Wing Sails on modern ships

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Discussion Overview

The discussion centers on the potential implementation of wing sails, specifically the WISAMO design by Michelin, on modern cargo ships. Participants explore the implications for sustainability in maritime transport, the practicality of such sails on different types of vessels, and the engineering challenges associated with their use.

Discussion Character

  • Exploratory
  • Debate/contested
  • Technical explanation

Main Points Raised

  • Some participants highlight the WISAMO wing sail's potential to reduce carbon emissions by up to 20% for existing ships and 50% for new builds.
  • Concerns are raised about the practicality of using wing sails on container ships due to stability issues and the need for a clear deck.
  • Others argue that as long as the sails can clear the top containers, they could be feasible on container ships.
  • It is suggested that high-mounted sails could compromise vessel stability, necessitating new hull designs and ballast systems.
  • Participants express skepticism about the viability of wing sails on large container ships, citing operational limits and existing stability challenges.
  • Some discuss the engineering challenges of maintaining sail tension and the pressures involved in the design of inflatable sails.
  • There are references to a lack of large vessels currently using this technology, with only small demo vessels reported.
  • Discrepancies in reported pressures for the sails lead to further technical discussion about their implications for performance.
  • Some participants question the overall feasibility and potential for widespread adoption of wing sails in the shipping industry.

Areas of Agreement / Disagreement

Participants express a mix of skepticism and curiosity regarding the practicality of wing sails on different types of ships. There is no consensus on their feasibility for container ships, with some arguing for their potential and others highlighting significant challenges.

Contextual Notes

Participants note limitations in the current understanding of the technology, including missing information about operational pressures and the engineering challenges posed by larger vessels. The discussion reflects a range of perspectives on the viability of wing sails in maritime applications.

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  • #32
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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  • #33
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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  • #34
In case you were wondering:
A Panamax bulk carrier (without sails) typically burns fuel at a rate of 90 Tons/day.
 
  • #35
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.
 
  • #36
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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  • #37
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.
 
  • #39
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.