Froude Number

Dimensionless speed ratio that drives wave-making resistance behaviour.

Resistancehydrodynamics

Ship speedknLength (LWL)m

Froude number Fn: 0.163 -

Changing the inputs requires JavaScript. The calculator above shows its default inputs and result. The formula, symbols, and regulatory sources are shown in the Formula section below.

Formula, assumptions, and limits

Fn = \frac{V}{\sqrt{g \cdot L}}

Symbol	Meaning	Unit
$V$	Ship speed	m/s
$g$	Gravitational acceleration	m/s²
$L$	Waterline length	m
$Fn$	Froude number

Source: SNAME PNA Vol II

In short

Dimensionless speed ratio that drives wave-making resistance behaviour.

Learn the theory Ship resistance and powering