The future of maritime propulsion

[darthgently]

1 hour ago, AckSed said:

To drag the topic back in line, here's a Scottish lake fisherman who converted his little boat to run on solar and batteries:

tl;dw The conversion was not that difficult, it has about the same capacity as a middle-of-the-road Nissan Leaf, and he doesn't go many miles, so many days in the summer he doesn't need to charge. It was the paperwork and regulation he had to deal with that was really challenging.

If you think about it, coastal fishing boats like this are good candidates for electrification.

And to drag it back again, he should have made it a multihull.  Would have been more efficient in this case for sure

Edited October 8 by darthgently

[farmerben]

The Scottish guy is dependent on shore power just not every day.

If I were Fletcher Christian, I'd learn the Polynesian technology for boat building rather than try to make metal nails and so on.  A 30m catamaran with over 2m of freeboard sounds totally plausible to me using traditional methods.

[darthgently]

13 minutes ago, farmerben said:

The Scottish guy is dependent on shore power just not every day.

If I were Fletcher Christian, I'd learn the Polynesian technology for boat building rather than try to make metal nails and so on.  A 30m catamaran with over 2m of freeboard sounds totally plausible to me using traditional methods.

Ships in the age of sail did not use nails typically.  Not for main structural things anyway.  They used joinery like dovetails, peg and hole, and binding with cordage.  I think nails may have been used to attach copper sheathing below the water line which prevented growth on the hulls, once this was discovered.  Iirc, they are not iron nails, because of salt, water, and rust.  Maybe bronze or copper?

It is important to remember that the western world has “tradition” also

European ships in the age of sail could be fully repaired anywhere that big enough wood could be found; no need to blacksmith nails.  It was a military requirement

Edited October 8 by darthgently

[darthgently]

Actually, I’m checking myself now.  Lapped hulls, like from Scandinavia, may have use some nails on the hull planks

Ok, hull planks, especially lapped planking, where the edges overlap, were commonly nailed with metal nails, but as I remembered most “nails” elsewhere were wooden pegs often called “treenails”.  

I’m curious how hull planking is done, if it is done, elsewhere in the world traditionally.

Polynesian hulls were made from hollowed tree trunks, so no planking required, but size limited

Edited October 8 by darthgently

[farmerben]

23 minutes ago, darthgently said:

Actually, I’m checking myself now.  Lapped hulls, like from Scandinavia, may have use some nails on the hull planks

Ok, hull planks, especially lapped planking, where the edges overlap, were commonly nailed with metal nails, but as I remembered most “nails” elsewhere were wooden pegs often called “treenails”.  

I’m curious how hull planking is done, if it is done, elsewhere in the world traditionally.

Polynesian hulls were made from hollowed tree trunks, so no planking required, but size limited

Polynesians did piece together their hulls sometimes with intricate joinery to bond the bow and sterns, and side planks to raise the freeboard.  They were lashed together and the seams were stuffed with breadfruit tree bark, which seems to have been good watertight caulking.   Dovetail joinery and wooden pegs they knew of also.  Some of the master woodworking was a closely guarded secret held by certain lineages.  

 

[darthgently]

14 minutes ago, farmerben said:

Polynesians did piece together their hulls sometimes with intricate joinery to bond the bow and sterns, and side planks to raise the freeboard.  They were lashed together and the seams were stuffed with breadfruit tree bark, which seems to have been good watertight caulking.   Dovetail joinery and wooden pegs they knew of also.  Some of the master woodworking was a closely guarded secret held by certain lineages.  

 

Those craft are beautiful

[farmerben]

Back to modern times, the material most suitable for building multihulls today is aluminum.  Your other choices are carbon fiber, steel, fiberglass, wood, etc.  Aluminum alloy is much cheaper than carbon and much more corrosion resistant than steel.  What we need is robots who perform the function of the English wheel, weld, and so on.  

 

[StrandedonEarth]

1 hour ago, farmerben said:

Back to modern times, the material most suitable for building multihulls today is aluminum.  Your other choices are carbon fiber, steel, fiberglass, wood, etc.  Aluminum alloy is much cheaper than carbon and much more corrosion resistant than steel.  What we need is robots who perform the function of the English wheel, weld, and so on.  

 

Hmm, yes. Here in BC, in the 90’s, the govt wanted to build some new ferries for the Vancouver Island runs, so they built three PacifiCats, dubbed “FastCats;” aluminum-hulled catamaran ferries. They were built in local shipyards, which required training the shipyard workers to weld aluminum. Naturally, they were over budget, costing some C$400M (90s $) for the three. And as it turns out, the wake (and the damage it did to nearby shorelines) was horrendous, even at the same speeds as the older ferries. So it wasn’t long until the project was cancelled, and they were eventually sold for a mere $13M. 

