Salt & Wire Companion is an Android app for sailors and boat owners, written by marine electrical engineers: anchor alarm, offline navigation with EMODnet bathymetry and topographic maps, weather on the chart, an AIS and VHF receiver from an RTL-SDR dongle, position without GPS, logbook and crew mode. Works without coverage, without an account and without ads. Your data never leaves the phone.

We wrote it for ourselves, for our own passages.

NAVIGATION AND WEATHER
- Navigation: the route is checked against land, wrecks, marks and your draught. EMODnet bathymetry, OpenSeaMap seamarks, topographic maps of Germany, France, Spain, Italy, the Netherlands, Poland, Norway, Sweden and Finland, NOAA charts on US waters.
- Weather on the chart (PLUS): wind and waves, rain and thunderstorm risk, air and water temperature five days ahead from NOAA, on the anchor watch too. One tap saves the forecast for the time without coverage. NASA satellite images. Thunderstorm risk is an estimate.
- Offline maps (PLUS): mark an area and the app downloads the tiles. A world map is built in.
- Compass: heading, speed, position, night mode.
- Position without GPS (PLUS): when GPS is jammed or silent, the dongle listens to beacons, repeaters and AIS, and the app draws the area the boat is in.
- Position by bearings (PLUS) and Tide assistant (PLUS): bearings on charted objects give a fix, two waters from the tables give the tide curve.
- Ports & anchorages (PLUS): from OpenStreetMap, with your own notes.

ANCHOR
- Anchor watch: a drag alarm with a radius you set yourself, running with the screen off.
- Anchoring assistant (PLUS): depth, tide, bow roller and wind give chain length, swing circle and alarm radius.
- Remote anchor alarm (PLUS): rings on a phone ashore.

AIS AND RADIO
- AIS & VHF (SDR, PLUS): an RTL-SDR dongle in the phone is an AIS receiver and a VHF band scanner. The signal comes off your own antenna, not the internet, so ships show without coverage. Ships with name, course, CPA and TCPA.
- AIS over WiFi (PLUS): an AIS receiver on the boat's network, vessels on the chart.

SAFETY
- Man overboard, MOB (PLUS): one button: position, bearing and distance back, alarm to the crew.
- MAYDAY prompter (PLUS): the call with your position read digit by digit.
- Night light identifier (PLUS): tick the lights you see, the app names the vessel and who gives way.
- Ship's barometer (PLUS) and Sea-state meter (PLUS): 48 hours of pressure with a drop alarm, wave height and period from the phone's motion.
- Crew safety briefing (PLUS): lifejackets, raft, extinguishers and gas valve on one page for guests.
- Watch scheduler (PLUS): a reminder before every change.

CREW AND VOYAGE
- Crew access (PLUS): one subscription per boat, the crew sees position, anchor, barometer and log for free, by NFC or code.
- Live position (PLUS): family follows the passage, you send the position by SMS or WhatsApp.
- Boat kitty (PLUS): trip costs split across the crew.
- Logbook PRO (PLUS): an entry every hour under way, PDF export.
- Float plan, Cruise opinion and Fuel log: one page for someone ashore, miles and hours for a licence, fill-ups and range.

SERVICE AND DOCUMENTS
- Maintenance log: photos and voice notes. The microphone only while you record, recordings stay on the phone.
- Reminders by date or engine hours, Tasks, Seasonal checklists, Documentation and parts inventory.
- Diagnostic wizard: electrical faults step by step with a multimeter. Symptom assistant (PLUS): describe the fault in your own words.
- Wire size calculator and Battery bank sizing.
- Boat dossier (PLUS): service history in one PDF. Charter handover (PLUS): check-in and check-out with signatures. Service report and fault report.

Everything stays on the phone, backup when you want. Sharing sends nothing until you switch it on. Modules marked PLUS come with a Google Play subscription with a three-day trial, the rest is free.

A navigation aid, no substitute for official charts or a lookout.