Invite-only beta · starting in Fiji
Every passage makes the next one safer.
Your depth sounder already measures the seabed every second. SonarBuddy turns those readings into a shared, open map of the anchorages, passes and reef edges cruisers actually use, and shows where the charts are wrong.
Free during the beta. No ads. We never sell your data.
Charts in the Pacific are old. Cruisers have the newest data.
Many Pacific charts come from surveys made decades ago, and free seabed models are smoothed guesses near coasts and reefs, exactly where you anchor. Meanwhile every cruising boat logs thousands of fresh soundings a day and throws them away. SonarBuddy keeps them, checks them, and shares them so the next boat in knows what you found.
How it works
Connect once
SonarBuddy reads depth and position from your instruments over the boat's Wi-Fi. B&G, Simrad and Lowrance plotters, the PredictWind DataHub, or any NMEA 0183 source. Read-only: it never sends anything to your electronics.
Sail as normal
Logging runs in the background on every passage. Beta boats can also upload logs they already have.
Colour in the map
Your track turns the map white with measured depths and contours. Where boats disagree with the seabed model, it's flagged for everyone.
Plan with real data
Draw a leg and SonarBuddy shows how much of it boats have measured, and every stretch that differs from the model by more than you choose (20% by default).
Safety comes from many boats, not one
- Agreement builds trust. Areas covered by several independent boats get higher confidence; a single boat's reading is marked "check this".
- We show the gaps. Coverage is always visible, so "no warnings" is never mistaken for "safe".
- Quality checks on every sounding. Spikes, poor GPS and false echoes are flagged automatically; your offsets are applied so depths read from the waterline.
- Honest about limits. SonarBuddy is a planning aid, not a chart, and never says "safe". Keep a proper lookout and use official charts for navigation.
Anonymous by design
- No names on the public map. Soundings appear under an anonymous ID, never your boat's name.
- A fresh ID every passage. Even an anonymous track can't be followed from one passage to the next.
- You choose who knows it's you. Share your tracks with buddy boats you approve; nobody else can link them to you.
- Your raw logs stay private. Only processed, anonymised soundings are shared. You can delete your data at any time.
Open data, owned by the community
We'll charge for convenience features one day, never for the data. Soundings will also be shared, anonymised, with the international crowd-sourced bathymetry effort (IHO DCDB / Seabed 2030), so your passages help map the world's oceans, not just ours.
Join the waitlist
SonarBuddy is invite-only while we test it with boats in Fiji. Tell us a little about your boat and we'll send an invite as places open. Buddy-boat groups and rallies welcome.
We'll only email you about your SonarBuddy invite. Questions: mail@sonarbuddy.com
Questions
Is SonarBuddy a chart?
No. It shows what boats have measured and where that differs from a free global seabed model. It is not for navigation and never tells you an area is safe.
Which boats can take part?
Any boat with a depth sounder whose data reaches the boat's Wi-Fi: B&G, Simrad and Lowrance plotters, the PredictWind DataHub, or any NMEA 0183 over TCP. Garmin and Raymarine support is being tested. You can also upload NMEA logs.
What does it cost?
Free during the beta. The data will always be free and open; any future paid features will be conveniences, not access to soundings.
Who can see where I've been?
Nobody can tell a track is yours unless you approve them as a buddy boat. The public map shows anonymous passages, with a fresh ID each time.
Where does it work?
Anywhere, but we're starting in Fiji, where the seabed model is included and the first boats are sailing. More regions follow as boats join.