Description
Subtract tideAboveDatum from measuredDepth for datumDepth.
A vertical datum supplies the zero level from which a height or depth is measured. Changing that zero shifts the reported number without moving the physical surface.
Subtract tideAboveDatum from measuredDepth for datumDepth.
When to use this tool
Use Sounding Datum Uncertainty Sign when you need a height conversion with a known datum offset.
How to use the tool and how it works
- Enter measuredDepth, tideAboveDatum, depthUncertainty, tideUncertainty, independent. Use the units and conventions below.
- Run the tool. Correct any format, range, or cross-field input error before interpreting the output.
- Read datumDepth, combinedUncertainty. Use the output convention below.
Subtract tideAboveDatum from measuredDepth for datumDepth. Combine nonnegative depth and tide uncertainties by root-sum-square when independent is true, otherwise by their sum.1
| Input field | Meaning and units | Accepted input |
|---|---|---|
| measuredDepth | Measured Depth | Required. Finite number. |
| tideAboveDatum | Tide Above Datum | Required. Finite number. |
| depthUncertainty | Depth Uncertainty | Required. Finite number; minimum 0. |
| tideUncertainty | Tide Uncertainty | Required. Finite number; minimum 0. |
| independent | Independent | Required. Boolean. |
| Output field | Interpretation | Returned shape |
|---|---|---|
| datumDepth | Datum Depth | Required. Finite number. |
| combinedUncertainty | Combined Uncertainty | Required. Finite number. |
{
"input": {
"measuredDepth": 10,
"tideAboveDatum": 2,
"depthUncertainty": 3,
"tideUncertainty": 4,
"independent": true
},
"output": {
"datumDepth": 8,
"combinedUncertainty": 5
}
}Limitations and assumptions
- The independence flag and uncertainty interpretation are caller assumptions; this does not estimate correlations or survey accuracy.
- Inputs must satisfy both the field types and the cross-field conditions above. Invalid input causes an error; a successful false flag or documented placeholder is a different result.
- Numeric calculations use binary floating point unless exact decimal-integer arithmetic is explicitly stated. No hidden measurement tolerance or decimal rounding is added; nonfinite or out-of-contract results are rejected. Numeric signed-zero results are exported as zero.
Alternative or Complementary methods
Obtain location-specific datum relationships and uncertainty from the responsible survey or hydrographic authority.
References
Similar or alternative tools
- Nautical Sounding Keel Datum Shift
Add transducerBelowSurface to sounding for waterDepth, then subtract draft for underKeel.
- Tide Height Datum Offset
Add sourceDatumElevation minus targetDatumElevation to heightAboveSource to obtain heightAboveTarget.