Everything Old is new again - Flettner Rotor Ship is launched

Discussion in 'Boat Design' started by rwatson, Sep 1, 2008.

  1. rwatson
    Joined: Aug 2007
    Posts: 6,163
    Likes: 495, Points: 83, Legacy Rep: 1749
    Location: Tasmania,Australia

    rwatson Senior Member

    Nah. If you do a bit of reading from this thread, you will find that not only do you get better performance, but the ease of control is far better than with sails.

    Even if you did have a complicated hydraulic system run by computers, the shear windage of masts and rigging, let alone the maintenance, is a real downer.

    If you take the silhouette of one of these spinning columns, you have to have sail area 7 times that to match the drive. Its all controlled with one switch for spin direction and rotor speed, with no need to furl, or trim for wind direction.

    This is the most effective, efficient way of harnessing the wind of commercial purposes there is.
     
  2. whitepointer23

    whitepointer23 Previous Member

    Fair enough. But why are there not more of them.
     
  3. kerosene
    Joined: Jul 2006
    Posts: 1,285
    Likes: 203, Points: 63, Legacy Rep: 358
    Location: finland

    kerosene Senior Member

    Well lets give it a little longer. I am sure the analysis of the route is big part of this.
     
  4. whitepointer23

    whitepointer23 Previous Member

    Hasn't the flettner been around for decades already. Don't get me wrong. I am all for alternative propulsion . I will take rw's advice and read the threads on the subject.
     
  5. rwatson
    Joined: Aug 2007
    Posts: 6,163
    Likes: 495, Points: 83, Legacy Rep: 1749
    Location: Tasmania,Australia

    rwatson Senior Member

    Purely economics.

    The design and implementation is expensive, so it needs to be offset against fuel savings. As Kerosene mentioned, the prevailing winds have a lot to do with it.

    Earlier on this thread there is some pages from an article about the "Tracker" converted by Lloyd Bergeson that give some typical costings in real life.
     
  6. Pericles
    Joined: Sep 2006
    Posts: 2,015
    Likes: 141, Points: 63, Legacy Rep: 1307
    Location: Heights of High Wycombe, not far from River Thames

    Pericles Senior Member

  7. johnhazel
    Joined: Jun 2008
    Posts: 250
    Likes: 5, Points: 18, Legacy Rep: 60
    Location: Michigan

    johnhazel Senior Member

    HISTORICAL NOTE: In the early 1920's the force from a rotating cylinder was used to power a sailing ship. The idea, proposed by Anton Flettner of Germany, was to replace the mast and cloth sails with a large cylinder rotated by an engine below deck. The idea worked, but the propulsion force generated was less than the motor would have generated if it had been connected to a standard marine propeller!

    https://www.grc.nasa.gov/www/K-12/airplane/cyl.html
     
  8. rwatson
    Joined: Aug 2007
    Posts: 6,163
    Likes: 495, Points: 83, Legacy Rep: 1749
    Location: Tasmania,Australia

    rwatson Senior Member

    THEM saying so doesnt make it so.

    Given that Anton Flettner was an expert in all things propeller, ( helicopters, ships, windmills) the chance of him making that kind of calculation errror with the help of leading mathematicians ( including Einstein) is really low.

    Given the number of expensive current prototypes under development, there are a lot of engineers who wouldnt agree with that statement either.

    Now, some facts
    "two cylinders (or rotors) about 15 metres (50 ft) high, and 3 metres (10 ft) in diameter, driven by an electric propulsion system of 50 hp (37 kW) power."
    https://en.wikipedia.org/wiki/Rotor_ship

    "A few months later, a second ship was built with 3 “Flettner-Rotors”. This time, it was a 90-meter-long cargo ship called “Barbara”. It underwent trials in the Mediterranean by the navy of Weimar Germany, where it received positive reviews and operated without problems. According to the ship’s captain, the 3 Flettner-Rotors of the cargo vessel generated up to 600 hp of additional power and could be used 30-40% of the time during their journeys. Considering that the ship’s conventional engine had 1,100 hp, that’s a 54% boostt
    !"

    http://cleantechnica.com/2012/04/10/e-ship-1-21st-century-sailing/

    So, unless 150 hp of motor electric motors through a conventional screw could produce 600 extra hp of thrust, the statement is patently ridiculous.
     
  9. rwatson
    Joined: Aug 2007
    Posts: 6,163
    Likes: 495, Points: 83, Legacy Rep: 1749
    Location: Tasmania,Australia

    rwatson Senior Member

    Trials succcessfull

    "JUNE 1, 2015 — Finland's Norsepower Oy Ltd. and Bore Ltd have completed successful sea trials of Norsepower's Rotor Sail Solution wind propulsion technology on the 9,700 DWT Ro-Ro carrier MS Estraden. The trials confirmed fuel savings of 2.6% using a single small Rotor Sail on a route in the North Sea."

