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.
MitReeder is here: bookings, costs, votes and documents of your boat co-ownership now in the app too — including the role that shows who you are connected as.
See all releases →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.
Quick Entry
One tap is enough: while a passage is active, a banner sits ready at the bottom. Log typical events like "reef in" or "watch change", switch propulsion and sails or write free text — every entry is saved with time and position. Custom templates per boat, synced across your devices. Entries can be edited, deleted and added afterwards with a chosen date and time. Photos are part of it too: add a picture straight from the quick entry via camera or library — camera shots are also saved to your Photos app.
Dictation
Under sail you rarely have a hand free: log entries can be spoken instead of typed. Tap, speak, done — the text lands in the free-text field and stays editable. The recogniser is given the sailing terms and the harbours, locks and seamarks of your area beforehand, so it gets names right instead of guessing. Everything is computed on the device, even without a connection — no recording leaves your phone. If you like, download a dedicated recognition model (approx. 465 MB): far better on place names, and it covers all eleven app languages.
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. Tide information via WorldTides (own access required).
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 device on board — locally over Wi-Fi and Bluetooth, without any internet.
Area news
Official notices to mariners for your waters — closures, lock and bridge works, wrecks, drifting buoys. The app automatically shows the notices at your position; coverage reaches from Northern and Western Europe across the Adriatic and the Mediterranean to the Red Sea and the Persian Gulf, complemented worldwide by the official maritime safety services. New: while under way the app alerts you when you come closer than two nautical miles to a closure — the check runs on the device, so it works without a connection. You set the notice radius and warning distance yourself.
Harbour search & anchorages
Harbours, marinas and anchorages within 10 nautical miles — or search the whole directory. The detail page shows an aerial view, facilities, weather, the wind-shelter forecast for the berth, AIS traffic in front of it and community depths: soundings other crews have measured on the spot. The search is free; with Premium you save the visible map area offline — harbours, detail pages and map tiles stay on board, even without a connection.
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.
GPS Integrity — Spoofing & Jamming Alert
New in version 4.5.1 (iOS first, Android to follow shortly): the app reliably warns you as soon as your GPS position becomes implausible — whether from GPS jamming (a jammer) or GPS spoofing (deliberate manipulation). You get a clear message with an explanation and an action recommendation based on severity — up to advising you to navigate by visual bearing and compass for a while. Anomalies are written to the logbook automatically. This works with the device GPS alone, entirely without NMEA; with a connected NMEA setup (e.g. WLN10) it checks even deeper — satellite signal strength (C/N0), precision values and dead reckoning. Switch it on or off anytime. Especially valuable in areas with known GPS interference such as the Baltic or the eastern Mediterranean.
Lean, fast & private
Built fully native — no cross-platform engine, no ad SDKs, no trackers. That keeps the download small, the app fast and your data yours: on iOS in your iCloud, on Android in your Kielwasser account — nowhere else.
Anchor watch
Geofence alarm if the anchor drags — with continuous GPS recording and log entries on dropping and weighing anchor.
Photos, videos & export
Passage photos and videos with position and caption; PDF reports (summary or detailed), yearly collections, HTML export.
Multi-device sync
All data — passages, photos, boat, crew, cash box, settings — automatically on all your devices. On iOS via iCloud, on Android via your Kielwasser account. New device? Everything is simply there.
Free 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.
Ship QR code
A weatherproof code on your boat: whoever scans it sees the boat, the skipper and the home port — and can write to you without ever seeing your phone number or email address. The most common case: the boat lies alone in the harbour or rafted up alongside — whoever needs to get out, wants to raft up or sees something chafing reaches you at once. The message arrives in the app and by email, notes in other languages are translated. Print template as a PDF in three sizes, plus a vector version for the print shop. Sold the boat? Renew once — the old code stops working immediately. Not only for the boat: dinghy, outboard, folding bike — several codes per log, each with its own name and photo, all pointing to the same ship.
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.
Premium ★ MitReeder — boat co-ownership
If the boat belongs to several people, a dedicated area appears in the app: a booking calendar colour-coded per member, costs with a photographed receipt, votes with majorities by share or by head, work hours and the group's documents — insurance, berth contract, minutes. The area only appears when the logbook belongs to a co-ownership; crew never see it. Managed on mitreeder.de, with everything on hand in the app.
★ MitReeder is licensed separately: €149 per boat per year at mitreeder.de — independent of Premium in the app.
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 devices 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 & Co-Ownerships
- 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
- Device sync keeps all data up to date across all your devices — voyages, maintenance, documents and photos, all in one place (on iOS via iCloud, on Android via your Kielwasser account)
- 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
- Ship QR code for the pontoon: whoever notices something at your boat — a chafing line, a raft-up that needs to leave — scans it and writes to you. Without seeing your phone number or email. Print template as a PDF in three sizes, plus a vector version for the print shop
- Messages from the pontoon arrive in their own list behind the envelope — visible on every tab, with a push notification, and messages in other languages arrive translated
- Wind and rain as an hourly matrix instead of cards: when it picks up, when the rain arrives, how long it stays — with amount and probability, hour by hour
- If the boat belongs to several people, MitReeder runs the co-ownership: booking calendar, costs with receipts, votes, work hours and the group's documents — all in the More tab of the same app, no second program
- The annual accounts come out of it: who carried how much and who owes whom what is calculated from what was entered over the season anyway — by shares, by heads or by nights booked
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 automatically 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
- Cruising area information and guides for your sailing grounds: official notices on lock and bridge closures, water levels, marine weather — at your position, no searching
- The forecast as an hourly matrix — it answers the question “do we leave early tomorrow or after lunch?” by itself
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
- Device sync gives an overview of the entire fleet across all devices — voyage history, maintenance status and tank levels always current
- A weatherproof QR code per vessel: harbour masters, neighbouring boats or guests reach you right at the boat — without a mobile number on display at the pontoon. Reports collect in one list, with a push notification
Get the app
For iPhone, iPad & Android
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