Description
Add chartedDepthMeters and tideHeightMeters and subtract nonnegative vesselDraftMeters for underKeelClearanceMeters.
A clearance margin compares available vertical space with occupied space and any explicit allowance. Depths, water levels, and structure elevations must share compatible datums.
Add chartedDepthMeters and tideHeightMeters and subtract nonnegative vesselDraftMeters for underKeelClearanceMeters.
When to use this tool
Use Tide Level Minus Draft Margin when you need a transparent component of a vertical clearance calculation.
How to use the tool and how it works
- Enter chartedDepthMeters, tideHeightMeters, vesselDraftMeters. Use the units and conventions below.
- Run the tool. Correct any format, range, or cross-field input error before interpreting the output.
- Read underKeelClearanceMeters. Use the output convention below.
Add chartedDepthMeters and tideHeightMeters and subtract nonnegative vesselDraftMeters for underKeelClearanceMeters.1
| Input field | Meaning and units | Accepted input |
|---|---|---|
| chartedDepthMeters | Charted Depth Meters | Required. Finite number. |
| tideHeightMeters | Tide Height Meters | Required. Finite number. |
| vesselDraftMeters | Vessel Draft Meters | Required. Finite number. |
| Output field | Interpretation | Returned shape |
|---|---|---|
| underKeelClearanceMeters | Under Keel Clearance Meters | Required. Finite number. |
{
"input": {
"chartedDepthMeters": 4,
"tideHeightMeters": 1.5,
"vesselDraftMeters": 3
},
"output": {
"underKeelClearanceMeters": 2.5
}
}Limitations and assumptions
- Depth and tide require a compatible datum; squat, motion, uncertainty, safety reserve, and actual navigational suitability are not included.
- 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
Use current surveys, water levels, vessel data, and approved operational margins for an actual passage decision.
References
Similar or alternative tools
- Fathom Depth Chart Label
Require nonnegative depthFathoms, append the fathom label, and multiply by 1.8288 for depthMeters.
- Rating Curve Control Shift
Add signed stageShift to observedStage for adjustedStage.