heavy emissions actually sink into the ocean in international waters at diffuse levels not harmful enough to do damage (also that it would significantly increase the cost of all overseas goods).

I think the logic is that in international waters you don't answer to anyone, and you can burn the cheapest fuel your engine will tolerate.