Froude Number
Dimensionless speed ratio that drives wave-making resistance behaviour.
Froude number Fn
0.163 -
Formula, assumptions, and limits
Cargo ships Fn 0.15–0.22 (displacement). Semi-displacement hulls Fn 0.3–0.7; planing craft Fn > 1. Wave-making dominates resistance beyond Fn ≈ 0.25.
Symbol legend
| Symbol | Meaning | Unit | Source |
|---|---|---|---|
| Ship speed | m/s | derived from knots | |
| Gravitational acceleration | m/s² | 9.81 | |
| Waterline length | m | hydrostatics | |
| Froude number | - | result |