How to design a sailing ship for the 21st century? | Hacker News Reader

How to design a sailing ship for the 21st century?

lowtechmagazine.com

85 pointsrudenoise63 comments

I hope we get rid of cargo ships that burn matter. But sails are too high maintenance to be scalable.

Last year, as an experiment I've launched a tiny solar-powered boat ([1]). Ultimately, it was too small and underpowered only making ~900km ([2]) before dying.

I hope to build a bigger drone boat next, hopefully with an ability to move up to 1 tonne of cargo. Apparently, it's possible, but (unfortunately) requires very delicate engineering.

For bigger boats solar does not seem to scale. It appears that nuclear is the ultimate future for megaships.

1. https://imgur.com/a/eKlLCNg

2. https://storage.googleapis.com/samofly/track/index2.html

This. Anachronism is not the answer. These newly built tall ships will never be anything more than in essence a vanity project for brands that want to highlight their environmentalism.

If you want an efficient modern cargo sail ship, you should start with freestanding self trimming wingsails. These have roughly 3x more lift vs drag at the same sail area. But far more importantly: they can be controlled entirely by deflecting a small control surface, similar to the rudder on an aircraft. This can be automated nearly trivially with commodity hydroelectric actuators, redundant electronics, etc.

Making those out of a sustainable material vs the common composites is an open project. But I strongly suspect even using modern materials, over the lifetime of the ship, such a ship would have better net carbon footprint than modern tall ships, if you're honest about the staggering amount of labor that goes into building and operating tall ships, and the footprint that has.

We are going to have to think of a different way of accessing the cargo.

Cargo ships as currently built cede the entire middle section of the boat to cranes. Cranes they won't see until the end of their voyage, or the beginning of the next. The whole rest of the time you can't use the vertical axis for anything else.

Things that slide around tend to break loose in heavy weather, and boats don't stay afloat if the center of gravity moves too far, so sideways seems like a bad idea. I don't know what the solution is, exactly.

Depends on the ship. Container ships are just one type. Bulk cargo and stuff like car transporters remain relevant too.

But in the case of container ships, they have frames every so often to stabilize and secure the load. Those are the natural tie in point for wing sails. This is a relatively straightforward naval engineering problem. CG vs Center of Lift has been well understood since the 1800s.

Fixed sails won't be viable for container and bulk cargo ships due to the need for unobstructed access. They might be able to make limited use of kite type sails for running downwind.

Sails could be more viable for tankers and car carriers. Those don't rely on cranes for loading and have more free space on deck.

You could rotate it out of the way in port, assuming you can keep other ships from running into them (I've seen one fixed sale design that collapses like an antenna), but there are wear and tear problems with a mast that is not fixed, aren't there? Especially given the direction and magnitude of the forces we're talking about.

I have a few reservations about nuclear on ships:

1) Nuclear reactors produce waste that needs long term storage. There are lots of hypothetical / partial solutions for this and a lot of nuclear waste sitting there in temporary storage patiently awaiting the day that this problem is actually solved. Adding more waste to that pile is not a great idea.

2) Ships go to sea. The sea is treacherous. Meaning that waste might end up at the bottom of the sea when ships sink.

3) Seas have pirates. E.g. the coast of Somalia is a security risk. Pirates and nuclear reactors are not a great combination. Pirates with Muslim extremist backgrounds even less so. Basically, nuclear powered boats are dirty bombs waiting to get hijacked.

Burning fossil fuels is the problem that needs solving. However, burning synthetic fuels is perfectly fine and engines don't really care how the fuel is created. Synthetic fuels can be produced using clean energy and then pumped in large storage tanks on ships; very much like is the practice today with normal fuel. It's the obvious future. Hydrogen is an obvious candidate for this and there are multiple companies working on this and a few prototypes already sailing. Add some solar and wind to the mix and you get some efficiency gains. Other synthetic fuels are feasible as well. Even diesel could be synthesized eventually. The main challenge is building the infrastructure that is going to generate enough fuel at reasonable cost.

There are a few drone ship operators out there. They are not used for cargo and quite small but it works. These guys (https://www.saildrone.com/) use solar and wind powered autonomous drone ships for months long operations.

Nuclear may be part of our energy future, but security concerns and operating costs make it impractical to put reactors onboard civilian merchant ships. They can't afford to pay multiple armed security guards and trained reactor operators. Plus some countries don't even allow nuclear vessels into their ports.

