[HN Gopher] Michelin Puts Puffy Sails on Cargo Ships
___________________________________________________________________
Michelin Puts Puffy Sails on Cargo Ships
Author : rmason
Score : 197 points
Date : 2021-06-27 06:22 UTC (16 hours ago)
(HTM) web link (spectrum.ieee.org)
(TXT) w3m dump (spectrum.ieee.org)
| baltbalt wrote:
| I have a hard time believing you can transfer 20% of the power
| through the upper deck without rethinking the whole structure.
| senectus1 wrote:
| ^this.
|
| especially if the ship is loaded with materials.
| hypersoar wrote:
| If it's like a conventional sailboat, the mast will go all the
| way down to the keel.
| bagacrap wrote:
| I would imagine the masts travel through the upper deck from
| their base which is bolted onto the frame, rather than being
| bolted to the outside deck.
| acidburnNSA wrote:
| In terms of cleaning up and decarbonizing shipping, nuclear power
| is a more natural fit in my opinion. Very high power density for
| long periods of time. Proven practicality and appropriate safety
| for decades by the Navy.
|
| To deal with ports not wanting them to come in, you can use
| ocean-faring nuclear powered tugs that hand-off long-haul cargo
| barges to electric or fossil tugs for the final 10 km.
|
| This was tried in the 1960s (see N.S. Savannah [1], Otto Hahn,
| etc.). Russia actually operates a nuclear powered cargo ship
| today (Sevmorput), though it does cause problems e.g. when the
| propeller breaks on the way to Antarctica and no shipyard will
| let you in [2].
|
| The key is to mass produce them in such a way that economies of
| mass production can be used to alleviate the challenges of
| nuclear costs. Interestingly, this also parallels with options to
| help decarbonize the world with shipyard-constructed offshore
| nuclear power stations [3].
|
| [1] https://en.wikipedia.org/wiki/NS_Savannah
|
| [2] https://thebarentsobserver.com/en/nuclear-
| safety/2020/11/mec...
|
| [3] https://whatisnuclear.com/blog/2020-01-26-offshore-power-
| sys... (disclaimer: my site)
| foepys wrote:
| I'm not sure you want to put nuclear fuel on average cargo
| ships. What happens when one gets hijacked?
| acidburnNSA wrote:
| Security and piracy would be a new challenge, but I still
| think it's worth it to avoid all the current killer air
| pollution and CO2 emission. You could make the core basically
| inaccessible except when in an outfitted maintenance shipyard
| and have a priority mobile security force to respond to such
| incidents. The ships should be designed to have a fail-safe
| sink function where it sinks and maintains the core integrity
| using seawater convection until a designed salvage operation
| can occur.
| 8note wrote:
| The bigger problem is sovereignty. Ships get detained
| sometimes when they're en route, or when they're stopped at
| Port.
|
| The mobile security force isn't going to be authorized to
| start a war
| rodgerd wrote:
| I, for one, cannot wait until Somalian pirates become
| nuclear-armed crime syndicates. I've always wanted to
| live in the worst bits of cyberpunk dystopias.
| patall wrote:
| The company SkySails developed a similar system (not inflatable
| though) around 2008-12 which reached projected fuel savings
| between 10-15%. Never fully comercialzed, likely due to similar
| problems as kite power generators.
| [https://en.wikipedia.org/wiki/SkySails]
| sshine wrote:
| It's like to know how they deal with presumed extra risk of
| tipping over. Can you flexibly let go of the sails if it suddenly
| gets windy, like the gecko's tail?
| BoxOfRain wrote:
| I suspect it works like any other sail. On an ordinary sailing
| boat you're aiming to balance the aerodynamic and hydrodynamic
| forces as efficiently as possible, if you're heeling over too
| much you can reduce the power produced by the sail by changing
| the sail's angle to the wind, by reefing the sail (which
| reduces the sail area exposed to the wind) or by changing the
| angle of the boat to the wind (a less upwind course means less
| heel).
|
| Sailing boats with a keel usually resist capsizing because as
| they heel over the keel is pushed to windward at a greater
| angle, increasing the righting force it provides to the hull.
