Edit: I have just finished reading The Neverending Story and this reminds me of the last part where Bastian works in the picture mines until he finds the right picture.
Not to mention, India’s coastline is very much not straight on a local scale. You’re bound to find a place where it turns perpendicular to the journey close to the theoretical starting point anyway.
Yeah but, I’m talking about this particular case, not making a mathematical rule. You have to move away from the coast, and then cannot turn, so you have to head towards Africa. You can’t set off toward Australia. Although I hadn’t considered that you can just move the starting point. So, there’s that.
No, that’s not Earth’s great circle, you’ll be turning slightly. It only seems straight on most map projections because they want latitudes to be horizontal.
It would, however, seem like a straight line to whoever was on the boat, because they’d be traveling due west the whole time, and the course corrections they’d have to make to keep going west would look the same as course corrections needed to account for wind, ocean currents, etc.
I know but you need to be the right amount of pedantic. Too little and any sufficiently large curve seems straight, too much and you point out that there is no straight line on the surface of a sphere.