Okay, my memory was a little spotty. Here’s the Wikilink to fill in the blanks: https://en.m.wikipedia.org/wiki/PacifiCat-class_ferry

[AckSed]

China is trying out this battery thing on a container ship: https://electrek.co/2024/05/02/fully-electric-10000-ton-container-ship-begun-service50000-kwh-batteries/

COSCO Shipping Green Water 01 is a small river-to-sea container ship that plys the Yangtze from Shanghai to Nanjing with 700 Twenty-foot Equivalent Units, but its most interesting feature is swappable batteries. The batteries are in containers themselves, each holding 1.6MWh, and while it typically carries 24 of them (38.4 MWh), it can carry up to 36 (57.6 MWh) if it needs the range and/or power. With containerised batteries, it doesn't need to hang around to recharge and it can use the same port infrastructure: unload cargo, unload depleted batteries, reload fresh batteries, reload cargo, go. The second one is on order.

We could go further. I found an article in Nature: Rapid battery cost declines accelerate the prospects of all-electric interregional container shipping (2022)

To skip to the end, it reckons that, with lithium-iron-phosphate batteries at $100 per kWh:

Quote

In the baseline scenario, the TCP of a battery-electric ship is lower than that of the incumbent ICE vessel only for ship classes larger than 8,000 TEUs over voyages of less than 1,000 km. Over longer voyages, the additional cost of the battery system, increased power requirements and charging infrastructure outweighs the savings from fuel switching and the efficiency gains of direct electrification. However, if the environmental costs of NO_x, SO₂ and CO₂ are considered, the cost-effective range increases to 5,000 km across all size classes given the high emissions rates of HFO relative to the emissions intensity of the US grid.

They also note:

Quote

We find that minimal carrying capacity must be repurposed to house the battery system for most ship size classes and along short to medium-length routes. For a small neo-Panamax (~7000 TEU) containership, representing an average containership in the global fleet, the volume required by the battery system is less than the volume currently dedicated to the ICE and fuel tanks for routes under 3,000 km.

Like SSTO rockets, being big is good. The percentage cargo lost to batteries increases more slowly as the ships grow bigger, even though the gross mass given over to batteries has increased. With an 18,000TEU container behemoth that could sail to New York from Shanghai (20,000km), that's just under 20%. It's a horrific amount of course, but it could be done.

If there is an improvement in the future in battery energy density to 1,200Wh per litre, then the case improves substantially. Even the smallest 1000TEU 'feeder' ships only lose 30% of their capacity going the longest 20,000km routes, while the behemoth loses 5%, and it improves to positive amounts over short trips of 2000-5000km depending on the class.

As of Feburary 2024, the lowest average price CATL is supplying to car manufacturers is $69.53 per kWh. And there is overcapacity leaking out of the Chinese companies' ears.

[kerbiloid]

19 hours ago, farmerben said:

Bad for reefs.

Washed reefs - happy swimmers.

19 hours ago, farmerben said:

How much horsepower does that thing have?

One sea horsepower, I guess.

Spoiler

 

17 hours ago, darthgently said:

Yes, this would have the opposite effect as oil.  Sailors of yore would dump oil during storms to drastically reduce spray and wave height in their vicinity.  Surface tension is a silent hero.  Soap would have the opposite effect and all this has an effect on skin friction.

Soap will neutralize the floating oil from the tankers.

Two evils will neutralize each other.

12 hours ago, farmerben said:

Nice boats.

When you own the imported steel axes and saws.

Wait, whether this is made by stone or bloom iron axes?...

10 hours ago, AckSed said:

little boat to run on solar and batteries

I guess, a gasgenerator boat would work on firewood and make less carbonic footprint than the solar panel and the batteries production and replacement.

Also, while the batteries tend to burn and explode in water, the firewood is an additional escape option.

8 hours ago, farmerben said:

Polynesians did piece together their hulls

With what tools? Archaic or modern?

With the modern ones everyone could build this. But then it's just a modern design.

That cannon on the previous picture looks so frustrating...

[farmerben]

6 hours ago, kerbiloid said:

 

With what tools? Archaic or modern?

With the modern ones everyone could build this. But then it's just a modern design.

That cannon on the previous picture looks so frustrating...

I'm not sure what tools.  I've picked up tidbits like they used sharkskin for sandpaper.  The red boats above I think are modern replicas of boats that were built in the late 17 or early 1800s.  Even if you assume metal axes and metal chisels, it's still pretty impressive.  For that matter the totem poles of the pacific northwest are impressive carvings if you wanted to make one without metal tools.  

