are boat knots and plane knots the same unit

@eri yeah

@electrocutie oh thank god

i was kind of expecting them to be different for no reason

@eri @electrocutie boat north and plane north are different

@charlotte @electrocutie well there’s literally just two definitions of north, the magnet one and the rotation one. that’s not unreasonable

@eri @electrocutie funnily enough boats use geographical north while planes use magnetic north

perhaps it’s due to planes trying to avoid polar flights because they are more dangerous (vs for boats if the routes are available they are just the Fastest Way to get from one side of eurasia or america to the other

@charlotte @eri planes use magnetic north, so boats use rotational north?

That's surprising since a magnetic compass is a very reliable navigational aid

@charlotte @eri planes fly over the north pole all the time; Its not just not the great circle for too many flights

Planes use magnetic north because its a reliable navigational aid and is used to define runway numbers, so you can approach a runway straight and true

@charlotte @eri But boats have magnetic compasses. So is it that they define their north by the sun and stars, traditionally, and then use the compass with a local adjustment between fixes?

@electrocutie @eri they mainly use gps for navigation nowadays which doesn’t use magnetic north

@charlotte @eri but GPS can't give a bearing without motion

@charlotte @eri well, 2 point can on a big ship but BLEH nasty GPS jitter heading

@electrocutie @eri that is true but if you approach 90° north you approach the geographic north pole, it would be confusing if the heading of the ship pointed at somewhere else in that case

@charlotte @eri it doesn't have to be. Its just a question of charting

@electrocutie @eri yeah true, the main commercial flights over the north pole are due to other factors like closed/hostile air spaces

but iirc due to the shape of earth’s magnetic field it can cause issues with board electronics up there too? that’s at least what i have read about the subject and yeah a magnetic compass is less likely to just glitch out than a board computer is

@electrocutie @eri presumably it’s easier navigationally to use gps (or similar gnss systems) reference system charts since they don’t move around over time

matters less if you operate in lower latitudes but if you ever want to enter the arctic ocean for any reason it does matter

@charlotte @eri radiation enough to make computers unusable is also pretty deadly. There is an increase, yes, but random errors already need to be contended with. I'm not aware of any special considerations there

@electrocutie @eri then again i also have no idea what goes into charting the arctic routes. given that it depends on weather pattern and how the ice melts

@charlotte @eri I'm very airplane brained and GPS just isn't trustworthy. I get that it can be used in monitored ways and on a ship you can float for free

I think I'm just going to have to quietly dislike it :(