Rhumb Instruments: Boat Speed
GPS knotmeter for sailing
$4.99 · Designed for iPad. Not verified for macOS.
Pay once and it is yours. Big COG and SOG digits, steadied for the water, with average speed over 1 minute, 10 minutes, and 1 hour.
Rhumb Instruments turns your phone into the helm instrument most small boats are missing: course over ground (COG) and speed over ground (SOG) in digits big enough to read from the wheel, with your average speed underneath.
A phone's raw GPS numbers are jumpy on the water. Chop, tide, and the motion of a small boat make the bare readout flick around, and two phones held side by side will disagree. Rhumb Instruments steadies both values the way a real marine instrument does. SOG is a short rolling average and COG is smoothed over the last seconds of track, so the digits settle on what the boat is actually doing.
It works out of the box. Open the app and the instruments are live, in knots and degrees true (°T). You pay once and everything is included.
THE INSTRUMENTS
• COG and SOG fill the screen, sized for a glance from the helm in bright light
• Both values are steadied for the water: a rolling average for SOG, a smoothed track for COG
• The screen stays awake while the app is open
AVERAGE SPEED
• Trailing average SOG over 1 minute, 10 minutes, and 1 hour, computed on the device from GPS
• The 1 minute window shows how the boat is doing right now; the 1 hour window shows what you will really average on a passage
• Useful for passage timing, race legs, and checking a new prop or sail trim
SIMPLE ON PURPOSE
• One screen, ready when you open it, with nothing to configure
• Works worldwide from the phone's GPS, and your position stays on your device
• Auto appearance follows the sun: day, twilight, and a red night face
MADE FOR
Sailors and motorboaters at RYA Day Skipper level and below, racers timing their legs, and anyone in a dinghy, RIB, or kayak who wants a steady speed readout. It is a GPS knotmeter built for the water.
Rhumb Instruments is built by a Yachtmaster Offshore skipper, the maker of Rhumb, the sea chart app. It is a one-time purchase.
Rhumb Instruments is an aid for recreation. It does not replace official instruments or safe navigation practice.
Ratings & Reviews
- This app hasn’t received enough ratings or reviews to display an overview.
Average SOG is now a session. Tap Start averages to begin and Stop to end. The phone uses GPS in the background only while a session is running, and the Background GPS setting is gone.
Apple Watch shows the average SOG only while a session is running on the iPhone.
The developer, Yes Please Boats Ltd, 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
- Yes Please Boats Ltd
- Size
- 1.7 MB
- Category
- Navigation
- Compatibility
Requires iOS 17.0 or later.
- iPhone
Requires iOS 17.0 or later. - iPad
Requires iPadOS 17.0 or later. - Mac
Requires macOS 14.0 or later and a Mac with Apple M1 chip or later. - Apple Vision
Requires visionOS 1.0 or later. - Apple Watch
Requires watchOS 10.0 or later.
- iPhone
- Location
- This app may use your location even when it isn’t open, which can decrease device battery life.
- Languages
- English
- Age Rating
4+
- 4+
- Copyright
- © 2026 Yes Please Boats
