today
9 a.m. Doris Niles Humboldt County Science Fair Humboldt State University
read >10 a.m. Annual Juggling Festival Humboldt State University
read >10:30 a.m. Green Jobs Fair College of the Redwoods Downtown Site
read >11 a.m. Baby Read and Grow Program Humboldt County Library
read >1 p.m. Apple Solutions for Small Business See Event Description
read >4 p.m. Young Parent Support Group College of the Redwoods Kinship Site
read >6 p.m. The Tumbleweeds (cowboy songs) Chapala Cafe
read >6 p.m. Bon Swing Libation
read >6 p.m. Annual Pisces Party See Event Description
read >6 p.m. Annual Pisces Party See Event Description
read >7 p.m. The Big Lebowski Arcata Theater Lounge
read >7 p.m. DJ Ray Boiler Room
read >7:30 p.m. Arianna String Quartet Calvary Lutheran Church
read >7:30 p.m. A Midsummer Night's Dream Arcata High School
read >8 p.m. Eureka Symphony Concert Arkley Center for the Performing Arts
read >8 p.m. Humboldt Folkdancers Arcata Presbyterian Church
read >8 p.m. On the Wings of a Dove Carlo Theater (Dell'Arte)
read >8 p.m. Antigone College of the Redwoods
read >8 p.m. So Hum Tales Mateel Community Center
read >8 p.m. Gentle Thunder Arcata Playhouse
read >8:30 p.m. The Last Minute Men (international) Cafe Mokka
read >9 p.m. Taxi (rock & roll) Bear River Casino
read >9 p.m. Vintage Soul (R&B) Cher-Ae-Heights Casino
read >9 p.m. Bump Foundation Pearl Lounge
read >9 p.m. The Brothers Comatose (folk) Six Rivers Brewery
read >9 p.m. The Malone (rock Red Fox Tavern
read >10 p.m. Music by DJ Sidelines
read >10 p.m. DJ Ninja Retro Dance Party Aunty Mo's Lounge
read >previous columns
April 3, 2008
Ancient Mariners
Sailing is an ancient enterprise. Humans used the wind to ...
read >March 27, 2008
Hunting Worms
I recently went big-game hunting in the bay for a ...
read >March 20, 2008
Tsunami Terrors
Understanding the nature of tsunamis could save your life. They ...
read >Photos
Sailing
By Don Garlick
The physics of sailing is outlined in the first diagram, showing the equilibrium between forces. The vector-sum of forces on sail and keel is balanced by the resistance of moving the boat through water.
The speed of a typical 10-meter yacht in winds of 10 and 20 knots, as a function of its angle to the wind, is shown in the second diagram (1 knot = 1.15 mph and 1 mile = 1.6 km). As shown in the third diagram, the length of the yacht is important because the speed of the induced bow wave varies with the wave's length. It is difficult for a boat to exceed the speed of a wave whose wavelength is longer than the boat, because the boat is then attempting to climb up the wave. With sufficient power, however, a speed-boat can ride up upon its bow wave and effectively hydroplane.
Although the maximum speed of a typical yacht is less than the wind speed, high-tech catamaran yachts have reached speeds about twice that of the wind. A windsurfer narrowly beat the yachting record this year with a speed of 49 knots (56 mph). The land yacht record is 117 m.p.h. in 30 m.p.h. winds!




















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