From cast-off to logbook
Your voyage.
Automatically
logged.
Rubberduck records your GPS track, weather, wind, NMEA data and crew details fully automatically in the background — from casting off to tying up. Plan multi-leg voyages with cash box, watch schedule and packing list, and split costs fairly across the crew. Your area info is right on board: official notices to skippers, water levels, marine weather and tides at your position. At the end, publish your voyage with a single tap as your own logbook on Kielwasser — with a boat profile, live position and shareable voyage cards. No paperwork, not a single manual entry.
This is the cockpit view.
Everything you need on board.
Automatic logbook
GPS track with distance in nautical miles; log entries created automatically by time interval, distance sailed or course change — each individually configurable. Runs fully in the background, your iPhone can stay in your pocket.
Live NMEA data
Wind, depth, water temperature and more straight from your boat network (NMEA 0183 over WiFi) — logged automatically every 15 minutes.
Weather, sea state & tides
48-hour forecast with strong-wind warnings, wave height, high and low water — recorded automatically at passage start and updated underway.
Barometer & storm warning
Air pressure live from the NMEA network or iPhone sensor, with a 3-hour trend and graph. If pressure drops sharply, the app warns of a storm in good time — with banner, siren and a waking notification, even during anchor watch. Readings are logged automatically in the passage log.
Night watch & on-board alarm
Night-watch timer (dead-man): confirm at chosen intervals that you’re awake — the button changes position each time. The on-board alarm link makes anchor, storm and dead-man alarms ring on every iPhone on board — locally over Wi-Fi and Bluetooth, without any internet.
Area news
Official notices to skippers for your waters — closures, lock and bridge works, wrecks. The app automatically shows the notices at your current position; coverage keeps growing (many areas across Northern and Western Europe). In the Area tab next to tides and weather; when starting a passage the app warns about closures in your area.
Voyages & legs
Voyages group legs together — with cash box (expenses, deposits, fair settlement by email), rotating watch schedule and crew management including documents.
Ship management
Maintenance tasks with intervals and due dates, repair log with costs, spare-part inventory with stowage location, boat papers as scans.
Inventory & stowage
Know where everything lives on board: rooms and storage places on the deck plan (below & on deck), items with photo, best-before status and target stock, safety gear with inspection dates. Shortages become a printable procurement list — and in your Kielwasser cockpit you maintain everything on your computer, the app syncs.
Celestial navigation
A sextant in your pocket: sun line of position and fix as with almanac and sight reduction — the app computes ephemerides, corrections and the intercept method fully offline. And with no sextant at all: photograph sun and horizon with the camera, tap both — done (beta). Your backup when GPS is jammed, and the perfect training tool.
Lean, fast & private
Built fully native — no cross-platform engine, no ad SDKs, no trackers. That keeps the download small (a fraction of many competitors), the app fast and your data yours: iCloud, no third-party server.
Anchor watch
Geofence alarm if the anchor drags — with continuous GPS recording and log entries on dropping and weighing anchor.
Photos & export
Passage photos with position and caption; PDF reports (summary or detailed), yearly collections, HTML export.
iCloud sync
All data — passages, photos, boat, crew, cash box, settings — automatically on all your devices. New iPhone? Everything is simply there.
Kielwasser integration
Create your ship’s log right from the app, publish passages with chart, numbers, log and photos in one tap, write posts with photos.
Sharing & live position
Share cards in the Kielwasser design for Instagram stories, passage links with automatic previews for WhatsApp & co. — and if you like, your log shows live where you are sailing (🔴 opt-in, ends automatically with the passage).
Ship profile & log counter
Model, MMSI, ATIS, owner and a boat photo with your own tile crop — everything flows into your Kielwasser ship profile automatically. The ship’s log reading lives on the boat and pre-fills at passage start.
Nautical references — in 11 languages
Beaufort scale, flag alphabet, navigation lights, GMDSS radio templates and audible sound signals per COLREGs (horn, bell, gong). Plus the complete manual — app, references and help in 11 languages.
NMEA 0183 — Connect your instruments directly
Connect via Wi-Fi to your NMEA gateway. Wind, depth, water temperature, pressure and heading are read directly from your instruments and saved automatically in the logbook. The on-board barometer tracks the 3-hour trend and warns of a storm in good time when pressure drops – the alarm rings via the on-board alarm link on the iPhones on board that stay awake during a watch — entirely without internet.
TCP/IP · Auto-connect · No extra hardware neededThree roles. One app.
Whether you own a boat with a full NMEA setup, charter for a spontaneous holiday, or run a professional fleet — Rubberduck adapts to every role on board, without compromise.
Boat Owners
- Complete voyage archive with GPS track, weather and distance — runs automatically in the background, even with the screen locked
- Group multiple legs into a voyage — see the full picture of a sailing season at a glance
- Maintenance planner with custom intervals — never miss an oil change, impeller or rig check again
- Repair log and spare parts inventory always at hand — even without mobile signal in the harbour
- Built-in anchor watch with configurable radius and alarm — protects the boat overnight without needing the screen unlocked
- iCloud Sync keeps all data up to date across iPhone and iPad — voyages, maintenance, documents and photos, all in one place
- Your own ship's log on the web: publish voyages to Kielwasser with one tap — with a boat profile, live position for those back home and shareable voyage cards
Charter Sailors
- No pen, no paper: GPS track, weather, wind and miles sailed are recorded fully automatically — from the very first metre
- The Cash Box splits shared costs fairly among the crew — fuel, marina fees, provisions — and calculates the final settlement automatically
- Never forget the packing list: start from ready-made categories or build your own — synced via iCloud to every crew member's device
- Plan night watches with the built-in Watch Schedule — fair shifts, clearly assigned, synced to every crew member's device
- Tidal data is detected automatically for the nearest station via GPS and logged during the voyage — especially useful in the North Sea and along Atlantic coasts
- Currency converter with live rates for 30+ currencies — available offline too, ideal for sailing abroad
- At trip end, generate a complete logbook PDF with one tap — as a keepsake or to hand back to the charter company
- 11 languages supported — ideal for international crews where not everyone speaks the same language
Charter Companies & Yacht Clubs
- Uninterrupted GPS track of all voyages with weather and logbook — clear, timestamped documentation for damage claims, groundings or insurance cases
- Conduct safety briefings in a structured and documented way — guests confirm with a signature, record saved with date and participants
- Maintenance planner and repair log per boat — transparent service history for every vessel in the fleet
- Document engine hours and tank levels at every handover — boat condition recorded at start and end, no disputes
- Store boat documents and crew certificates digitally — accessible offline, no paper folders needed on board
- Guests can publish their trip reports with chart and photos to Kielwasser or your own website — real content, no effort from you
- iCloud Sync gives an overview of the entire fleet across all devices — voyage history, maintenance status and tank levels always current
Now on the App Store.
For iPhone & iPad · iOS 18+
📱 Now on the App Store.Available in 11 languages: German, English, Spanish, French, Italian, Danish, Swedish, Norwegian, Dutch, Arabic and Chinese.
More about the app and the boat: sy-rubberduck.de