| Additionally the greater angle of heel decreases the area of
| sail that's being exposed to the wind, further increasing the
| overall effect of the righting force. It would be interesting
| to see how these can be retrofitted to an ordinary cargo ship
| though, sailing boats are optimised for a particular amount of
| heel whereas as far as I'm aware cargo ships generally aim to
| avoid heel altogether as far as possible with large ballast
| tanks where water is pumped around.
| codetrotter wrote:
| I think sails will tear and masts will break sooner than the
| wind would be able to tip the boats over.
| dalbasal wrote:
| You're right. Sail ships are impossible. Too tipy.
| hansjorg wrote:
| Sailing ships have keels.
| mdtusz wrote:
| The presence of a keel isn't necessary - just righting
| moment. If you look at most very large sailing ships, their
| keel isn't a large protruding fin keel like on racing boats
| like you're imagining. A cargo ship has enormous righting
| moment just by means of its ballast - the windage of their
| hulls alone is enormous.
|
| I still don't think using traditional sails is practical
| though, and kites are a far more elegant and useful
| solution. They require far less cost and are easier to
| retrofit onto existing hulls, can be easily scaled up or
| down depending on wind conditions, and in the event of even
| catastrophic failure are pretty safe (i.e. if the kite line
| were to break). The biggest danger of them is the kite line
| falling in the water and getting fouled on the propellers,
| but this is a solvable problem.
| [deleted]
| bitwize wrote:
| The sails automatically retract if the ship encounters a bridge
| or other structure it needs to pass under. Presumably they
| could be made to do so if weather jeopardizes the sails or the
| ship with sails deployed.
| 1cvmask wrote:
| This is actually an update of an older idea that was shelved for
| cargo ships after oil prices dropped after the 1973 oil crisis.
|
| https://en.wikipedia.org/wiki/DynaRig
|
| The fancy sailing yacht Maltese Falcon, commissioned by the
| deceased billionaire VC Tom Perkins (of Kleiner Perkins fame),
| was built with that design:
|
| https://en.wikipedia.org/wiki/Maltese_Falcon_(yacht)
|
| Here is a book on the boat:
|
| https://www.amazon.com/Mines-Bigger-Extraordinary-Greatest-S...
| choeger wrote:
| I have the feeling that technologies like this (including these
| kites and also Flettner sails) are too little too late. While a
| 20% saving on fuel is great news for the operators of these ships
| (if the sails themselves are low-maintenance), the world as a
| whole seems to be moving off carbohydrates in the next two
| decades. For shipping this inevitably means to switch to green
| fuels (e.g., Ammonia). Once the production of such fuels has
| reached a certain scale, sails might not be necessary anymore.
|
| The reason here is the extremely low cost of energy from
| photovoltaics: We see less than $0.03 per kwh [projected prices
| for some currently planned large scale farms] - that's about $0.3
| for the energy of 1 kg of bunker oil. Bunker oil sells for about
| $300 to $500 per ton, so roughly $0.4 per kg. That means that a
| replacement fuel with more than 66% conversion efficiency could
| already be competitive right now. High Temperatur Hydrogen
| Electrolysis is reportedly available with 80% energy efficiency.
| As far as I know, there is no indication that solar costs could
| stop falling anytime soon, so in the next 20 years we will
| probably see it drop well below $0.01. So if I did not misplace a
| decimal somewhere, the future should be in relatively cheap
| large-scale green fuel.
| hellbannedguy wrote:
| These greedy Globalists are probally clamoring for the day
| diesel gas drops in price due to most everyone else trying to
| green. They will just need to act lije they care about burning
| fossil fuels, and happily pay for lower diesel fuel.
|
| Until then--they will do stunts like this in order to show they
| care. (20% savings in fuel is big though. "Stunt might be to
| cynical?)
|
| I feel the companies that use shipping are scared. They are
| afraid of tariffs/taxes tacked on to their cheaply made
| products if the public starts complaining.
|
| They got away with manufacturing in the cheapest country. We
| just gave up trying to buy reasonably priced products at home.
|
| I imagine they are very scared of their perceived culpability
| in Global Warming though?
|
| I am all for the sails. They don't seem copacetic with
| container ships though?