    "We are proud to be the first shipowner to install the Norsepower Rotor Sail, and demonstrate that wind propulsion technology has verifiable 5% fuel savings on a yearly basis, can be retrofitted without any off-hire costs, and is extremely easy to use in practice. It's our goal to find ways to establish sustainable shipping with minimal impact on our environment," said Jörgen Mansnerus, Vice President, Bore.

    http://www.marinelog.com/index.php?...ls-confirm-rotor-sail-fuel-savings&Itemid=231
     

    Attached Files:

  10. rwatson
    Joined: Aug 2007
    Posts: 6,163
    Likes: 495, Points: 83, Legacy Rep: 1749
    Location: Tasmania,Australia

    rwatson Senior Member

    Attached Files:

  11. johnhazel
    Joined: Jun 2008
    Posts: 250
    Likes: 5, Points: 18, Legacy Rep: 60
    Location: Michigan

    johnhazel Senior Member

    This is an example of "cherry picking" data. They show a 1/3 fuel savings with 16.7 Knt ship speed and 24knt at 135 degrees true wind. This combination of ultra fortunate wind speed and direction can only rarely be expected.

    On the next page of the advertisement you took the graph from, they claim a 2.1% net fuel savings for the full voyage. What is your estimate for the lost cargo space and extra weight plus additional fuel used with a head wind vs a ship without those big draggy sticks.

    Clearly, the weight and bulk of the rotors mounting and drive system would reduce cargo capacity by 1% each. So, lose 4% of your cargo to gain 2.1% in fuel efficiency. Just by the reduction in carry capacity you are already a loser.

    But wait there's more. The 2.1% was comparing a powered rotor ship to it's self with the unpowered rotors still attached. Since we are allowed cherry picking data here, lets take the case of 16.7 knots into a 24knt headwind. The coeficient of drag on a cylinder is about 0.5 the dynamic pressure is 1/2*1.2*20.9^2=263N/m^2. Drag is then 0.5 * 263N/m^2 * 432m^2 = 57kN. The ship then needs to provide 57kN*8.6m/s = 48kW to push the rotors through the air. So you can expect a big penalty on the effective gain when you compare a rotor vs non-rotor ship instead of the rotors-spining vs rotors-stationary that is used in the calculations of their propaganda. Recall that the penalty will be increased by the apparent wind vs true wind effect of rotating all winds to be more of a head wind.

    So by the data provided from those who have publicity stunts and gear to sell. They have shown the energy and economic benefit of Flettner rotors is nil.
     
  12. Leo Lazauskas
    Joined: Jan 2002
    Posts: 2,696
    Likes: 155, Points: 63, Legacy Rep: 2229
    Location: Adelaide, South Australia

    Leo Lazauskas Senior Member

    I agree there's something not quite right with it, John. My first thought was
    whether it get through a stringent, objective peer review. It reads too much
    like a self-assessment at the moment.
     
  13. rwatson
    Joined: Aug 2007
    Posts: 6,163
    Likes: 495, Points: 83, Legacy Rep: 1749
    Location: Tasmania,Australia

    rwatson Senior Member

    I agree with those sentiments totally. The data published by "vendors" is neither thorough, nor comprehensive, and definitely not peer reviewed.

    Trying to arrive at a definitive solution by these published figures is not possible which is why JohnHazels thorough analysis is no more reliable at arriving at a NIL answer than the publishers claimed x%.

    It will probably appear in the future that substantial savings are quite dependent on the skill of ships master to pick and steer courses favorable to destinations, like the clipper ships of old, BUT ALSO like the captains of current day long distance Jets who get bonuses if they select altitudes that utilize favorable upper atmosphere jet streams to save thousands of dollars in fuel per trip.

    The only reliable indicator to an answer, is to "follow the money", and if say a dozen engineers have wheedled millions of dollars out of the boardrooms of a few ship owners, then there must be "something" in it.

    The claims of insufficient derived power returns and unreliability are best answered by the existence of calculations substantial enough to get these experiments done and PAID for.

    Like all technology, the initial versions make big mistakes, are prone to excessive optimism, and are probably nothing like the final effective solution. BUT as far as wind powered fuel scavenging methods go - this seems to be one of the few methods actually having research funds spent on it.

    The answer, my friends is Blowing in the Winds ......
     
  14. rwatson
    Joined: Aug 2007
    Posts: 6,163
    Likes: 495, Points: 83, Legacy Rep: 1749
    Location: Tasmania,Australia

    rwatson Senior Member

    Bear in mind, :
    "2.6% using a single small TEST Rotor Sail on a route in the North Sea."

    Zero lost cargo space, as its on an unused stern quarter.

    Um, compare the little 'draggy stick' that is a uniform cylinder with the huge volume of superstructure with thousands of protruding eddy-makers. Just look at the exhaust stack alone !
     

    Attached Files:


  15. 1J1
    Joined: Sep 2012
    Posts: 111
    Likes: 15, Points: 18, Legacy Rep: 10
    Location: .

    1J1 Senior Member

Loading...
Forum posts represent the experience, opinion, and view of individual users. Boat Design Net does not necessarily endorse nor share the view of each individual post.
When making potentially dangerous or financial decisions, always employ and consult appropriate professionals. Your circumstances or experience may be different.