3119: Flettner Rotor

2025-07-23T23:27:45Z

2A00:7C80:0:39B:0:0:0:12:

{{comic
| number = 3119
| date = July 23, 2025
| title = Flettner Rotor
| image = flettner_rotor_2x.png
| imagesize = 385x359px
| noexpand = true
| titletext = "And in maritime news, the Coast Guard is on the scene today after an apparent collision between two lighthouses."
}}

==Explanation==
{{incomplete|This page was created by a spinning shaft. Don't remove this notice too soon.}}

Randall is pointing out that a {{w|Flettner rotor}} can make a boat look like a lighthouse — and, since lighthouses are immobile while sailboats are not,{{Citation needed}} this would make other boats give a boat with the above affixations the right of way, by the simple expedient of avoiding its general vicinity and the presumed subsurface navigational hazards.

A vertical-axis Flettner rotor is a smooth cylinder which is spun along its axis. As air passes across it from the side, an aerodynamic force is generated at a right-angle (i.e. forwards) to propel the boat in the desired direction. If a directional light were attached at the top, it too would spin, sending out periodic flashes of light just like a lighthouse. Or, as it appears to be in the comic, a fully working {{w|Lighthouse#Components|lantern house}} may be fixed to the top of the non-rotating core to the rotor, within which its light rotates at a more usual rate independent of that of the vertical rotor.

A vessel directly in the path of the moving boat would have to perhaps consider the possibility that they are drifting towards rocks, but how one ''at anchor'' (and not obviously dragging its moorings) could reconcile the conceptual movement, especially if GPS data gives no reason to believe it, is left unexplained.

The title text describes "an apparent collision between two lighthouses", which could refer to two Flettnerized boats colliding with each other because they were ''both'' assuming that everyone else will give them the right of way.

Alternatively, a single Flettnerized boat complacently collided with an actual lighthouse, having similarly dismissed it as another boat that should have been avoiding itself. Thus, tangentially alluding to the old {{w|Lighthouse and naval vessel urban legend|urban legend}} in which a naval vessel insists that another radio operator at sea diverts course to avoid a collision, demanding right of way by citing their military importance, only to be embarrassed when the other operator reveals they are not another sea vessel, but a lighthouse.

==Transcript==
[A panel showing Cueball standing on a decorated Flettner Rotor Sailboat]

Text beneath panel: Sailing tip: If you have a Flettner Rotor Sailboat, you can add some fake plastic rocks and a light to make other boats give you the right of way.

{{comic discussion}}<noinclude>

3119: Flettner Rotor

2025-07-23T23:26:19Z

2A00:7C80:0:39B:0:0:0:12:

{{comic
| number = 3119
| date = July 23, 2025
| title = Flettner Rotor
| image = flettner_rotor_2x.png
| imagesize = 385x359px
| noexpand = true
| titletext = "And in maritime news, the Coast Guard is on the scene today after an apparent collision between two lighthouses."
}}

==Explanation==
{{incomplete|This page was created by a spinning shaft. Don't remove this notice too soon.}}

Randall is pointing out that a {{w|Flettner rotor}} can make a boat look like a lighthouse — and, since lighthouses are immobile while sailboats are not,{{Citation needed}} this would make other boats give a boat with the above affixations the right of way, by the simple expedient of avoiding its general vicinity and the presumed subsurface navigational hazards.

A vertical-axis Flettner rotor is a smooth cylinder which is spun along its axis. As air passes across it from the side, an aerodynamic force is generated at a right-angle (i.e. forwards) to propel the boat in the desired direction. If a directional light were attached at the top, it too would spin, sending out periodic flashes of light just like a lighthouse. Or, as it appears to be in the comic, a fully working {{w|Lighthouse#Components|lantern house}} may be fixed to the top of the non-rotating core to the rotor, within which its light rotates at a more usual rate independent of that of the vertical rotor.

A vessel directly in the path of the moving boat would have to perhaps consider the possibility that they are drifting towards rocks, but how one ''at anchor'' (and not obviously dragging its moorings) could reconcile the conceptual movement, especially if GPS data gives no reason to believe it, is left unexplained.

The title text describes "an apparent collision between two lighthouses", which could refer to two Flettnerized boats colliding with each other because they were ''both'' assuming that everyone else will give them the right of way. It could also mean that a Flettnerized boat collided with a real lighthouse.

Alternatively, a single Flettnerized boat complacently collided with an actual lighthouse, having similarly dismissed it as another boat that should have been avoiding itself. Thus, tangentially alluding to the old {{w|Lighthouse and naval vessel urban legend|urban legend}} in which a naval vessel insists that another radio operator at sea diverts course to avoid a collision, demanding right of way by citing their military importance, only to be embarrassed when the other operator reveals they are not another sea vessel, but a lighthouse.

==Transcript==
[A panel showing Cueball standing on a decorated Flettner Rotor Sailboat]

Text beneath panel: Sailing tip: If you have a Flettner Rotor Sailboat, you can add some fake plastic rocks and a light to make other boats give you the right of way.

{{comic discussion}}<noinclude>

explain xkcd - User contributions [en]

3119: Flettner Rotor

3119: Flettner Rotor