|
| The filthy loucres couldn't carry as many containers with
| sails?
| umvi wrote:
| > carbohydrates
|
| You mean hydrocarbons?
| jwdunne wrote:
| Yeah, that seems to be an error. There are more than a few
| claims about the effects of a ketogenic diet, but I don't
| think lower fuel costs is one of em!
| inglor_cz wrote:
| Well, if enough people lose their extra fat, at least the
| airlines may save some fuel when transporting them, no?
| jwdunne wrote:
| And/or using the extra energy levels to walk or cycle
| instead of drive, reducing fuel demand.
| pjc50 wrote:
| > For shipping this inevitably means to switch to green fuels
|
| Dunno, as with all of these things we have to look at the
| lifecycle; how long is a ship in service? How many are being
| built with non-hydrocarbon fuels, or converted, today? It's a
| very small number. Mostly short-haul ferries on government-
| influenced routes e.g.
| https://www.cruiseandferry.net/articles/scotland-explores-fe...
| animal531 wrote:
| Also, just looking at the wing it seems to block you from using
| 2/5'ths of the top of the ship, which doesn't offset the 20%
| gain.
| Retric wrote:
| I think your missing the key feature: _inflatable sails_.
| They don't take up much space when not in use.
|
| That said, ships aren't limited to container ships. Oil
| tankers have a lot of available deck space.
| kumarvvr wrote:
| Great analysis. I would like to add a few more points.
|
| Energy extraction from oil is typically a low efficiency cycle.
| ICEs are around 30% efficient. Gas Plants are around 40%
| efficient.
|
| Energy from solar -> batteries -> application usually hovers
| around 70 - 80% efficiency.
|
| Motors are around 98% efficient. That covers most of our
| requirements for manufacturing. Conversion of electricity to
| heat is almost 96-98% efficient.
| pfdietz wrote:
| Combined cycle gas plants are about 60% efficient (on a LHV
| basis).
|
| Large marine diesel engines can have a thermal efficiency >
| 50%.
| folmar wrote:
| > Energy from solar -> batteries -> application usually
| hovers around 70 - 80% efficiency.
|
| Nope, energy from solar is around 20%, batteries are at
| around 90% efficiency.
| creato wrote:
| The dollars per unit energy already includes this
| inefficiency of photons to electricity though. You are
| double counting it.
| jmartrican wrote:
| 20% savings on fuel is still good regardless of what fuel it
| is. So these sails seem relevant in a green energy world.
| signal11 wrote:
| > the world as a whole seems to be moving off carbohydrates in
| the next two decades.
|
| I know Keto and Atkins are popular but I'm not sure the world
| as a whole will move off carbs... :-)
| choeger wrote:
| Well, for a truly carbon-free society, everyone has to do
| their parts. So no pasta for you anymore after 2030 ;).
| MrYellowP wrote:
| It's not too late. I don't even know why you would think so.
|
| Even if it takes them a year to equip all their fleets with
| these sails, they'd still be saving money and fuel for the time
| until they're not needed anymore.
| hytdstd wrote:
| Without knowing the financials related to the product, it's
| really not possible to say that it's definitely worth it for,
| for example, 1 year of service.
| Closi wrote:
| This doesn't have to be _instead_ of Ammonia, and could clearly
| be _as well as_ Ammonia. If it decreases 20% on the current
| fuel, I don 't see why it wouldn't also decrease 20% of any
| future fuel.
|
| Besides, although it's a possibility that we will have abundant
| solar within 20 years, let's also build on the basis that we
| might not and solve the problem from multiple angles!
| pwagland wrote:
| Ops point was that if the cost of fuel drops by 75% (using
| the numbers from their comment), then things like sails may
| no longer be cost effective.
|
| For example, it saves 20% of your fuel cost, great! But its
| cost is 10% of your fuel cost. At current fuel prices, you
| still come out ahead, since you are saving more than you are
| paying.
|
| However, if fuel is 1/4 the cost of now, then you still save
| 20% of fuel cost, but the sails now cost 40% of your fuel
| cost... aka the sails now cost you money to run.
|
| To be clear, while these sails are profitable, they will be
| used. Op is just saying that they think they will become
| unprofitable sooner than expected.
