Built by mariners, for mariners.
STEM Maritime Systems LLC builds CHIEFMATE, a complete offline-first bridge toolkit for everyone who takes the open ocean seriously, from licensed officers to bluewater cruisers and offshore crews.
Here's the contradiction that started all of this.
The maritime world is going paperless. NOAA has ended its traditional paper and raster nautical charts, and modern bridges now run fully electronic on two ECDIS units. One is the primary, and the other is the backup that used to be a drawer full of paper. Yet at the same time, the Coast Guard still requires us to learn celestial navigation and pass exams on it for our oceans licenses.
Think about what that actually means. On one hand, you do everything on the ECDIS. On the other, if it all fails and you're told to fall back on celestial, how? The paper charts are gone. Even if you shoot the bodies, work a sight reduction, and find your position on a universal plotting sheet, you've got nowhere to apply it. An ECDIS simply isn't built to be navigated that way.
And be honest about the human side of it. How many working mariners could actually run a full sight reduction today, from bodies they shot themselves, without help? Not many. Most would spend the better part of a day digging through half-remembered steps just to land a single fix that was already six hours and fifty miles old by the time they finished.
That's the gap CHIEFMATE fills. It breathes new life into a skill the industry kept on the books but quietly walked away from. And even if you don't strictly need the celestial tools, they're an outstanding way to learn, practice, and stay sharp.
But navigation is only the start.
CHIEFMATE pulls weather from the same ECMWF model the major weather apps run on, and gives it to you for a fraction of what the competition charges for the exact same data.
For smaller vessels that aren't required to carry a class-approved stability program, there's never been a middle ground. Today the choice is a homemade Excel spreadsheet or stability done by hand on one end, and an expensive class-approved system on the other, with nothing in between. CHIEFMATE is that in-between: a real stability tool without the class-approved price tag.
And logbooks. Online logbook subscriptions add up fast, and a physical logbook has to be stowed aboard, eating up space you don't have to spare. For about the price of a single paper logbook each month, CHIEFMATE gives you a dozen-plus modules, the tools mariners actually reach for, all in one place.
That's the whole idea: one rugged, offline-first system that closes the gaps the industry left open, at a price that respects the people doing the work.
CHIEFMATE is designed and built by founder Kevin Steimle, a U.S. Coast Guard licensed Master (Oceans), Master of Towing Vessels (Oceans), and Chief Mate of Unlimited Tonnage, currently sailing as relief master aboard an anchor-handling tug supply vessel (AHTS) supporting offshore energy operations, and accruing sea time toward his Master Unlimited license.
Every module in CHIEFMATE (the sight reduction worksheet, the stability computer, the logbooks, the exam prep) was built by a working deck officer who stands the watch, runs the calculations, and carries the responsibility this software is designed to support. This isn't a tech company's idea of what mariners need. It's a mariner's answer to what the wheelhouse has been missing.
To give mariners back their independence, keeping the time-tested skills of the sea alive, instant, and usable when modern systems fail.
To build the complete offline-first maritime platform: navigation, charts, weather, stability, and vessel knowledge in one connected system that works anywhere on earth, with or without a signal. Built by working mariners, for working mariners.
A CHIEFMATE on every bridge: the trusted independent backup for working fleets worldwide, so that no mariner is ever lost when the signal ends.
Use it in your browser today, or install the desktop app for Mac and Windows, where your own computer becomes the server for the full offline experience. A dedicated rugged hardware unit and a mobile app for your phone or tablet are on the way. One account works across all of them.
CHIEFMATE is built and operated by STEM Maritime Systems LLC. If you'd like to read further about our company policies, they're all here: