# Would ships be more fuel-efficent if they had...hmm..tyres? **URL:** \ **Category:** Factual Questions\ **Created:** [August 7, 2017, 5:05pm UTC](https://boards.straightdope.com/t/would-ships-be-more-fuel-efficent-if-they-had-hmm-tyres/793016 "2017-08-07T17:05:05Z")\ **Posts on this page:** 6\ **Page:** 2
**Author:** ![Snnipe\_70E](https://avatars.discourse-cdn.com/v4/letter/s/b5a626/32.png) [@Snnipe\_70E](https://boards.straightdope.com/u/Snnipe_70E)\ **Post date:** [August 8, 2017, 12:49am UTC](https://boards.straightdope.com/t/would-ships-be-more-fuel-efficent-if-they-had-hmm-tyres/793016/21 "2017-08-08T00:49:25Z")
If there was anything to make ship engines more efficient it would be already be done,. The battle between steam and diesel engines was the battle of efficiency. Diesel engines are so far out in front of that steam ships are no longer being made. Except Nukes. ---
**Author:** ![Sage\_Rat](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/sage_rat/32/399_2.png) [@Sage\_Rat](https://boards.straightdope.com/u/Sage_Rat)\ **Post date:** [August 8, 2017, 1:18am UTC](https://boards.straightdope.com/t/would-ships-be-more-fuel-efficent-if-they-had-hmm-tyres/793016/22 "2017-08-08T01:18:13Z")
> [@Corry\_El](#): > > A bunch of spinning devices covering the whole wetted surface of the ship doesn’t sound too practical at first thought though. The best I can envision would be to have sheets of some material stretched along the underside o the hull, loop over the bow and stern on a rotating cylinder, and duck under the interior body of the ship, where some motor would cause them to move. It’s effectively the same technology as one of those moving walkways they have in airports. Given muck, seaweed, twigs, barnacles, etc. I’d expect the half-life for one of the bands to be about 12 hours before jamming the first time, even in the open ocean, and tearing completely within 2 weeks. ---
**Author:** ![busterpickle](https://avatars.discourse-cdn.com/v4/letter/b/258eb7/32.png) [@busterpickle](https://boards.straightdope.com/u/busterpickle)\ **Post date:** [August 8, 2017, 3:06pm UTC](https://boards.straightdope.com/t/would-ships-be-more-fuel-efficent-if-they-had-hmm-tyres/793016/23 "2017-08-08T15:06:37Z")
Maintenance on this idea would be insane. ---
**Author:** ![CalMeacham](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/calmeacham/32/35_2.png) [@CalMeacham](https://boards.straightdope.com/u/CalMeacham)\ **Post date:** [August 8, 2017, 3:11pm UTC](https://boards.straightdope.com/t/would-ships-be-more-fuel-efficent-if-they-had-hmm-tyres/793016/24 "2017-08-08T15:11:46Z")
> [@komolono](#): > > Ok, the obvious answer is - well, I don’t know. You tell me > [@](#): > > Let’s assume that tyres could be something like revolving sides of the ship, or anything revolving that’s in contact with water. How about if you stuck the tyres on the upper deck (not in contact with the water) and spun them really fast? > **[Rotor ship](https://en.wikipedia.org/wiki/Rotor_ship)** > > A rotor ship is a type of ship designed to use the Magnus effect for propulsion. The ship is propelled, at least in part, by large powered vertical rotors, sometimes known as rotor sails. German engineer Anton Flettner was the first to build a ship that attempted to tap this force for propulsion, and ships using his type of rotor are sometimes known as Flettner ships. > The Magnus effect is a force acting on a spinning body in a moving airstream, which produces a force perpendicular to both the di... > [@](#): > > A rotor ship is a type of ship designed to use the Magnus effect for propulsion. The ship is propelled, at least in part, by large vertical rotors, sometimes known as rotor sails. German engineer Anton Flettner was the first to build a ship which attempted to tap this force for propulsion, and the ships are sometimes known as a Flettner ship. > > The Magnus effect is a force acting on a spinning body in a moving airstream, which produces a force perpendicular to the direction of the airstream. This is used in backspin to increase range in ball sports, and also the bouncing bombs developed by Barnes Wallis.[1] Rotor ships take advantage of this same effect by spinning a large vertical cylinder, typically using an electric motor, and using the resulting force for propulsion. Due to the arrangement of forces, rotor ships are able to sail closer to the wind, which has a number of advantages. ---
**Author:** ![CalMeacham](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/calmeacham/32/35_2.png) [@CalMeacham](https://boards.straightdope.com/u/CalMeacham)\ **Post date:** [August 8, 2017, 3:15pm UTC](https://boards.straightdope.com/t/would-ships-be-more-fuel-efficent-if-they-had-hmm-tyres/793016/25 "2017-08-08T15:15:22Z")
here’s another use, in which such _Flettner Rotors_ ARE in contact with the water: > [@](#): > > Stabilizers > > A Flettner rotor mounted beneath the waterline of a ship’s hull and emerging laterally will act to stabilize the ship in heavy seas. By controlling the direction and speed of rotation, strong lift or downforce can be generated. The largest deployment of the system to date is in the motor yacht Eclipse > **[Flettner rotor](https://en.wikipedia.org/wiki/Flettner_rotor)** > > A Flettner rotor is a smooth cylinder with disc end plates which is spun along its long axis and, as air passes at right angles across it, the Magnus effect causes an aerodynamic force to be generated in the direction perpendicular to both the long axis and the direction of airflow. The rotor sail is named after the German aviation engineer and inventor Anton Flettner, who started developing the rotor sail in the 1920s. > In a rotor ship, the rotors stand vertically and lift is generated at righ... ---
**Author:** ![Folly](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/folly/32/3219_2.png) [@Folly](https://boards.straightdope.com/u/Folly)\ **Post date:** [August 8, 2017, 3:21pm UTC](https://boards.straightdope.com/t/would-ships-be-more-fuel-efficent-if-they-had-hmm-tyres/793016/26 "2017-08-08T15:21:27Z")
> [@Doubticus](#): > > Probably not as terrifying as [https://www.youtube.com/watch?v=TYB7DYWI4G8](https://www.youtube.com/watch?v=TYB7DYWI4G8) > [@Machine\_Elf](#): > > It’s not as nuts as it sounds. People regularly have water-crossing contests, and there’s a world-record for longest distance covered on water by a snowmobile (212 km). [Lotsa videos here.](https://www.youtube.com/results?search_query=snowmobile+on+water) Note from [this particular video](https://www.youtube.com/watch?v=gikCpPc8zZ8) that you don’t even need much of a running start (about ten feet of beach sand), provided you’ve got plenty of power and traction. Fair enough, but all those videos look like they are in nice warm weather, not “get[ting] a running start on ice” and then presumably hoping to find a flat spot or ramp on the other side instead of an ice ledge. [Previous page](https://boards.straightdope.com/t/would-ships-be-more-fuel-efficent-if-they-had-hmm-tyres/793016.md?page=1)