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Maersk installed 100-foot-tall rotating sails on one of its tankers

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Re: Maersk installed 100-foot-tall rotating sails on one of its tankers

#171

Post by acrooks »

fasteddie wrote: post #126
mabbo wrote: post #103

Earlier quoted context omitted.

I've long imagined some fun possibilities for this. I picture a small-ish shipping ship, say something moving 20 or 30 containers only, fully autonomous (100% crewless) with sails and solar only powering it. Solar electric motors handling the near-land operations and "not enough wind" conditions, sails otherwise. If you had autonomous loading and unloading, you would have zero variable/operational cost. I am certain…

The reason autonomous/crewless isn't really feasible or worth investing in is that most container ships only have a crew of about a dozen, and they are generally from low-wage countries so that their salary costs are far out-weighted by the fuel.

Maybe a little bit picky, but the average size of a crew on a, say, 9000 TEU container ship is actually closer to two dozen. 20-24 most of the time.

The number can rise further with more complex cargo.

Re: Maersk installed 100-foot-tall rotating sails on one of its tankers

#172

Post by eanzenberg »

lostlogin wrote: post #161
eanzenberg wrote: post #123

Earlier quoted context omitted.

>> An interesting note, Flettner was considered so valuable to the Germans in WW2 that Heinrich Himmler, the head of the Gestapo saw to it that Flettner's Jewish wife was escorted to Sweden for her safety for the duration of the war. That's nice and all but he still helped the nazis with military research while many of his colleagues fled, Einstein included.

It’s hard to understand, as that’s more or less moving her so he doesn’t kill her.

Great for his fam, bad for the other 8M jews (my grandparents’ families included)

Re: Maersk installed 100-foot-tall rotating sails on one of its tankers

#173

Post by superkuh »

adrianN wrote: post #162
nattaylor wrote: post #153

Earlier quoted context omitted.

Some fleets have implemented special bottom paint to reduce drag by reducing algae growth.

I wonder how long a magnetic cleaning robot could survive on the hull of such a ship.

After manned narco subs and towed sub capsules were mitigated by new police efforts drug traffickers experimented with magnetically attached parasite containers on the side of large shipping boats. But they didn't have to move.

Re: Maersk installed 100-foot-tall rotating sails on one of its tankers

#174

Post by macmac »

DannyB2 wrote: post #80
macmac wrote: post #38

Earlier quoted context omitted.

That's Maersk Line, which is the container shipping division of Maersk. The rotor sails are being installed on a tanker vessel from Maersk Tankers. Deck space is a valuable commodity on a container vessel, so not as obvious where to place the rotors.

I quoted that line exactly from TFA. (the friendly article)

I am sure you did. That doesn't make it any less misleading.

Re: Maersk installed 100-foot-tall rotating sails on one of its tankers

#175

Post by cwmoore »

LeifCarrotson wrote: post #143
cwmoore wrote: post #44

Earlier quoted context omitted.

I believe you. The difference between required and available power is large. Can you provide sources that derive/explain/summarize the figures you present so that others may better understand the reasoning?

Sure, sorry. The rule-of-thumb max for solar irradiance is 1 kW/m^2 (noon, clear day, low latitude, etc): https://en.wikipedia.org/wiki/Solar_irradiance#Irradiance_on... The rule-of-thumb for the electric power output of a solar cell is about 20% of the irradiance. https://en.wikipedia.org/wiki/Solar_cell_efficiency And because this drops in the morning and evening and falls to zero at night, you realistically only g…

Thanks!

My acceptance of the idea that drag might be manageable has to do with volume displacement and not surface area.

A long shallow "tail" could exert orders of magnitude less drag (vis a vis surface area) than a deep heavy hull pushing up a big wake. (Related to why boats are long and narrow...)

https://en.wikipedia.org/wiki/Wave-making_resistance

Edit: The fact that you see that as a clear non-starter has me wading into Google results for hydrodynamics. It is definitely over my head, but I am curious. Is there a rule of thumb for drag in water that I'm not finding?

https://www.boatdesign.net/threads/wetted-surface-area-appro...

http://www.engr.mun.ca/~bveitch/courses/r-p/Assignments/ITTC...

http://www.fade.up.pt/cifi2d/files/effect-of-wetted-surface-...

