# CHIEFMATE: Marine Navigation — Offline celestial navigation

> Offline celestial navigation (iPhone/iPad app by STEM Maritime Systems LLC.)

- Source: https://appshunter.io/ios/app/chiefmate-marine-navigation/id6796434327 (this page in markdown: same URL + `.md`)
- Developer: [STEM Maritime Systems LLC](https://appshunter.io/developer/6796434329)
- Category: Navigation, Reference
- Price: Free with in-app purchases
- Age rating: 4+
- Requires: iOS 15.0 · 3 MB
- Languages: American English
- Released: 2026-09-05
- Data updated: 2026-09-30
- User reviews in markdown: https://appshunter.io/ios/app/chiefmate-marine-navigation/id6796434327/reviews.md

## What is CHIEFMATE?

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.

## Pricing and in-app purchases

Base price: Free.

**Subscriptions**

| Subscription | Price | Period |
| --- | --- | --- |
| Master | $89.00 | per month |
| Watch Officer | $49.00 | per month |



## Version history (last 5 releases)

### 1.0.8 — 2026-09-28

Swipe from the left edge of the screen to go back a page, the way Safari does, instead of reaching for the Back button. No change to the navigation tools.

### 1.0.7 — 2026-09-25

Offline charts: your position now waits for a fix good to 50 meters instead of jumping to the first rough guess from a cell tower, and the chart header shows how good the fix is. The accuracy circle around your mark shows the same thing at a glance.

### 1.0.6 — 2026-09-24

Offline charts. While you have a link, download the NOAA charts for a voyage or for any area you frame on the chart. Then open them with no signal, see your own position on them, and take a bearing or a range with a tap. Charts are drawn sharper for phone screens. Long pages now scroll clear of the tab bar.

### 1.0.5 — 2026-09-16

The offline tools now sit clear of the notch and the home indicator on every iPhone. The app tells the platform it is the app, so sign in and the account pages open in the phone layout every time. No change to the navigation tools.

### 1.0.4 — 2026-09-10

The app now opens straight into your sign in, then lands on a home built for the phone: large rows for every tool and a tab bar for Home, Navigate, Log, Weather and More. Emergency procedures, celestial, tides, weather, the logbook and the record pages are laid out for a phone screen. The offline tools sit behind one link and take over by themselves when there is no signal. The launch screen shows the whole CHIEFMATE mark.

## Apps similar to CHIEFMATE

| App | Rating | Price | Category |
| --- | --- | --- | --- |
| [MSI MAP](https://appshunter.io/ios/app/msi-map/id6794602967) | — | Free | Navigation |
| [Seafarer Job Wizard](https://appshunter.io/ios/app/seafarer-job-wizard/id6794601860) | — | Free | Navigation |
| [TALAY: Marine](https://appshunter.io/ios/app/talay-marine/id6788123076) | — | Free | Navigation |
| [Wärtsilä BridgeMate](https://appshunter.io/ios/app/wartsila-bridgemate/id1174910904) | — | Free | Navigation |
| [Navigation Almanac](https://appshunter.io/ios/app/navigation-almanac/id6777455516) | 5.0 (2) | Free | Navigation |
| [Binnacle: Nautical Calculator](https://appshunter.io/ios/app/binnacle-nautical-calculator/id6523426668) | 5.0 (1) | Free | Navigation |

## Related topics

[marine navigation](https://appshunter.io/ios/topics/marine-navigation)

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*Data collected daily from the US App Store and indexed by [AppsHunter](https://appshunter.io/). User reviews are verbatim App Store reviews. Ratings, prices and chart positions refresh continuously; this snapshot is from 2026-09-30.*