CHIEFMATE: Marine Navigation

Celestial navigation that works with no signal. Sight reduction, sun and twilight, and noon latitude, right in your pocket. A backup for when GPS and comms fail.

CHIEFMATE is a professional maritime navigation companion built for mariners who need tools that keep working when everything else goes dark.

WORKS OFFLINE, NO SIGNAL NEEDED Even in airplane mode, far offshore, CHIEFMATE computes celestial navigation entirely on your device: • Sight reduction (intercept method) for the Sun, Moon, planets, and all 57 navigational stars. Enter your sextant altitude and get a line of position. • Sun & twilight: sunrise, sunset, meridian passage (LAN), civil and nautical twilight windows, day length, and sunrise amplitude. • Latitude at noon (LAN) and by Polaris. • STCW / MLC hours of rest compliance.

Positions are computed to arcminute accuracy, finer than a sextant resolves, using a built-in solar model and a bundled astronomical ephemeris. No internet, no subscription, no account required for the offline tools.

THE FULL PLATFORM WHEN YOU'RE CONNECTED Sign in with your CHIEFMATE account to open the complete platform: charts that work offline, weather routing, electronic logbooks, tides and currents, stability and loading, publications, emergency procedures, and an AI watch assistant.

BUILT BY MARINERS, FOR MARINERS CHIEFMATE is one connected workplace: a sight reduction flows into your logbook and plotting sheet automatically. It runs on a rugged shipboard computer, on the desktop, and now in your pocket.

Use CHIEFMATE alongside official publications, a paper almanac, and sound judgment. It supports your decisions. It does not replace prudent seamanship or required carriage equipment.

Terms of Use (EULA): https://www.apple.com/legal/internet-services/itunes/dev/stdeula/

CHIEFMATE is a product of STEM Maritime Systems LLC.