Hull Speed
GPS speedometer in knots
Free · Designed for iPhone. Not verified for macOS.
A simple sailing speedometer. Big, accurate GPS speed in knots on iPhone and Apple Watch — with a live trend graph so you can see your trim changes pay off.
Hull Speed is a simple speedometer for sailors. It shows your speed over the water in knots — big, clear, and accurate — on your iPhone and Apple Watch, with nothing in the way.
Built for trimming sails: make a small adjustment, then watch the number and the live trend graph to see whether you just got faster.
FEATURES
• Accurate GPS speed in knots, updated every second, using the same Doppler method as dedicated marine instruments — no paddlewheel to foul or calibrate.
• A live speed graph on a steady, fixed scale, so a small gain from a trim change is easy to spot.
• Enter your boat's waterline length and Hull Speed draws your theoretical hull speed right on the graph — see at a glance how close you are to it.
• Apple Watch app with a Keep Awake mode that holds the screen on while you sail.
• Completely private — your location is used only to compute speed on your device, and is never stored, sent, or shared. No accounts, no ads, no tracking.
One number, done right.
The developer, Peter Zink, indicated that the app’s privacy practices may include handling of data as described below. For more information, see the developer’s privacy policy .
Data Not Collected
The developer does not collect any data from this app.
Accessibility
The developer has not yet indicated which accessibility features this app supports. Learn More
Information
- Seller
- Peter Zink
- Size
- 2.6 MB
- Category
- Navigation
- Compatibility
Requires iOS 16.6 or later.
- iPhone
Requires iOS 16.6 or later. - Mac
Requires macOS 13.5 or later and a Mac with Apple M1 chip or later. - Apple Vision
Requires visionOS 1.0 or later. - Apple Watch
Requires watchOS 11.6 or later.
- iPhone
- Languages
- English
- Age Rating
4+
- 4+
- Copyright
- © 2026 Metric Devices