Wherever wind and tide take us — and what stays behind.
View Passages →Our Hanse 370 — at home on the Ijsselmeer and the North Sea
Passionate cruising sailor with limited vacation time, so unfortunately still somewhat restricted when it comes to real long-distance voyages. The idea for this app and portal came about during my sailing trips, always based on my own needs. Whether it's regional reports, lock times, harbor information, or water levels. Questions like "Can I make it through the mudflats if...are there alternative harbors, what's plan B..." The logbook topic was always in the background, plus every weekend the question of what to take with me, what do I have on the boat...so the whole thing grew, and I hope to provide added value to other sailors and "boat enthusiasts" - I look forward to any exchange about boats and suggestions for improving the app/portal. Fair winds! Chris
Read the logbook on Kielwasser →Selected passages — recorded with the Rubberduck app
All passages in the ship's log on kielwasser.blog →
All passages in the ship's log on kielwasser.blog →
Cruising knowledge on Kielwasser: Harbour search · Cruising areas · Locks · Official notices
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.
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.
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.
Wind, depth, water temperature and more straight from your boat network (NMEA 0183 over WiFi) — logged automatically every 15 minutes.
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).
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 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.
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 group legs together — with cash box (expenses, deposits, fair settlement by email), rotating watch schedule and crew management including documents.
Maintenance tasks with intervals and due dates, repair log with costs, spare-part inventory with stowage location, boat papers as scans.
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.
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.
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.
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.
Geofence alarm if the anchor drags — with continuous GPS recording and log entries on dropping and weighing anchor.
Passage photos with position and caption; PDF reports (summary or detailed), yearly collections, HTML export.
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 Create your ship’s log right from the app, publish passages with chart, numbers, log and photos in one tap, write posts with photos.
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).
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.
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.
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 neededWhether 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.
For iPhone & iPad · iOS 18+
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
