signalk-opentide

A SignalK plugin that contributes depth + SOG + position observations to OpenTide — a worldwide open tidal-prediction network at https://opentide.io.

Note — position reporting fixed in v0.4.2. Earlier versions never sent a moving vessel's position to the network, so a mobile contributor's tide fit had no location and didn't count. Our apologies if your earlier contributions weren't being recorded — from v0.4.2 on, position is reported correctly and your data counts.

What it does

• Subscribes to environment.depth.* and navigation.speedOverGround on SignalK.
• Queues every sample locally in a plain append-log file (so offline stretches don't lose data — zero native deps, no npm install build step on a Pi).
• Posts batches every 60 seconds to OpenTide's ingest endpoint.
• Survives reboots, network outages, and sender crashes — the on-disk queue is the source of truth.

Once the OpenTide engine has enough data, it produces a harmonic tide fit for your spot and ships predictions back. With ≥ 2 confirmed contributors at the same anchorage, the fits fuse to consensus — the predictions get sharper as more boats and stations join in.

All data is licensed CC-BY 4.0.

Two flavours: vessel and stationary station

| | Vessel | Stationary station | |---|---|---| | Position | Read from SignalK's navigation.position | You enter fixedLat / fixedLng in plugin config | | SOG | Read from SignalK's navigation.speedOverGround | Forced to 0 always | | Examples | Live-aboard, cruiser, pilot boat | Marina office roof, harbour piling, dock-mounted depth gauge |

Pick stationary for a fixed sensor that doesn't move and doesn't have a GPS. The plugin will not attempt to read SignalK's GPS path; the configured fixedLat/fixedLng are used instead.

Install

npm install signalk-opentide

Or via SignalK's Appstore tab (Server → Appstore → search "OpenTide").

Pair a station and configure the plugin

1. Visit https://opentide.io/#contribute and click Pair a station.
2. Pick Vessel or Stationary station:
   • For Stationary: enter your latitude/longitude (decimal degrees) and a station name.
3. Copy the generated token (starts with ot_…).
4. In SignalK admin → Server → Plugin Config → OpenTide:
   • Paste the token.
   • Pick the same station type you chose at opentide.io.
   • For Stationary: also fill in fixedLat, fixedLng, stationName.
5. Save. The plugin starts queuing and shipping samples within ~60 s.

You can check progress at https://opentide.io/#status by entering your token.

Plugin status

Visit http://<your-signalk>/plugins/signalk-opentide/diagnostics for queue depth, last response, and last error. The plugin also exposes:

• /plugins/signalk-opentide/token — used by the bundled web app to read the token without it appearing in URLs.
• /plugins/signalk-opentide/lastResponse — most recent successful prediction response (for offline rendering).

How long until predictions show up?

| Hours of data | Confidence tier | |---|---| | 0–24 | Collecting | | 24–48 | Early (preliminary fit; UI shows "*" badge) | | 48 h+ | Good | | 5 days+ | Confirmed | | ≥ 2 confirmed contributors at the same spot | Consensus (fused) |

Privacy and licensing

• The token is anonymous — no Sealink / OpenTide account required.
• Submitted depth + SOG + timestamp data is licensed CC-BY 4.0: anyone may reuse it as long as they credit the OpenTide network.
• The plugin sends NO other SignalK data — wind, battery, AIS, etc. are not forwarded.

Part of the OpenSeas Tech Collective

OpenTide is an open-data project of the OpenSeas Tech Collective alongside SeaLink, KeelWise, and HarbourNow.

License

Plugin code: MIT. Submitted observations: CC-BY 4.0 (set per OpenTide token at pair time).