| Retric wrote:
| Your assuming the only cost for Hydrogen/Ammonia fuel is the
| energy. Even if energy was free you still need to charge for
| infrastructure, workers, transportation, and profit.
| freeflight wrote:
| _> For shipping this inevitably means to switch to green fuels
| (e.g., Ammonia). Once the production of such fuels has reached
| a certain scale, sails might not be necessary anymore._
|
| Green fuels will need to ramp up their production to meet the
| demand, better actual efficiency (not just financial) means
| that ramp up wouldn't need to be as steep as the demand won't
| be as high so we will have an easier time actually filling that
| demand.
|
| It's a bit like not changing to more energy efficient light-
| bulbs based on the assumption that in 20 years green fuels will
| make electricity so affordable, and emissions neutral, that it
| allegedly won't matter.
|
| One could do that, but if the cheap green energy doesn't end up
| materializing in that time then you did nothing to reduce to
| problem and end even further removed from an actual solution.
| wffurr wrote:
| >> ships are a significant source of toxic air pollution in ports
| and coastal communities
|
| Exactly where these auxiliary sail systems are of no use. The
| only way to address this is short range electric power for use in
| harbors.
| [deleted]
| joshvince wrote:
| I wonder how many stacks of containers are no longer viable (and
| how many more journeys will be needed) on vessels fitted with
| those two enormous sails.
| gonzo41 wrote:
| I think the answer to that is to build it into a hightop
| container and make it the last on top of a large stack. Plug
| ship power into it and control from the main deck.
| pharke wrote:
| I don't think the physics checks out on that one.
| tomatotomato37 wrote:
| You could probably mount these on top of some sort of mast so
| the actual sail clears the containers. You'd lose the space the
| columns take but that's still a lot less containers lost than
| the picture suggests.
| darksaints wrote:
| The problem with using it for container ships isn't
| necessarily the height (although that _could_ be a problem,
| as retraction for bridge clearance requirements makes mast
| engineering a lot harder). The problem is heeling due to the
| wind. We already have a fairly large problem with containers
| falling off of ships and being lost at sea, and this could
| only make it worse.
| bbarn wrote:
| The concept rendering made me ask the same question. I have
| cargo ships parked out my windows, and that's a lot of space.
| Lex-2008 wrote:
| To my inexperienced eye, it looks like a ship to cargo
| unpackaged grain, not containers - see
| https://en.wikipedia.org/wiki/Bulk_carrier
| hef19898 wrote:
| It could also be feasible with tankers, gas or liquid.
| Jyaif wrote:
| I would imagine that they thought of that! For one, this could
| be used on tankers.
| pseudolus wrote:
| Rotor sails (large cylindrical sails that use the Magnus effect)
| have been deployed by Maersk and have been proven to result in
| fuel savings [0]. Years ago I believe Maersk also ran a test
| project where they deployed traditional sails on ships.
|
| [0] https://maersktankers.com/newsroom/norsepower-rotor-sails-
| co...
| fennecfoxen wrote:
| Experimental wind-assist sails of various sorts for modern
| cargo ships have been around at least a decade, and the
| question has generally been whether the fuel savings is worth
| the added capital and operational expenses of maintaining the
| sails. My understanding was that it isn't yet clear that this
| is the case, which is why they aren't deployed everywhere.
| jeffbee wrote:
| The first article I can remember reading about kites on cargo
| ships was in the Economist in 2005. These things have been
| around for a long time and have completely failed to have a
| meaningful impact.
| rozab wrote:
| >The white sailboat outside of Michelin Group's Swiss office
| doesn't have a sail at all. Instead, it has a wing.
|
| Ugh. A sail, most of the time, _is_ a wing.
| davinci26 wrote:
| I don't think it's a good idea.
|
| By adding so much surface area so high up you create a lever for
| winds to create torque to cape size the vessel.
|
| The way sailing boats circumvent this issue is by having a big
| long metallic fin at the bottom of the boat(called keel). The
| keel counteracts the torque of the wind when the boat rotates and
| brings it back to a steady position.
