Tools of the Trade: By Speed of Wind

It goes without saying that a sailing ship lives and dies by the wind. A dead calm can be as deadly as a hurricane if the conditions are right – or wrong as the case may be. Knowing the general velocity of wind, as well as myriad other factors of weather and position, can keep ship and men safe in even the most trying of circumstances.


Our seafaring ancestors, who roamed the uncharted waters of the world, knew what they were dealing with by simple signs that could be spotted even on the smallest of vessels. Here’s a list of what to look for with regard to wind from the early 19th century via Peter H. Spectre’s A Mariner’s Miscellany:

Smoke rises vertically, undisturbed – the wind is calm, blowing less than 1 knot.

Smoke drifts toward horizontal – light airs, 1 to 3 knots.

A man feels the wind on his skin – slight breeze, 4 to 6 knots.

A light flag or pendant extends from a staff or yard – gentle breeze, 7 to 10 knots.

Wind raises light, loose items on deck such as dust, ash, paper – moderate breeze, 11 to 16 knots.

A standard flag snaps briskly – fresh breeze, 17 to 21 knots (under good way with steering room, this is certainly the sailor’s favorite condition for making time).

Wind is heard to whistle through the rigging – strong breeze, 22 to 27 knots.

Up on deck, particularly on the quarter or poop, walking against the wind is difficult – moderate gale, 23 to 33 knots.

The insistence of the wind actually impedes the ship’s progress – fresh gale, 34 to 40 knots.

With this last and any wind strength thereafter, finding safe anchorage or taking open ocean precautions becomes imperative. Note that a hurricane force wind in this period was defined as anything over 65 knots in velocity.

Header: Ship in Storm via VOC Historical Society