Every boat is a survey ship.
Your echo sounder measures the bottom several times a second, and throws every reading away. SoundingKit keeps them. Multiply that by a thousand boats and the white parts of the chart start filling in.
OF THROWN AWAY
Nobody ever came to measure.
Hydrographic offices survey where the cargo goes: shipping lanes, commercial ports and the approaches to them. A three-metre bay with no freight traffic has never been near the top of anyone's list.
Plenty of those bays were last sounded with a lead line, by a man in a rowing boat, when the chart was still drawn by hand. The sand has moved since. Nobody went back to check.
Meanwhile a hundred yachts anchor there every summer, every one with a working echo sounder, every reading discarded the moment the screen redraws.
That is the whole idea. Stop throwing it away.
the bottom it left behind
Illustration. Real charts from the plugin go here once the first passages land.
Three things happen, none of them to you.
It works while you don't
The plugin reads the sounder and the GPS you already have. No window to watch, no button to press, no connection required. A season of recording fits on the boat with room to spare.
It catches up when you do
The first time you get a signal, your passage joins everyone else's. Nothing is discarded and nothing is ever deleted — a sounding taken today will still be there in ten years, when better tools exist to read it.
It comes back as contours
Where boats have been, the bottom has a shape. Including the anchorage your official chart leaves politely blank.
Nothing recorded is ever deleted.
Soundings are kept exactly as the instrument reported them. Depth lines are worked out on top and can always be worked out again — so the raw record outlives every tool that reads it.
That matters more than it sounds. A bank that shifted between 2024 and 2029 is only visible because both years were kept. Throw away last season to save space and you have destroyed the one thing a chart cannot show you: what changed, and how fast.
None of it belongs to us in any meaningful sense. It was measured by the boats that were there, and it goes back to the boats that come next — including the ones that will read it with tools nobody has written yet.
Every season stacks on the last
Layers accumulate. None is ever removed.
Schematic. The live figures are in the table below.
Depth, time, place. Nothing else.
No name, no boat name, no crew list. But where a boat anchors is still information about where that boat lives, so the decision stays with you.
Draw a box and go quiet
Mark the water around your home berth and nothing recorded inside it ever leaves the boat. The filter runs before anything reaches the disk, so there is nothing to delete later.
Or share it late
Publish a week behind, or a month. The soundings still count, but nobody reading them can work out where you are tonight.
You almost certainly have all of it.
Nothing new to buy and nothing new to wire. The plugin listens to what your instruments are already saying to each other.
| OpenCPN | 5.8 or newer |
| Echo sounder | reporting depth over NMEA |
| GPS | any, already connected |
| System | Windows · macOS · Linux |
| Disk space | from 200 MB |
| Internet | only to swap data |
Start with one passage.
Install it, sail the way you were going to sail anyway, and watch your stretch of coast stop being blank.