## Wind Load Calculator

Use this calculator to compute the force of the wind on a given surface area:

# Explanation

It is natural to assume that if the wind speed increases from 5 to 10 mph then its force will double. But that isn't correct. The effective force of the wind actually increases 400%! If the wind further increases to 15 mph, then the effective force is 900% greater than it was at 5 mph.

The generic formula prescribed by the American Society of Civil Engineers for calculating wind load is Wind Pressure Per Square Foot x Surface Area in Square Feet, where:

Wind Pressure Per Square Foot = .00256 x Wind Velocity in MPH^{2}

Sailors quickly learn this once they realize that sailing in 15 mph of wind is completely different than sailing in 5 mph. The difference is so dramatic that most sailors won't even venture out in winds much over 15 mph.

The purpose of this page is to provide a resource to help compare different wind velocities and predict how those changes may affect a given boat.

## Beaufort Scale

The Beaufort Scale is a measurement of wind velocity based on observed conditions at sea and on land. It was developed in 1805 by Francis Beaufort, a Royal Navy officer, and remains a very practical and handy means of expressing wind velocity without the need for instuments. The table below shows the 13 levels of the Beaufort Scale:

Number | Name | Wind |
---|---|---|

0 | Calm | < 1 knot |

1 | Light Air | 1-3 knots |

2 | Light Breeze | 4-6 knots |

3 | Gentle Breeze | 7-10 knots |

4 | Moderate Breeze | 11-16 knots |

5 | Fresh Breeze | 17-21 knots |

6 | Strong Breeze | 22-27 knots |

7 | Near Gale | 28-33 knots |

8 | Gale | 34-40 knots |

9 | Strong Gale | 41-47 knots |

10 | Storm | 48-55 knots |

11 | Violent Storm | 56-63 knots |

12 | Hurricane Force | >= 64 knots |