Magnus effect for ship propulsion

Discussion in 'Propulsion' started by 1J1, Mar 6, 2017.

  1. Ilan Voyager
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    Ilan Voyager Senior Member

    It will transform the cargo ship in a vessel with such a drag that all benefits will be annihilated. The rudder will end failing.
    Nowadays ships are designed for propeller thrust and rudder.
    Add the the problem of the deck encumbered by the rotors, that does not help for charging and discharging (it's the major factor), and the fact that most of the time the rotors are an aerodynamic drag and an hazard in bad weather.
    That explains why almost nobody wants a magnus rotor as they are uselless as addition to an existing boat unless major retrofit.
    Kites are finally more interesting at least for the ships taking routes with a good wind from the stern, like in the trade winds.
    There are just a small mast on the bow and the winches which do not interfere with the operations in the harbor. Also no big structural problems to solve and won't break the rudder as the kite is in front of the ship going downwind, so the ensemble is autostable..
    They do not cause drag and are not a safety hazard. Little to maintain. The kites are used only when needed, and if there is a problem you let it fly away. Kites are less expensive and can be adapted to any ship.
    And I almost forgot a kite seeks the wind at 100 to 400 meters high, where it's blowing steadily without disturbances by the sea, but you have to be careful of the effects made by the clouds. Kites may work on ships on some routes.
     
  2. 1J1
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    1J1 Senior Member

    I think it's possible to design a cargo ship with retractable rotors (so they can be lowered during storm or cargo ops in port) while still keeping the cargo volume of an equal-sized ordinary ship. E-SHIP 1 is not ideal - you will need to have a clear berth or be very accurate to not hit the rotors with the crane during cargo ops, but as a specially designed rotor RoRo ship, I think it does its role for the owners alright. There are a couple of recent concepts of short-sea freighters with 2 & 4 rotors but in my view they aren't ideal either as rotors affect the arrangement, limiting the cargo volume & being an obstruction for shore cranes.

    How many freighters with kites build? I remember only like 2 of them built near the end of the 2000s, nothing more.
     
  3. Ilan Voyager
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    Ilan Voyager Senior Member

    Like I said in a former post, the very low prices of shipping since 2008 as there is over equipment. The sluggish global trade, and the bankruptcy of a major Korean company, added to political incertitudes about the States with the new president, do not push any shipping company to invest in new technologies with hypothetic results. Note also that also these new technologies add complexity and more maintenance. Nobody needs that for the while.

    A slight diminution of the speed gives immediate results without investment. After a new optimization is calculated. Clients look for cheap shipping, and one week more on Shangai-Rotterdam or other long range shippings does not bother them. So it's the actual trend.
    Note that the new boats are slower than those of the precedent generation.
    Cargo ships may be big but are always very simple. A boxy boat with one engine, one propeller and direct transmission. For maneuvering in harbors tugs are used. The SOR is very simple, the design straightforward, and the building cheap with very ordinary materials.
    So nobody will enter in the complexity of rotors on cargos or freighters, except for some subsidized boats. Kites are useful only on some downwind routes, and to be efficient kites must be of a respectable surface, probably not so easy to manage. Reliability and durability can be a problem as with rotors. Nobody wants reliability problems, and high cost maintenance.
    The new IMO standards about pollution will be a new challenge in 2019, but the companies will take the simplest and cheapest solutions, with minimal maintenance. A lot of people are working on the problem.
    Rotors are a very complex and expensive solution with no great results, kites are simpler but lot of unknowns remain and it's maybe useful only in some routes. So these solutions doesn't seem to have a great future, except in some very peculiar cases.
     
  4. TeddyDiver
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    TeddyDiver Gollywobbler

    With respect kites are allmost useless downwind. Reach from close to beam they shine..

    BR Teddy
     
  5. Ilan Voyager
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    Ilan Voyager Senior Member

    It's not kitesurfing. The kites are also different. On ships and small motorboats kites are used with the wind somewhere from the stern and only if the differential of speeds between wind and boat is sufficient.
    Leeway transforms a ship in a useless piece of drag, and nobody on a ship is fool enough to play with a big kite on the beam.
    So the kite is kept +25º-25º from downwind as I seen myself when making trials of kites (a personal pure beach kite 8 m2 and a borrowed kitesurfing one, which was almost impossible to use efficiently on a panga) on a 33 feet panga Eduardoño motorized by a 6.0L Mercruiser with a Bravo 3 in Dominican Republic on 2011.
    The purpose was to have an auxiliary "engine" in case of problem with the Mercuiser. An idea suggested to the owner. The speed obtained was 3-4 knots with my kite, a 8 m2.
    After seeing the struggle of the captain with the kites, useful only downwind in a narrow angle range on such a boat, the owner wisely decided to install a better VHF, buy a good cell phone, and a 50 HP 4S Suzuki outboard as auxiliary, and for the maneuvers in the marina were the outboard shined whatever the direction of the wind...
    For information on 7 March 2016, the company SkySails GmbH & Co. KG had to file for insolvency and was dissolved on 5 April 2016.
    It's a very academic discussion...
     
  6. TeddyDiver
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    TeddyDiver Gollywobbler

    And being downwind kites they are pretty useless IMHO. Computers are driving trucks on public roads nowadays so why not proper kites to get some real effiency.

    BR Teddy
     

  7. Ilan Voyager
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    Ilan Voyager Senior Member

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