|
| The problem is that ports have fixed depth so if you modify an
| existing cargo ship with a keel it will no longer fit into the
| commercial ports
| nate_meurer wrote:
| I wonder how maintenance-intensive these things will be. Pin
| holes and tears will have to be patched by hand, and will require
| the material to be unfurled and checked for leaks inch-by-inch.
| mdeck_ wrote:
| Sure, the technology/design of these sails may be novel, but it
| feels a bit silly to be in awe of a new way to use sails to
| propel boats currently driven entirely by internal combustion
| engines. What will we think of next--a new way to use rivers to
| drive mills?
| HPsquared wrote:
| I have a novel idea for green vehicle propulsion using hay-
| powered biological machines.
| enjeyw wrote:
| Too late for that; the hay-powered biological machine has
| bolted.
| darksaints wrote:
| I think the recent innovations in sail technology on commercial
| ships have less to do with the fact that they use the wind, and
| more to do with the fact that they're now more reliable and
| easier to operate. Using traditional sails might have saved
| just as much fuel, but would have required a large crew always
| on call to operate the sails. For large cargo ships, you'd
| probably have to double the crew size, which is extremely
| expensive. Now the deck officers can control the sails and
| almost everything can be automated.
| ItalianPizza64 wrote:
| I had the opposite feeling: how had nobody yet thought of
| utilizing sails to improve fuel efficiency for these huge cargo
| ships?
|
| I don't know much of ships and their fuel consumption, but I
| would guess that any percentage point of fuel saving would
| quickly add up to a significant cost reduction
| detaro wrote:
| The idea and proposals have been around for decades.
| tawm wrote:
| Usually the ship's owners are not the ones paying for the
| fuel, that's on the charterer's account.
| Black101 wrote:
| We are going high tech...
| FridayoLeary wrote:
| Using wind to propel a ship? That's a very radical idea. I wonder
| why no one has thought of that before...
| Tepix wrote:
| Why do we let the top 50 or so biggest cargo ships get away with
| the enormous amount of pollution they generate? A few nations
| should get together and ban these boats until they switch to less
| polluting fuel.
| lcnmrn wrote:
| Why not build a container with battery inside and solar cells on
| top? Deploy at the top of the cargo ship. Equip the cargo ship
| with an electric motor.
| Ensorceled wrote:
| For the same reason a Tesla isn't covered in solar cells ...
| you need a lot of solar surface to move a cargo ship, a lot
| more than its surface area.
| fennecfoxen wrote:
| Also, the solar cells are relatively fragile, and you might
| reasonably expect serious damage in normal transit.
| kumarvvr wrote:
| Energy density of solar power and battery setups is nowhere
| close to that of oil based ones.
|
| Also, as oil is consumed, the ship gets lighter and easier to
| push. Not so with batteries.
|
| Making it more efficient is the only way forward.
| elihu wrote:
| The usual reason why not is that solar doesn't provide enough
| power, and batteries sufficient to power a container ship
| across an ocean would need to be impractically large.
|
| I wonder if maybe there are good options for powering electric
| ships mid-journey. For instance, suppose you have a container
| ship with enough battery capacity to operate for one day. On
| its usual route, there is a power line running along the ocean
| floor, and buoys at regular intervals with cables that bring
| the power up to the surface. Once a day, the ship stops at one
| of these buoys and charges its batteries for an hour, then
| continues on its way.
| barney54 wrote:
| Because cargo ships use massive amounts of energy and a little
| bit of solar power would do essentially nothing.
| [deleted]
| msandford wrote:
| While you're correct you haven't helped the OP learn
| anything. The idea is pointed in the right direction but the
| magnitude of the gain in efficiency doesn't add up to being
| significant. In order to know this you have to do the math.
|
| Large ship engines can be on the order of 10,000-30,000 hp or
| more. In KW that's 7.5-22MW.
|
| A large cargo ship might be Panamax
| (https://en.wikipedia.org/wiki/Panamax) and thus 950ft long
| and 105ft wide or have a total top surface area of 99750
| sqft. Commercially available solar panels have an efficiency
| of around 20% and sunlight is often quoted as 100w/sqft so
| you might be able to generate 2MW of electricity from
| covering the entire top of the ship in solar panels. 2MW
| compared with say 15MW is significant but there are problems.