A more realistic solution would be to use land based reactors to manufacture carbon neutral synthetic liquid hydrocarbon fuel. Then burn that fuel in the ships as an alternative to fossil fuels.

I'd be interested to see the numbers on this.

How much diesel-equivalent fuel could a 1GW nuclear power plant create in one year?

Here's my back of the envelope attempt.

1000MW * 0.9 capacity factor = 900

900 * 24 * 365 = 7,884,000MW

7,884,000 * 0.3 = 2,365,200MW electricity to liquid fuel efficiency[1]

2,365,200MW * 1000 = 2,365,200,000kW

2,365,200,000 / 10 energy content of 1L of diesel being ~10kWh

236,520,000L of diesel per year from a 1GW power plant.

Australia alone uses something like 33,000 megalitres of fuel per year (that's not all diesel, a lot of it would be petrol, but close enough).[2]

So Australia alone would need something like 140 x 1GW nuclear-to-diesel plants.

Did I do something wrong here? That seems like a lot.

This[3] says Australia has electricity generating capacity was 66.5 gigawatts (2017 number), so my 140GW estimate to cover Australia's transportation fuel requirements by electricity-to-diesel seems within the correct order of magnitude.

1. Semi-educated guess from https://en.wikipedia.org/wiki/Power-to-gas#Efficiency

2. https://www.abs.gov.au/statistics/industry/tourism-and-trans...

3. https://www.world-nuclear.org/information-library/country-pr...

Rather than have one reactor per ship, perhaps you could have just a few ships with reactors? Regular electrically-powered ships would tether themselves to the reactor ship, and they'd cross the ocean in a large convoy. The tether would supply electrical power.

That wouldn't work in any sort of heavy weather. And very few ships follow the same route at the same time for convoys.

> But sails are too high maintenance to be scalable.

I'm not sure how true this is, as a number of sail-assisted designs are already in use around the world, and have been for at least a decade. There are even several insurance classifications for large-scale cargo ships that incorporate the various possible sail-assisted architectures.

I wonder if electric ships could be a reasonable option? I don't have enough of the relevant numbers to do the math on whether a modern cargo container ship with some fraction of its mass dedicated to (perhaps) lithium iron phosphate batteries at about 150 watt hours per kilogram would be able to go any reasonable distance.

If we assume for the sake of argument that it's not enough for most reasonable-length routes, maybe if there was charging infrastructure at regular intervals that would help? I'm imagining for example a ship crossing the Pacific from the U.S. to China, but stopping in at Hawaii, the Marshall islands, and the Phillipines to charge. Maybe not even in a port; maybe there'd be power lines that run out to buoys that have the maritime equivalent of a DC fast-charger.

Also, one could imagine overhead lines being installed over the Panama and Suez canals. Ships could reach up with pantographs and charge their batteries as the traverse the canal.

The extreme case would be to have power lines that stretch from one continent to another, and ships cross whole oceans without ever unplugging. I'm not sure how that would work, exactly: floating cables? Cables that run along the sea floor, but the ships run an extension cord that drapes down to meet it? Lots of mechanical problems that would have to be solved.

Even with charging infrastructure only available in some places, if ships were configured with diesel engines that can take over when the batteries are dead, running off of batteries at least part of the time could reduce the fuel consumption by quite a lot.

That's really cool! It looks like you're in the SFBA (or at least launched your boat from nearby), so are you familiar with Sofar and Saildrone? Do you have a way for people to follow what you're doing, or pitch in? I'd be interested in this (contact info in my profile).

Thanks for the kind words!

Yes, I am in SFBA; I know about Saildrone; Sailbuoy, Liquid Robotics and a few other similar companies pursuing small data-collection drone boats. I didn't hear about Sofar yet - thanks for the link.

As a full disclosure, the boat I launched was made under collaboration with Blue Trail Engineering ([1]) known for SeaCharger ([2]). All cool parts on the photo are from them; my parts were camera / extra satellite modem / some cloud autopilot. I am way less cool than Damon from Blue Trail Engineering.

As for my solar drone boats hobby, it's so slow moving that there's nothing to follow at the moment. If I get the second boat out of the CAD stage, I would probably get something on my low-profile youtube channel ([3]). But I would not expect anything too soon: bigger boat requires very careful engineering, and with my limited hobby budget it will take time.

