Wing Sails on modern ships

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sophiecentaur said:
That's what I learned in my first hour of sailing and it works in ideal conditions. A craft of the size and cost that is described in this thread won't react fast - you can't just let the mainsheet fly when a sudden squall turns up (except in a small dinghy and I never used them much). With a container ship you already have a scary amount of windage which it there all the time and will have the full force from any beam wind.
I think you're sort of over-working the sailing analogy. This isn't a sailboat, subject to the whims of the seas. It's a fully-functional container ship, under power, with very sophisticated radar, that just happens to have an additional passive propulsion source whose sole function is to reduce fuel consumption.

You deploy the sail when conditions are right. You are still under power, just getting an assist. Unpredictable winds are dealt with by "luffing" the sails as-needed. No squalls are going to sneak up on you with your radar. Even if winds build precipitously, you're still not a sailboat, worrying about the whims of a rising gale - you're a container ship, under power, built for this. You simply depower the sails (first by "luffing" - which takes two seconds, and then by retracting) and continue steaming under full control.
 
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Cargill launched the sail-augmented bulk carrier Pyxis last August on a six-month test cruise saving on average 3 tons of fuel per day with only two sails. Is it worth it?

 
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In case you were wondering:
A Panamax bulk carrier (without sails) typically burns fuel at a rate of 90 Tons/day.
 
LNG tankers will not benefit directly from sail unless they are better insulated, since they are fuelled by the LNG that boils off during the voyage.

Australia sells coal and iron ore to China for steel making. It would be more sensible to make the steel next door to the coal mine in Australia, and so not ship most of the raw material in bulk carriers. Sail-assist will further lock-in that inefficiency.
 
Baluncore said:
LNG tankers will not benefit directly from sail unless they are better insulated, since they are fuelled by the LNG that boils off during the voyage.
I don't follow your logic.

Oh, you mean because their fuel is a waste product anyway, so there's no savings to be made off "free"?
 
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DaveC426913 said:
I don't follow your logic.

Oh, you mean because their fuel is a waste product anyway, so there's no savings to be made off "free"?
That’s how I interpreted it. Using the boil-off as fuel makes a lot of sense.
 
Yeah. Unless they’re willing to add a plant to return the boiloff to a liquid state, or add active refrigeration to the tanks, improving the fuel economy of an LNG tanker is kinda pointless. It’s just not economically sound.