Description
Use the slope (aftDraft - forwardDraft) / (aftPosition - forwardPosition) to evaluate draft at referencePosition.
Vessel draft, loading moments, and free-surface terms describe different parts of hydrostatic behavior. Their signs, reference positions, and dimensional bases must be stated before comparison.
Use the slope (aftDraft - forwardDraft) / (aftPosition - forwardPosition) to evaluate draft at referencePosition.
When to use this tool
Use Vessel Trim Reference Midpoint when you need a supplied trim, loading, or hydrostatic component.
How to use the tool and how it works
- Enter forwardDraft, aftDraft, forwardPosition, aftPosition, referencePosition. Use the units and conventions below.
- Run the tool. Correct any format, range, or cross-field input error before interpreting the output.
- Read referenceDraft, gradient, midpointPosition. Use the output convention below.
Use the slope (aftDraft - forwardDraft) / (aftPosition - forwardPosition) to evaluate draft at referencePosition. Also return that gradient and the longitudinal midpoint.1
| Input field | Meaning and units | Accepted input |
|---|---|---|
| forwardDraft | Forward Draft | Required. Finite number; minimum 0. |
| aftDraft | Aft Draft | Required. Finite number; minimum 0. |
| forwardPosition | Forward Position | Required. Finite number. |
| aftPosition | Aft Position | Required. Finite number. |
| referencePosition | Reference Position | Required. Finite number. |
| Output field | Interpretation | Returned shape |
|---|---|---|
| referenceDraft | Reference Draft | Required. Finite number. |
| gradient | Gradient | Required. Finite number. |
| midpointPosition | Midpoint Position | Required. Finite number. |
{
"input": {
"forwardDraft": 4,
"aftDraft": 6,
"forwardPosition": 0,
"aftPosition": 100,
"referencePosition": 50
},
"output": {
"referenceDraft": 5,
"gradient": 0.02,
"midpointPosition": 50
}
}Limitations and assumptions
- Positions require a common datum and aftPosition greater than forwardPosition. Extrapolation is allowed; curved waterlines and loading changes are not modeled.
- 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
Consult vessel-specific hydrostatic and stability information under the relevant loading condition for a complete assessment.
References
Similar or alternative tools
- Vessel Trim Longitudinal Slope Factor
Divide aftDraft minus forwardDraft by positive length for a signed slope.
- Nautical Draft Forward Aft Average
Average nonnegative forward and aft drafts for meanDraft and subtract forward from aft for trim.