Might be time to buy a sextant

[AntarcticPilot]

Yup, of course, but adapting the electronic end, to the optical functions wouldn't be 'too' difficult. Modding the 'swinging' arm with a weight to always be pointing vertically down, would negate the need for being able to sight the horizon: simply sight the upper arm on the sun, through the tinted glass, and job done, providing the swinging arm can be guaranteed to be vertical, wouldn't it?
Not trying to be contentious, but it seems a solution to me as a non-navigator, but as an electronics engineer.

Using a pendulum mechanism to get a horizontal (or vertical reference) on a boat doesn't work; the motion of the boat makes it (almost) impossible. If it's heavily damped, it responds to the movement of the boat rather than the vertical, if it's lightly damped the motion of the boat sets it swinging. That's why astrolabes were never practical navigational instruments; they depend on hanging from a suspension point to get a horizontal reference. Plumb lines were commonly used for shore-based observations, but they don't work on ships. Actually, it's the same reason that pendulum clocks don't work reliably on ships.

Of course, you could use the angle sensor to get a direct reading of the angle in conjunction with a sextant, but then you'd have to re-engineer a sextant to fit the angle sensor!

 

[lustyd]

#159, seems to be a case of trying to re-invent the wheel, by the time the required optical gubbins have been added you may as well buy a sextant.

As long as the sextant is approved by the brain trust, of course ?

 

[lustyd]

Of course, you could use the angle sensor to get a direct reading of the angle in conjunction with a sextant, but then you'd have to re-engineer a sextant to fit the angle sensor!

Technically speaking the current iPhone would be able to tell you the angle of any star to the horizon with its various sensors so actually probably no reason to buy the ruler thing, although it does look like a cool tool.

 

[srm]

I seem to remember a paper in the Hydrographic Journal back in the 70's about adapting a sextant with an electronic sensor. This was for survey work using two sextant observers and horizontal angles. The data would go to an early desk top computer (basically a glorified HP calculator) and drive a flat bed plotter. It did not catch on, probably because microwave ranging systems were being experimented with at the same time, and quickly took over from sextants for inshore work.

Thinking of oddities I came across a sextant with the usual horizon mirror and two index arms, (probably when I worked for Hunting Surveys) the idea being that one observer could take a pair of angles. I briefly tried using it, but decided that it would take a fair bit of practice to get competent.

 

[jamie N]

I'm very happy that my idea will work perfectly in determining my position, unfortunately only if I use it alongside in port!
A good example of a "little knowledge being dangerous".

 

[Buck Turgidson]

iPhone sextant apps are available but I haven't tried any.