Rainbow’s Arc Positioning

What it does

One photo is the sight Sun and horizon together in the frame. The horizon is the level reference, so the boat’s roll and your grip don’t matter — hold the phone any way that works.
The whole reduction, worked for you Dip, refraction, semidiameter, parallax — the same corrections a paper sight reduction works, shown line by line, against a built-in almanac good through 2050.
Marking you can mean Draggable handles with a magnifier loupe, then one-pixel nudge arrows — because on a sun sight, a pixel is roughly a nautical mile.
A real deck log Start from a known position, log course-and-speed legs, tap Stopped whenever she isn’t moving. Every sight reduces against the DR for its own moment; every fix can restart the reckoning.
Fixes that own their error Cross any two sights into a running fix with a stated radius — and see the gap between where the log said you’d be and where the sky says you are. That gap is the current talking.
Noon, predicted Local apparent noon computed for your longitude with a countdown. A sight near the meridian reads directly as latitude — the classic noon sight, kept classic.

A camera sight is typically good to a few nautical miles, and every result says exactly how sure it is. When a sight isn’t trustworthy — sun too low, camera angle too uncertain, a line falling absurdly far from your reckoning — the app says so in plain language instead of pretending. Every boat carries GPS these days; this is not a contingency plan for the day they all fail at once, though it would serve. It is a fun alternative to try — and if you own a sextant, a genuinely useful one. It is not a chartplotter, and it never claims to be.

Never look directly at the sun. Every sight can be taken with the screen doing the looking — the app is built around that rule, and so is the manual.

May you find a rainbow’s end and treasure found wherever you sail or set your anchor.

Rainbow’s Arc Positioning

What it does

More