|
| That's for a flat array, not something that tilts. So you're
| only going to get about 6hrs of full power output per day,
| assuming good weather. Now your 2MW drops to only 500kW of
| average power or lower.
|
| And those panels are going to cost at least $0.50/watt or
| something like a million dollars, nevermind mounting,
| inverters, cabling, etc. Could easily triple the price there.
| Plus the sea is rough on everything. If the panels are rated
| for 30 years on land you should expect to get less than 10
| years at sea, maybe less.
|
| Finally the assumption that you can simply cover the top of a
| ship with no repercussions isn't necessarily true. For
| tankers and bulk carriers you might get away with it. But on
| container ships you'd have to figure out how to make the
| entire array fold away since these ships are top loaded and
| unloaded. https://thumbs.dreamstime.com/z/container-cargo-
| cranes-unloa...
|
| The idea makes sense if you don't know the magnitudes of
| things. But once you do it starts to look less practical.
| ratsforhorses wrote:
| Thank you for that explanation, just a thought has there
| been any experiments with using the energy of the waves to
| help save energy? I remember a TED talk, a decade ago a
| about a flexible sailing boat...cant seem to find the link
|
| and then there is this https://en.m.wikipedia.org/wiki/Blac
| kbird_(land_yacht)#:~:te...
|
| Also I know there were some experiments with electrostatic
| or bubbles on the hulls of these huge ships...
| https://www.google.com/amp/s/www.marineinsight.com/green-
| shi...
|
| Also what about huge autonomous kites...?
| https://en.m.wikipedia.org/wiki/SkySails I mean surely such
| systems are complicated but with today's sensors and
| autonomous systems i'm sure people could come up with
| something that is better than burning 3rd grade fuel to
| bring us gadgets and junkets...
| spodek wrote:
| Let's remember that the greatest efficiency comes in not shipping
| so much stuff. We ship a lot of junk. Buying less stuff would
| lower emissions with no costs. On the contrary, we'd improve our
| lives.
| f6v wrote:
| What is considered junk exactly? I mostly buy groceries and
| toiletries.
| shadilay wrote:
| Groceries and toiletries are rarely shipped by sea. I'd
| define junk as something disposable that isn't consumed.
| Really anything by harbor freight that breaks easily.
| sosborn wrote:
| > Groceries and toiletries are rarely shipped by sea.
|
| You'd be surprised.
| barbegal wrote:
| The headline is misleading they haven't put anything on a cargo
| ship yet and likely never will. They have a single prototype
| yacht which can be seen in this image
| https://cdn.trendhunterstatic.com/phpthumbnails/454/454358/4...
|
| It's an interesting concept but I can't really see how it scales
| to large ships. To propel a larger ship you need a huge amount of
| force which requires a very sturdy mast and stays (guys) which
| support the mast. Without those elements the amount of force that
| can be transmitted will be negligible.
| hownottowrite wrote:
| The article says there are 15 in operation with 5 more coming
| in the next year. I couldn't find details on those ships but
| the MV Afros is a working cargo ship outfitted with wind
| assistive technology.
|
| https://www.nytimes.com/2021/06/24/magazine/cargo-ships-emis...
| barbegal wrote:
| The 15 in operation are not the puffy sails that the headline
| is talking about. They are a rotor design by a different
| manufacturer. The rotor style sails can save about 10 to 20%
| of a ship's fuel https://theicct.org/sites/default/files/publ
| ications/Rotors_...
| diydsp wrote:
| that's a great paper! I love that it walks the reader
| through the math! I wish more did that! I often feel papers
| I read are just a little outside my abilities, but this one
| actually makes a person smarter!
| pigeonhole123 wrote:
| I think most papers do this mostly to prevent too much
| scrutiny of their calculations. Publish or perish etc
| [deleted]
| briefcomment wrote:
| Found this awesome simple demonstration of Flettner
| rotors.[1]
|
| One question I have is, how would this work with a sort of
| semi-circle fan version, where the blades retract when they
| start getting pushed into the wind. This could
| theoretically have the rotor turn off of just wind power
| instead of external power. Here's a crude drawing lol [2].
