The natural Navigation: The Right Course, Naturally

In this photo, one of the Outward Bound Oman instructors, who I visited recently, is being taught how to use a traditional and beautifully simple navigational instrument called a ‘kamal’.

This instrument is as simple as they get: it works by forming a triangle. If you know the base of a triangle (the fixed length of twine from eye to instrument) and you know the height of the triangle (the number of fingers counted up from the horizon), then you have a fixed angle to the horizon. This is the ancestor of nearly all navigational instruments prior to electronics. (In fact the triangulation used has a lot in common with the way GPS works, but that is another story.)

How does it work in practice?

Here’s the simplest example: the Pole Star (Polaris, North Star) will be the same angle above your horizon as your latitude. At the North Pole…

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My thanks to William Goble for bringing my attention to a extraordinary piece of navigation history.

Although standard practice in aerial navigation at the time, it is now remarkable to consider that the most powerful weapon in the history of warfare was guided using the stars. The Enola Gay dropped its atomic bomb payload on Hiroshima after an 1800 mile flight where the aircraft’s position was checked using the stars. From the Guardian article:

‘Van Kirk’s role was navigator: “We did things the old-fashioned way: celestial navigation, telling your position by the stars. We had a dome up top of the plane to sit up in and shoot the stars with a bubble sextant.”

The full article can be read in the Guardian Online.

What a difference an hour makes, I took this photo only one hour later than yesterday’s. Venus was still visible to the naked eye, but being drowned out by the minute as the morning’s twilight becomes dawn itself. Twilight is a hugely important time for celestial navigators as it is the only time that both the stars and horizon are visible. Celestial navigation relies on using a sextant to measure the angle between stars and the horizon. Before the morning twilight the horizon is not visible and after it the stars have disappeared. In the evening it is of course the other way round.