Anyway, thank you for the words of encouragement. :)

1. https://www.bluetrailengineering.com/ 2. http://www.seacharger.com/ 3. https://www.youtube.com/channel/UCXLwwf3muIhUs7zYIbRTHNw

Do one these things last in Ocean waters? Sharks? Hurricanes? Random accidents ? Petty vandalism and piracy?

Can you hit 10 year life time if you use commercial grade components?

Larger sailing vessels (10m+) are actually moving towards solar + hydroelectric with lithium batteries (48v) to power electric engines and generators. Sailing with wind power uses the hydroelectric generators and solar. Motor sailing uses solar and you regen a little bit from hydro or a wind turbine.

https://www.sailinguma.com/

Dan and Kika of Sailing Uma themselves recognize that this setup is not for everyone. Here's an interview with them on Sailing Ruby Rose on the subject:

* https://www.youtube.com/watch?v=xOAXi5huV1U

A better solution, for the time being, may be what Rebuilding Tally Ho is doing and use a hybrid engine:

* https://www.youtube.com/watch?v=xohxmwPfctg

He specifically chose a Beta Marine (marinized Kubota) diesel that has an electric motor/alternator connected to a 48V battery bank. If either the mechanics or electrics go, he can use the other. For short jaunts, like in and out of harbours, he can use the electric system to preserve fuel. The system has re-gen capabilities under sail.

More pricey though.

Awesome thanks for that! I wasn’t aware of Beta Marine’s hybrid engine. Looks awesome but definitely pricey.

The article essentially dismisses lithium batteries as non-sustainable.

Which is dumb, because the "saltwater" batteries have manganese cathode and titanium phosphate anode... doesn't sound radically different than lithium iron phosphate.

There were a number of fires in boats at the beginning of using lithium batteries that put off many people from using them.

Because "lithium" means a whole category of things. See this mega-thread that was started in 2011 when people will still feeling things out:

* https://www.cruisersforum.com/forums/f166/lifepo4-batteries-...

The chemistry of LiFePO4 was settled on (versus something that used cobalt, à la Boeing's 787), and the risk of fires has been reduced considerably. You're more likely to have a boat fire from bad DIY electrical cabling and a lack of fusing.

For more than you ever wanted to know about marine electrical/electronics see Jeff Cote's channel:

* https://www.youtube.com/user/pacificyachtsystems/videos

All batteries are non-sustainable. They burn out eventually.

>I hope we get rid of cargo ships that burn matter.

What would be wrong with a hydrogen fuel ship or a biomass fueled ship?

Very cool. How did you communicate with it? Or did you follow it in a larger boat?

Iridium RockBlock. Bandwidth costs were insane (~$1/KB).

Two of the last paragraphs:

> All of this is technically possible, and as we have seen, it would produce less in emissions than the present alternatives. However, it’s more likely that a switch to sailing ships is accompanied by a decrease in cargo and passenger traffic, and this has everything to do with scale and speed. A lot of freight and passengers would not be travelling if it were not for the high speeds and low costs of today’s airplanes and container ships.

> It would make little sense to transport iPhones parts, Amazon wares, sweatshop clothes, or citytrippers with sailing ships. A sailing ship is more than a technical means of transportation: it implies another view on consumption, production, time, space, leisure, and travel. For example, a lot of freight now travels in different directions for each next processing stage before it is delivered as a final product. In contrast, all sail cargo companies mentioned in this article only take cargo that cannot be produced locally, and which is one trip from producer to consumer.

This speaks to me. I see much more conversation around "how can we use technology to remove the negative environmental impacts from our lifestyles?" than I do around "how can we change our lifestyles to cause fewer negative impacts?"

It's also complete nonsense. Invent a worse technology so people will use it less. If you can compel people not to use the faster ships, then just compel them to use those less instead!

Because the latter isn’t a sustainable solution to the problems we are facing. The environment can’t support all of the current population at any kind of modern lifestyle.

Unless “changing lifestyles” is “give up all daily transportation, heating, cooling, meat, and 99 percent of electricity”, it’s not gonna cut it.

Better zoning could eliminate a huge amount of commuting emissions. A cultural shift away from in-person meetings as signalling, and travel as a substitute for personality, could eliminate a huge amount of air travel emissions. Meat consumption can be drastically reduced. The changes we need aren't actually all that big.