|
| [1] https://www.youtube.com/watch?v=XsGin7CFaF8
|
| [2] http://draw.to/D47BxHT
| whatever1 wrote:
| Informative video on how it works [1]. Btw the 20% is an
| overly optimistic scenario.
|
| [1] https://youtu.be/JhAlWHSez90
| pentae wrote:
| > which requires a very sturdy mast and stays (guys) which
| support the mast.
|
| Did we read the same article? I read that the system was
| completely autonomous at the press of a button and
| automatically retracted in bad weather and for bridges
| andrewflnr wrote:
| I think GP is asserting that that part of the article is
| bullshit as it regards larger craft.
| bagacrap wrote:
| "The company plans to test the technology on a commercial
| freighter in 2022."
| kitd wrote:
| I don't think the aim is to replace motor power completely, but
| to offload some of the effort for long distances to reduce fuel
| consumption.
|
| As regard stays, the stay needs to be at 90deg to the sail
| orientation. Presumably mounted on some kind of circular track
| to rotate with the sail.
|
| The engineering is challenging but not inconceivable.
| agumonkey wrote:
| the safety side of things is also interesting, it provides a
| secondary moving force in case something happens with the ICE
| part
| ksec wrote:
| Even the rendering image in the article is on a _oil tanker_ ,
| not _cargo ship_.
| HeyLaughingBoy wrote:
| Oil is simply liquid cargo.
| darksaints wrote:
| Tankers _are_ cargo ships.
| callesgg wrote:
| It is clearly a bulk carrier as it ha large visible hatches,
| hatches used to reach the bulk cargo.
| 1337shadow wrote:
| https://en.wikipedia.org/wiki/Oceanbird
| Milkman128 wrote:
| Agree on the potential scaling issues but the article suggests
| it operates different from a normal sail
|
| more of how an airplane wing generates lift (bernoulli's
| principle) then catching wind.
| xyzzyz wrote:
| Normal sails also generate lift, which constitutes most of
| the thrust. Without it, it would be impossible to sail up
| wind.
| blabitty wrote:
| I'm just learning sailing but I believe traditional sails act
| like wings/airfoils as well, at least for part of the thrust.
| SergeAx wrote:
| This demand is significantly lower for rotating mast. On fixed
| mast we need shrouds to compensate side force. We also need
| deep massive fin to compensate overturning moment.
|
| Look at Maltese Falcon rotating mast. They don't have any
| shrouds, although they are carbon fiber made.
| darksaints wrote:
| What makes you think they haven't accounted for the mast
| engineering requirements?
| EMM_386 wrote:
| This seems so obvious I can't believe it hasn't been invented
| already. There must be reasons why.
|
| The only questions I would have are:
|
| - Do the sails automatically retract for height clearance?
|
| - What is the cost of installation (how many years to repay
| initial costs)
|
| - What are the ongoing maintenance costs?
|
| - Is the 20% the average cost savings per trip, or only while the
| sails are in use?
|
| Outside of that, this seems like an obvious solution for retro-
| fitting any tanker-type vessel. Cargo container ships may not be
| able to fit something like this.
|
| Still, 20% savings and that is regardless of the fuel used I'd
| imagine. It's just on top of whatever normally is powering the
| ship in conditions that would support the automatic deployment of
| the sails. I'd imagine this is best on certain routes that
| generally have stronger winds.
| bayindirh wrote:
| > Do the sails automatically retract for height clearance?
|
| It seems that system automatically deflates and tucks itself
| away for bridges or if sea becomes rough.
| rmah wrote:
| It was invented around 150 years ago. During the early age of
| steam, when engines were much less efficient than today and re-
| coaling/re-fueling infrastructure much less widespread, sail +
| engine arrangements were common.
|
| My understanding is that cargo ships usually operate on rather
| thin margins except during a occasional fat times (like right
| now)... If new sail designs were actually economically
| beneficial, ship owners would adopt them ASAP. As the quip
| goes, they like money. Color me cynical, but I don't really
| think they care too much about the environment.
| bitwize wrote:
| They even look like Bibendum himself!
| williesleg wrote:
| They still belch exhaust onto the ocean
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