One source I read said Europeans used to lash hull planks together with leather until the Vikings invented the technology of nailing planks to the hull.  The Romans appear to have used mortise and tenon (peg or biscuit) joinery to bond planks edge to edge.  Anyhow that is an astonishing number of skilled man hours that go into building a ship, akin to building a temple.  The Viking clinker method sped things up considerably.  

Metal axes and knives were the first things traded by early Spanish explorers.  One preferred method for introducing yourself was to hang a tomahawk in a tree some distance from a village.  The next time you return sit still under that tree with a blanket full of trade goods.  Indigenous cultures almost universally understood and wanted to trade.

[Nuke]

nuclear powered megafreighters. wont go through any canal but can stock every walmart in a reasonable sized city.

[TheSaint]

12 hours ago, Nuke said:

nuclear powered megafreighters. wont go through any canal but can stock every walmart in a reasonable sized city.

The problem is that nuclear-powered ships aren't cost effective. Only four nuclear-powered merchant ships have ever been built, and the chief takeaway from them was that there was no way to make a profitable nuclear-powered merchant ship. The reason the military uses them is because the military isn't concerned with being cost effective. For proof see, well, just about anything that the military does. And even given that the US Navy stopped using nuclear power for cruisers because it was more efficient to power ships of that size with gas turbines.

I seem to remember a bunch of design studies from back in the 90s about using vertical wind turbines to drive a conventional screw. So the ship is wind-powered, but it can travel in any direction, it isn't restricted like a rigged sailing ship. Slow, but if you make the ship autonomous and only use it to ship low priority cargo, you don't really care.

[DDE]

4 hours ago, TheSaint said:

The problem is that nuclear-powered ships aren't cost effective. Only four nuclear-powered merchant ships have ever been built, and the chief takeaway from them was that there was no way to make a profitable nuclear-powered merchant ship. The reason the military uses them is because the military isn't concerned with being cost effective.

Not entirely true. Apparently nukes were studied for the Arleigh Burkes and assuming somewhat higher oil prices, they won out.

Do not underestimate the regulatory nightmare the nuckear freighters had to go through, too. Sevmorput' was never really allowed anywhere but North Korea.

[farmerben]

The chances of a nuclear accident are too high for this sort of thing.

Meanwhile an electrical propulsion system that takes up less volume than an ICE is not necessarily better.  What matters is the weight and the amount of extra water displaced.  The engine rooms on conventional ships are huge and mostly empty space.  

Shipping containers are typically loaded to 25 tones or less.  On US roads that is about the maximum weight without special permits.  That's about half full with lithium batteries.  Cargo ships also like to load the heaviest containers at the bottom and empties on top.

[AckSed]

On 10/10/2024 at 10:00 AM, farmerben said:

Meanwhile an electrical propulsion system that takes up less volume than an ICE is not necessarily better.  What matters is the weight and the amount of extra water displaced.  The engine rooms on conventional ships are huge and mostly empty space.  

Shipping containers are typically loaded to 25 tonnes or less.  On US roads that is about the maximum weight without special permits.  That's about half full with lithium batteries.  Cargo ships also like to load the heaviest containers at the bottom and empties on top.

The paper cited knows this. It also said that:

Quote

The distribution of additional weight also impacts the hydrodynamics, aerodynamics, stability and energy consumption of a vessel. Internal combustion engine (ICE) vessels use a ballast system whereby water tanks charge and discharge depending on the cargo load to distribute weight and counteract buoyancy. Case studies of fully electric or hybrid propulsion systems suggest that ballast systems can be partially or fully replaced by [battery energy storage] systems without substantial impacts to symmetry (trim) and balance by distributing battery components throughout existing void, mechanical and ballast spaces. Furthermore, BES systems do not need to be arranged around a central drive shaft and can be more flexibly configured within the vessel’s interior.

So on one hand it's slightly less flexible as you're moving bricks of ballast of a set weight, on the other you can distribute them more flexibly than a tank of fuel or a massive engine and driveshaft. You also lose mass as you burn fuel. In contrast, while the mass of batteries is 'dead' weight, it also doesn't change over time, making it more predictable.

This will take time to learn, but it's not insurmountable to learn to live with. You have to either change the order of operations (unload cargo then unload drained batteries) or have more powerful chargers that can charge over the 30-60 hours it's in port. The dockworkers have to figure out the distribution of cargo anyway so they know how much ballast to take on and in which tank. Water tanks can still be used for trim.

