[dreamcompiler]

Was this a big problem before computers? I doubt it. Back in the analog days two people would engage in a dialogue and ensure the units were agreed upon. Now people just blindly type data into a screen, or two computers blindly exchange packets without proper metadata.

It's ironic that we have 1000x better navigational accuracy than a 19th century tallship captain but we're much more careless with the data than he would have been.

[thisrod]

I don't think it's carelessness, rather that 1000x more accurate navigation gives you a lot more things to care about. That 19th century captain measured the angle between the pole star and the local horizon with a sextant; the cartographers did it the same way, because that was the only thing you could do.

Today, we work with atomic clocks, and our instruments fabricate an angle between the z-axis and a 100th order spherical harmonic series that models the shape of the ocean surface. Every few years, we update the model to keep up with plate tectonics. (Not exactly, but you get the idea.) There are a lot more things to go wrong, and not everyone programs in sanity checks to prevent small corrections from causing large errors.

[dreamcompiler]

Fair point.

> That 19th century captain measured the angle between the pole star and the local horizon with a sextant;

Which immediately provided latitude. To get longitude, he did the same with just about any other star and correlated the angle to an accurate clock and carefully-prepared tables.

That "accurate clock" business was why longitude was such a difficult navigational problem for so long until John Harrison finally cracked it. (I know this is getting OT but I find it fascinating.)

https://en.m.wikipedia.org/wiki/John_Harrison