I believe you are over estimating the amount of change required. Fifty years ago, or so, consumption was much lower without doing away many of those things.

A natural gas powered container ship would probably have lower emissions per unit of cargo moved than the proposed "eco" sailing ship, which has low cargo capacity by modern standards. The big problem with cargo ships from a pollution standpoint is that they run on really crappy "bunker oil C", which is about halfway between jet fuel and asphalt. Heavier than seawater. One of the biggest sources of preventable pollution.

And, come on, then want to haul sails by hand on a ship of that size? And use rowing machines to generate electric power? They'd need a huge crew.

Liquid natural gas carriers often run on their own natural gas. There a few natural gas powered freighters now, but they're built in the US for the run to Puerto Rico, which, under the Jones Act, is limited to American ships.

The latest ships used by CMA-CGM use LNG, and they're not planning on using heavy fuels anymore.

https://en.m.wikipedia.org/wiki/Jacques_Saad%C3%A9-class_con...

Exactly. Also, they didn't seem to mention the speed difference between typical diesel ship and their proposed "Eco" ship. If it takes a week more that might be fine, but if it takes 5 times as long no one will use it for large scale commercial goods (perhaps there is a niche for transporting "Eco" products)

Natural gas has its own issues https://www.theverge.com/2021/5/6/22422824/natural-gas-infra...

90% of that is burying the lead that leaking methane is an issue. No shit, but moving from Bunker>LSFO>LNG is going to cause a net decrease in GHG emissions. Operators that have to focus on profit margins, not maintaining artificial monopolies can't afford to subsidize leaking equipment. Aliso Canyon caused a substantial investment in methane detection hardware thats in use. Next step is getting E&P co's to pay into a perpetual fund that monitors old wells.

Make it big, get it up out of the water.

The larger your ship is the more efficient it can be, and the less of it in the water the less energy is needed to push it.

So make big big ships with really really big sails. You want the ships to fly with just the keel in the water to steer against the wind.

You might think I'm joking or talking nonsense, but look up Alexander Bell's cellular geodesic kites, and Bucky Fuller's "Cloud Nine" floating city.

I think you're joking and talking nonsense. There are practical limits to the size of a planing or foiling vessel. This is just basic physics. Adding more sail area isn't helpful; at some point it's counterproductive and actually slows the vessel down.

Well ok. But my limited understanding of material science says no. For now at least.

Material strength doesn't scale well to go "properly big big" in the sci-fi sense.

OTOH, I am constantly amazed by what material science keeps managing to do, so I have hopes that maybe one day your dream will be true.

Cheers!

Are you familiar with Bucky Fuller's concept of "tensegrity"?

https://en.wikipedia.org/wiki/Tensegrity

https://mymodernmet.com/tensegrity-architecture/

He pointed out that the struts could recursively be made out of tensegrity structures. Or you can make them out of balloons:

https://en.wikipedia.org/wiki/Tensairity

I was being a little coy in my previous comment. The structures I'm thinking of are more like kites than sailing ships. They would "dip a toe" in the water to tack, perhaps, but they would be aerial not marine in nature.

A. Bell lifted a man with his cellular geodesic kites. https://en.wikipedia.org/wiki/AEA_Cygnet

In any event, I hope my dream does come true one day. :) Cheers!

While not aware of the phrase tensegrity I have rarely seen various forms of "floating tables".

Initial thoughts:

- seems like a manner of construction to swap tensile strength in certain spots, thus allowing for an awesome "against intuition" visual effect.

- could be nice from a packaging point of view. Collapsible objects, the wiki link mentions the nasa ball robot.

- maybe it could shift Bill-of-Materials costs through smaller amounts of expensive extremely high compression/tensile capable materials to be offset by savings on larger amounts of cheaper other capable sections.

- I am not convinced it would allow the superstructures much sci-fi requires as the basics of tensile strength, compression strength are still in play.

- As mentioned in the tensairity article, if humanity could make a pressure withstanding, airtight object, say a sphere, around a vacuum with less mass than the air it displaces, we could have architectural "anti-gravity".

Including an airship with a toe in the water. :-)

Finally, I simply don't know enough.(Do we ever?) It looks cool and is worth investigating further. I am going to lose lots of time thinking about, checking out and printing out occasional bits from thingiverse now!

