# Rhumb Instruments: Boat Speed — GPS knotmeter for sailing > GPS knotmeter for sailing (iPhone/iPad app by Yes Please Boats Ltd.) - Source: https://appshunter.io/ios/app/rhumb-instruments-boat-speed/id6795911326 (this page in markdown: same URL + `.md`) - Developer: [Yes Please Boats Ltd](https://appshunter.io/developer/1696142148) - Category: Navigation - Price: $4.99 - Age rating: 4+ - Requires: iOS 17.0 · 2 MB - Languages: American English - Released: 2026-08-13 - Data updated: 2026-09-14 - User reviews in markdown: https://appshunter.io/ios/app/rhumb-instruments-boat-speed/id6795911326/reviews.md ## What is Rhumb Instruments? 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. ## Version history (last 2 releases) ### 1.1 — 2026-08-29 Apple Watch: Rhumb Instruments now has a watch app. It shows COG, SOG and the average SOG over the last 1 minute, 10 minutes and 1 hour, relayed from your iPhone, and uses the watch's own GPS when the phone is out of reach. A complication on the watch face opens it in one tap. Settings has a new Apple Watch section that shows whether the watch app is installed. COG and SOG no longer drift while the boat is moored. Background GPS keeps running through long stops at anchor, so the average SOG stays complete. The average SOG row shows a countdown while it is still warming up. The settings button follows the face colours, including red at night. Larger layout on iPad. Website, privacy policy and support pages open inside the app, and Rhumb, the sea chart app, is linked from Settings. ### 1.0 — 2026-08-13 No release notes. ## More apps by Yes Please Boats Ltd - [Brollr for BlackBox Global](https://appshunter.io/ios/app/brollr-for-blackbox-global/id6760652159) - [Rhumb: Sea Charts & Navigation](https://appshunter.io/ios/app/rhumb-sea-charts-and-navigation/id6788793992) All apps by Yes Please Boats Ltd: https://appshunter.io/developer/1696142148 --- *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 2026-09-14.*