Note: This isn't a one-size-fits-all, more 'this size currently fits up to 5000km range small ships that load 7650TEU, with a corresponding 1m increase in draught'. Bigger ships with longer range may still have to burn fuel or be hybrids. In the future, though, with better batteries or cheaper ones... the case for longer-range full-electric ships closes.

Edited October 11 by AckSed
Added time for charging

[tomf]

On 10/8/2024 at 8:55 PM, darthgently said:

 I think nails may have been used to attach copper sheathing below the water line which prevented growth on the hulls, once this was discovered.  Iirc, they are not iron nails, because of salt, water, and rust.  Maybe bronze or copper?

I've dived the wreck of a late 18th century warship, HMS colossus and the most notable remains other than the canon are the half meter long copper nails for the copper sheeting. They were terrifyingly sharp.

[magnemoe]

38 minutes ago, tomf said:

I've dived the wreck of a late 18th century warship, HMS colossus and the most notable remains other than the canon are the half meter long copper nails for the copper sheeting. They were terrifyingly sharp.

Archaeologists has cut themselves on bronze age swords and daggers. Sheath was leather or wood and rotten away but edge is still sharp. 
Still half meter long nail, they are just to keep the plate on? The length indicate structural purposes. 

[TheSaint]

On 10/10/2024 at 12:24 AM, DDE said:

Do not underestimate the regulatory nightmare the nuckear freighters had to go through, too. Sevmorput' was never really allowed anywhere but North Korea.

Well, yeah, that's all part of the equation when it comes to "cost effectiveness". With a nuclear-powered vessel your maintenance costs go up, your crew salaries go up, your port fees go up. You're not allowed to discharge primary loop coolant overboard anywhere at sea anymore, so you have to store it onboard and transfer it in port to a decontamination facility, that's an added cost. Your midlife overhaul is now years instead of months, and that is downtime that the ship isn't earning money, so that needs to be calculated into the cost of ownership as well. It isn't just a simple matter of trading the cost of the reactor for the cost of fuel oil.

[farmerben]

Given the shortage on nuclear development on land, I see no reason to prioritize it on the water.  Everything on boats break much more often due to the constant wave motion.

Actually dirty maritime fuels reduce global warming due to the aerosol effect. 

https://www.livescience.com/planet-earth/climate-change/cutting-pollution-from-the-shipping-industry-accidentally-increased-global-warming-study-suggests

[farmerben]

Another idea.  What about using wood?  Very little wood is "wasted" at saw mills, but more of it goes into fuel than engineered products.  The engineered wood products require process heat after all.  Anyway when you saw lumber anywhere from 25-50% of it ends up as wood chips and they will oxidize eventually one way or another.

[magnemoe]

3 hours ago, farmerben said:

Another idea.  What about using wood?  Very little wood is "wasted" at saw mills, but more of it goes into fuel than engineered products.  The engineered wood products require process heat after all.  Anyway when you saw lumber anywhere from 25-50% of it ends up as wood chips and they will oxidize eventually one way or another.

Wood chips are pretty common for heating here in Norway.  Benefit is that its an waste product and you can automatically feed it. You can get it both for an house or an heating station who often also have other sources. 
My sister daughter apartment bloc is heated by one. 
For ships, no you have to go back to steam turbines, worse its less energy dense than coal. You could run an coal powered ship on wood if no coal but it was less powerful and you probably get more sot and waste. 
 Also loading, storing and using the stuff. Yes you could automate it but oil you can just pump. Most ships moved to oil after WW 1. For liners it was more expensive but you could reuse the firemen cabins as 3rd class cabins. 
And refueling was much faster and cleaner. 

[farmerben]

Given that weight is a big issue and the square cube law.  This could be a partial solution for ships.

[farmerben]

On the Mississippi river the towboats do not stop to refuel.  Tender boats come out and refuel them with diesel in motion.  I wonder to what degree you could do the same thing on batteries?  The big towboats use about 10,000 kW of power.

[Kerbart]

Windpower doesn’t scale well, but the main reason container ships are large is because of fuel efficiency. A wind operates vessel has far less need to be mammoth sized.

Besides that, container lines work with hub-and-spoke models that make airlines seem like child play. So while green shipping for deep ocean transport will likely focus on alternative fuels, wind power for the far smaller feeder vessels could definitely be an option.

Liquified gas is also a good option and while it does not address CO2 it does address the biggest issues with marine propulsion, sulpher and soot.

And finally, the returns on cleaning up ocean shipping are relatively small because it is ridiculously efficient, The CO2 cost of transporting a set of sneakers from SE Asia to a sports store in Ohio are mostly made up of trucking. Marine transport may be 99% of the distance but it’s a smaller part of total CO2 production