[Jedd]

> which are conveniently given in knots (so nautical miles per hour)).

Yes. We may be misunderstanding each other.

It's convenient to have nautical miles per hour if you're using a base unit of nautical miles, and your map grid is nautical miles based. This isn't a surprise at all.

Estimating wind, tides, drift, etc, would be equally as easy if everyone was working in kilometres, and your maps were showing grids based on multiples-of-kilometres, and all speeds were given in kilometres per hour. Again, wouldn't be a surprise.