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Use computed water depth

Computed Depth is an optional fallback source for vessels that do not have a depth sounder connected to BoatKit. It combines the conservative charted depth at the vessel's trusted GPS position with the current harmonic prediction from the nearest installed tide station.

Computed Depth is an estimate, not a measurement. Do not use it as a substitute for a working depth sounder, official chart information, local knowledge, visual piloting, or safe under-keel-clearance practices.

Before you start​

Computed Depth needs all of the following aboard the vessel:

  • A trusted GPS position in BoatKit.
  • Detailed LOD0 chart tiles installed for the vessel's location.
  • An installed tide-station dataset with harmonic constants for a nearby station.

The calculation runs locally from installed data and does not require an internet connection. Chart and tide datasets still need to have been synchronized before going offline.

Enable and prioritize Computed Depth​

  1. Open Settings > Vessel & Data > Sensors.
  2. Expand Water Depth.
  3. Enable Computed Depth with its checkbox.
  4. Drag it to the desired place in the preferred-source order.

BoatKit uses the first healthy enabled depth source in that order. Leaving Computed Depth below a physical sounder makes it a fallback. Moving it above a physical source makes the estimate eligible to become the general depth value first.

Open the Computed Depth settings control to see its current status and a summary of the calculation.

How the estimate works​

BoatKit uses the shallowest charted depth area containing the current GPS position, rather than interpolating nearby sounding points. It then adds the predicted tide height for the current time. A result below zero is presented as zero depth.

To avoid unnecessary device work, BoatKit does not continuously load and parse detailed chart tiles just because the option exists. The calculation starts only when Computed Depth would win the configured depth-source priority or when a Viewer is actively requesting its exact value, such as while showing the Sensors settings row or a gauge configured for that source. Parsed tiles are kept in a small cache while they remain useful.

What you will see​

When the estimate is available, Computed Depth appears like another water-depth source in the priority list. A gauge driven by it shows Computed as the source label. BoatKit uses the same Computed label for a gauge driven by Predicted Water Speed.

An unavailable estimate remains invalid rather than presenting a stale value as measured data. The settings row reports reasons such as a missing trusted GPS position, unavailable detailed chart depth, or unavailable tide prediction.

Important limitations​

  • Charted depths may be old, generalized, or referenced to a datum that differs from present local water conditions.
  • Harmonic tide predictions are not observed water levels and do not account for wind, pressure, river flow, seiche, or other weather-driven effects.
  • The nearest available tide station may not represent conditions at the vessel.
  • GPS error can place the vessel in the wrong chart depth area, especially near a shoal, channel edge, or shoreline.
  • The calculation does not detect temporary obstructions, silting, vegetation, debris, wakes, squat, or the vessel's actual under-keel clearance.

If the estimate is unavailable, verify the trusted GPS source and confirm that detailed charts and tide data have been synchronized for the operating area. Use the status shown in the Computed Depth settings before changing the source order.