Rhumb Line Apps

Rhumb Line Apps LLC

Practical apps for
people on the water.

We build careful, offline-capable tools for boaters and mariners — grounded in real charts, tide data, and the way people actually cruise.

Meet ICW Planner → About the studio

Our apps

Focused, no-nonsense tools that work when you're offline and out of cell range — because that's where boaters need them most.

ICW Planner app icon

ICW Planner iOS

Plan a day on the Atlantic Intracoastal Waterway: bridge opening times, speed optimization, tides, currents, and clearances — Norfolk to Miami and the Keys gateway.

iPhone & iPad · iOS 17+ · Free with optional Pro
Learn more
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More on the way In the yard

We're a young studio with a full slip of ideas for cruisers. New apps will show up here as they launch.

What "rhumb line" means

A rhumb line is the navigator's steady course — a path that holds a constant bearing across every meridian. It isn't always the shortest line on the globe, but it's the one you can actually steer. That's our philosophy for software, too: dependable tools that hold their heading, do one job well, and keep working when the signal drops.

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Offline-first

Charts, schedules, and calculations live on your device. No cell tower required to plan your day.

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Grounded in real data

NOAA tides & currents, USCG notices, and official bridge regulations — sourced, dated, and versioned.

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Privacy by default

No accounts, no ads, no tracking. Your trips stay on your phone. See our privacy policy.