Cheers!

> - seems like a manner of construction to swap tensile strength in certain spots, thus allowing for an awesome "against intuition" visual effect.- seems like a manner of construction to swap tensile strength in certain spots, thus allowing for an awesome "against intuition" visual effect.

I recommend building physical models. It's hard to convey how strong and light these structures can be. Very "against intuition". :)

> - could be nice from a packaging point of view. Collapsible objects, the wiki link mentions the nasa ball robot.

https://en.wikipedia.org/wiki/Hoberman_sphere

https://www.nasa.gov/jpl/news/origami-style-solar-power-2014...

Yes. :)

> - maybe it could shift Bill-of-Materials costs through smaller amounts of expensive extremely high compression/tensile capable materials to be offset by savings on larger amounts of cheaper other capable sections.

https://en.wikipedia.org/wiki/Ephemeralization

Bucky again.

(Kevlar tendons and carbon fiber struts...)

> - I am not convinced it would allow the superstructures much sci-fi requires as the basics of tensile strength, compression strength are still in play.

I'm not an engineer, but we can already build some impressive structure w/o advanced materials. Cf. "bamboo scaffolding" (DDG image search: https://duckduckgo.com/?t=ffcm&q=%22bamboo+scaffolding%22&at... )

I'm imagining swarm cellular kite robots that can self-organize to create whatever size lifting body is needed. I'm thinking about things like how to move millions of people at a time (which we might want to do due to climate change, etc.)

Have you read Vinge's "Rainbows End" (sic)? ( https://en.wikipedia.org/wiki/Rainbows_End ) There are buildings in the story that are too flimsy to stand up without active control and feedback, something like that could work with these kite-bots.

> - As mentioned in the tensairity article, if humanity could make a pressure withstanding, airtight object, say a sphere, around a vacuum with less mass than the air it displaces, we could have architectural "anti-gravity".

We don't have to go that far (although it would be neat if we could, diamond vacuum bubbles?) Did you read about "Cloud Nine? https://en.wikipedia.org/wiki/Cloud_Nine_(tensegrity_sphere)

I've thought about this a lot but not yet gotten my act together enough to do it. I wrote up some of it here: https://lists.sr.ht/~sforman/heliotrope.pajamas/%3C202012290... ("heliotrope.pajamas" is my mailing list if you want to reach me in re: this stuff)

Well met!

Take the idea just a notch further and you've got yourself an ekranoplan.

https://en.m.wikipedia.org/wiki/Lun-class_ekranoplan

> The amount of cargo that was traded across the oceans in 2019 equals the freight capacity of 22.4 million EcoClippers. Assuming the EcoClipper500 can make 2-3 trips per year, we would need to build and operate at least 7.5 million ships, with a total crew of at least 90 million people. Those ships could only take 0.5 billion passengers (12 passengers and 8 trainees per ship), so we would need millions of ships and crew members more to replace international air traffic.

Interesting article but I'd like to hear about other large scale sail boat designs, perhaps even mega-catamaran sailboats..

These people are really serious:

https://www.youtube.com/watch?v=i2WKJtbm8yM

IDK how many forrests have to be cut down though.

>The EcoClipper500 has a carbon footprint of 2 grammes of CO2 per tonne-kilometre, which is five times less than the carbon footprint of a container ship.

And if that is not a testament how stupidly efficient container megaships are, I don't know what it is.

I'm surprised no-one has mentioned rotor sails yet https://en.wikipedia.org/wiki/Rotor_ship?wprov=sfla1

The best solution is to simply tax bunker fuel, at a rate that approximates its pollution cost.

Then the market will sort it out to find another optimum.

I would expect a 21st century sailing ship to have sails built like wind turbine blades, positioned autonomously.

Book recommendation if you found this article interesting (and haven't already read the book, a classic) :

Eric Newby, The Last Grain Race

https://en.wikipedia.org/wiki/The_Last_Grain_Race

Okay it's not cargo, but I've seen some innovative "eco" developments in the personal yacht space.

Take Daedalus yachts[0] for example, a USA built, lightweight (carbon fibre) sailing yacht with the aim of being zero emissions. They use a combination of solar, wind and hydrogen re/generation to get power for both the cabin and the drive system.

Perhaps a similar combination of technologies could be used to scale up commercial/cargo sailing ships?

[0] https://www.daedalusyachts.com/

Does anybody have a good book or good resources for nuclear powered merchant marine? Naively it makes sense that nuclear power could support much larger ships and go much faster than diesel, but i don't know how true that actually is.

The US tried this concept at one point with the nuclear powered NS Savannah, which was a cargo/passenger ship. Unfortunately it was already outdated by the time it was built, unable to accommodate the modular containers taking over the shipping industry. It was mostly a novelty at the time and was expensive to run.

Still though it seems nuclear would be a good fit for shipping. Most large ships use electric motors for their propellers anyways, and the US Navy has extensive experience deploying reactors in submarines. Theoretically you would only need to refuel such a ship every 10 years or so. Fears about terrorism or contamination will probably prevent such a ship from being made any time soon, not to mention the lack of infrastructure.

Large merchant ships don't use electric motors. The propeller is directly driven by a large diesel engine through a mechanical transmission because that is the cheapest and most efficient design.

They don't even use a transmission in most cases. The propeller is direct driven, the engine itself can be started in reverse to go astern.

Large cargo ships are displacement hulls (because they are 10x more efficient than planing hulls) but are limited to a top speed proportional to the square root of the length, so they will not be "much faster".

Apart from (Soviet) ice breakers Nuclear powered merchant ships haven't had a successful history. I guess politically most states don't want nuclear technology to spread or let nuclear material into the wrong hands - by their nature cargo ships travel and would be an easy target for hijacking.

https://en.wikipedia.org/wiki/Nuclear_marine_propulsion#Civi...

https://i.imgur.com/9anWCXD.jpeg

https://i.imgur.com/IpYrxLs.jpeg

https://www.amazon.com/Story-Savannah-Labor-Management-Publi...

https://www.gutenberg.org/ebooks/63584

monohull sailing ships need to heel

modern shipping is designed around stacked containers

Not so easy.

I did a deep dive into the container ship industry many years ago in order to understand unit economics and how certain technologies could improve the ecologic impact of this massive industry. It was very interesting. I learned a lot.

I see a lot of comments about going electric, hydrogen, solar, sail, some kind of hybrid, etc. I don't think any of this is near any time horizon I can name or recognize.

Why?

Cargo ships use something called "Bunker Fuel" [0].

What is bunker fuel?

Well, to put it simply, it is what's left after you take petroleum and distill it into various grades of gasoline, diesel, industrial oils, etc. It is often referred to as "the bottom of the barrel". Another way to think of it is that bunker fuel is the waste product. Some grades of bunker fuel are so thick you can walk on it and will only flow if heated. This should not come as surprise, asphalt is the next level down and that stuff is solid enough to make roads out of it.

Why did I say "not so easy"?

Because these ships are effectively burning the waste product from the manufacturing process that leads to all the fuels and lubricants we consume in massive quantities.

What does this mean?

If we stopped using bunker fuel next Monday, what would we do with the absolutely massive amounts of bunker fuel produced every year? Think about that for a moment.

Sure, hydrogen and electric sound "clean", but you would have a potentially larger ecologic disaster in having to dump bunker fuel somewhere. The bottom of the barrel isn't going to magically disappear just because we transition cargo ships to something else.

What to do then? It's a tough problem. One solution, maybe, I don't know, is to evaluate how efficiently and cleanly we might be able to burn bunker fuel on land vs. on a ship. My point is that we might be able to extract and use this energy in a super-clean way, to charge batteries or whatever. I haven't studied this at all. I would imagine that if we set out to truly create a super-clean process to burn bunker fuel on land for energy generation it could be a good path forward. I don't know how much better we could do on land (in terms of clean burning) than on a ship. I'd like to think we could do a lot better.

I do think the future is electric, in some form. What I can't see or predict is how we transition from today's reality to that reality. This isn't a case of just having to solve the containership problem, you have to solve the entire oil/fuel ecosystem because, if you don't, you are going to have astronomic amounts of bunker fuel (waste product) to contend with. This is how shifting cargo ships to electric could actually be worse for the environment than letting it be and working to make them as clean as possible. Weird, isn't it?

[0] https://en.wikipedia.org/wiki/Fuel_oil

Because of new sulphur regulations in 2015, many ships shifted from heavy oils to lighter ones. It's not a huge renovation. Costs more of course.

Ammonia (NH3) is the new promising carbon free fuel for ships.

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