Description
Divide nonnegative inflowSpeed by positive shipSpeed and subtract the quotient from one.
Marine speed, thrust, and propeller ratios depend on a declared reference frame and coherent units. A scalar term usually describes only one part of vessel performance.
Divide nonnegative inflowSpeed by positive shipSpeed and subtract the quotient from one.
When to use this tool
Use Wake Fraction Water Inflow Term when you need one explicit marine performance ratio or residual.
How to use the tool and how it works
- Enter shipSpeed, inflowSpeed. Use the units and conventions below.
- Run the tool. Correct any format, range, or cross-field input error before interpreting the output.
- Read wakeFraction. Use the output convention below.
Divide nonnegative inflowSpeed by positive shipSpeed and subtract the quotient from one.1
| Input field | Meaning and units | Accepted input |
|---|---|---|
| shipSpeed | Ship Speed | Required. Finite number; strictly above 0. |
| inflowSpeed | Inflow Speed | Required. Finite number; minimum 0. |
| Output field | Interpretation | Returned shape |
|---|---|---|
| wakeFraction | Wake Fraction | Required. Finite number. |
{
"input": {
"shipSpeed": 10,
"inflowSpeed": 8
},
"output": {
"wakeFraction": 0.19999999999999996
}
}Limitations and assumptions
- Use the same speed unit and reference frame; negative wake fractions are allowed when inflow exceeds ship speed.
- 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 measured operating data and a vessel-specific propulsion model for performance predictions.
References
Similar or alternative tools
- Propeller Slip Measured Advance Term
Multiply positive pitch by positive revolutionsPerSecond for idealAdvanceSpeed, then return 1 - advanceSpeed / idealAdvanceSpeed as slipFraction.
- Propeller Advance Coefficient Reference
Divide advanceSpeed by positive revolutionsPerSecond times positive diameter for advanceCoefficient.