Re: Maersk installed 100-foot-tall rotating sails on one of its tankers

#176

Post by cwmoore »

cwmoore wrote: post #94
harg wrote: post #89

Earlier quoted context omitted.

A typical 250W PV panel is 1.6m^2. 300m2 of these will give a peak power of about 47kW which is about 63hp. for comparison a Wärtsilä RTA96C is rated for over 80MW which means you'd need over 0.5million m^2 of PV panels to match this. (about 85 football pitches). Feasible but expensive

The idea that it would need to be 1000X bigger is helpful. The original poster's figure of 300m^2 does not make much sense.

Rereading with the principle of charity in mind, I think the original poster meant (300m)^2, though it was not clearly so.

Re: Maersk installed 100-foot-tall rotating sails on one of its tankers

#177

Post by flyinglizard »

mabbo wrote: post #103
jessewmc wrote: post #64

Earlier quoted context omitted.

Ignorant question: if operational costs trump all, especially fuel (Maersk says in the article 60% of operational cost) why not pure sail power? Is there some other maintenance cost or infeasability there? Or is there another hidden variable that is not satisfied?

I've long imagined some fun possibilities for this. I picture a small-ish shipping ship, say something moving 20 or 30 containers only, fully autonomous (100% crewless) with sails and solar only powering it. Solar electric motors handling the near-land operations and "not enough wind" conditions, sails otherwise. If you had autonomous loading and unloading, you would have zero variable/operational cost. I am certain…

Funny, I had this idea around my head for a while tagged under the "world changing startups I'd like to try someday" :)

I think it will do to shipping what two engine, midsized passenger jets (A350/787) are doing to air travel: connect directly between small ports anywhere, instead of using very large ports as hubs. FedEx/UPS could have sea terminals anywhere, possibly automated.

Global shipping will only grow and I don't see a driver for air freight prices to drop enough so that things are truly international (e.g. buy a fridge from AliExpress).

I think it needs to happen, and will happen.

Re: Maersk installed 100-foot-tall rotating sails on one of its tankers

#178

Post by ThrustVectoring »

jessewmc wrote: post #64
abtinf wrote: post #18

Some years ago I read The Box by Marc Levinson, a history of containerized shipping. Highly recommend it. If you live in SF and have wondered about the numerous barely used piers, this book explains their history as well - and why the major container terminal ended up in Oakland instead. One of the painful early lessons for the industry was the discovery that minimizing operational costs (particularly fuel and mainte…

Ignorant question: if operational costs trump all, especially fuel (Maersk says in the article 60% of operational cost) why not pure sail power? Is there some other maintenance cost or infeasability there? Or is there another hidden variable that is not satisfied?

Capital expenditures are also pretty important. If the ships cost twice as much to build, you're paying twice as much in interest (or more). At the same amount of investment, you're shipping fewer things more profitably, and that only really makes sense if you can get attractive debt terms under pretty intense price pressure.

Re: Maersk installed 100-foot-tall rotating sails on one of its tankers

#180

Post by tajen »

fasteddie wrote: post #126
mabbo wrote: post #103

Earlier quoted context omitted.

I've long imagined some fun possibilities for this. I picture a small-ish shipping ship, say something moving 20 or 30 containers only, fully autonomous (100% crewless) with sails and solar only powering it. Solar electric motors handling the near-land operations and "not enough wind" conditions, sails otherwise. If you had autonomous loading and unloading, you would have zero variable/operational cost. I am certain…

The reason autonomous/crewless isn't really feasible or worth investing in is that most container ships only have a crew of about a dozen, and they are generally from low-wage countries so that their salary costs are far out-weighted by the fuel.

> from low-wage countries

I was surprised we still made shipmates (?) in Canada and other western countries. BTW I learnt that from the youtuber JeffHK who makes both relaxing and informative videos about what it’s like to work in the commercial ship industry: https://youtu.be/tdMYEKwxTyo

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