Catch the Wind | The Beaufort Scale
Define the Wind
By Scott Huler, author of Defining the Wind
As you pilot your boat in the sailboat pond at the Catch the Wind exhibit, perhaps you glance at the sign giving Beaufort Scale descriptions of the wind: Beaufort 0, for example, is Calm: “Smoke rises vertically.” Perhaps that’s why your sailboat won’t move. If “wind extends light flag,” it’s Beaufort 3, a Gentle Breeze, which at 8-12 mph is strong enough to put “leaves and small twigs in constant motion,” to say nothing of the pirouettes it generates in your little boat.
Gosh, that’s lovely – poetic, powerful language that uses sensory detail to convey vital information about the wind. It’s beautiful and well worth reading, even studying. But if you’re saying, “Pretty enough, but that’s still not helping me control my boat,” you’re moving directly towards the core of Beaufort’s magnificent scale.
The Beaufort Scale has been around since British Admiral Sir Francis Beaufort first scrawled it in his log aboard the Woolwich in 1806. Of course it extends back before that – Beaufort actually cribbed it from the work of a guy named Dalrymple, who had in turn been influenced by designers of wind scales as far back as Tycho Brahe in the sixteenth century.
It extends forward too, the model of the descriptive scientific scale, informing the language of the Mercalli Earthquake Intensity Scale (“V… Sleepers awakened. Liquids disturbed, some spilled”) and, most familiar to North Carolinians, the Saffir-Simpson Hurricane Scale (“Category Three: Mobile homes and poorly constructed signs are destroyed”). The land version of the Beaufort Scale used on the sign by the sailboat pond was written in 1906 – by a group not of poets but of engineers. The scale’s poetic language has since inspired poetry, music, art, even dance.
But most interesting at the sailboat pond is that the Beaufort Scale began as a communication tool: a working scale. Because one sailor’s log entry of “windy” might be another’s “breezy” – and because as shipping spread worldwide in the early 19th century such information became very important – Beaufort systematized those descriptions. Beaufort’s scale, from 0 (“calm”) to 12 (“hurricane”) described not twigs or even waves but the sail a standard ship of the time would bear. Sailors, with their vast experience, would feel of the wind, know that such a wind would enable them to run 5 to 6 knots with all sails up, and know they were at level 4, Moderate Breeze. Windy enough to reef the topsails? That’s 6, Strong Breeze. By the time you’re reefing the mainsail, you’re at 8, Fresh Gale.
The scale encouraged sailors to use their experience to accurately describe the strength of the wind. So when you learn that to maintain control of your little sailboat in a stronger wind you have to keep the sail close – or that to get speed in a light breeze you have to spread it wide – you’re just doing what Sir Francis wanted you to do: using your sail, and your senses, to define the wind.