today
8:30 a.m. Audubon Society Field Trip See Event Description
read >9 a.m. Arcata Farmers' Market Arcata Plaza
read >9:30 a.m. Discovery Walk: Unknown Waterfront See Event Description
read >9:30 a.m. Manila Dunes Restoration Manila Community Center
read >10 a.m. Manila Dunes Guided Walk Manila Community Center
read >10 a.m. Library Book Sale Humboldt County Library
read >10 a.m. Dia de los Muertos and Mexican Folk Art Sale Private Eureka home
read >10 a.m. Final Arcata Farmer's Market Arcata Farmers' Market (off the plaza)
read >11 a.m. Donlin Foreman Dance Workshop Dell'Arte
read >2 p.m. Humboldt Coastal Nature Center Draft Trails Plan Walk Stamps House
read >5 p.m. Bati Zado and Show Redwood Raks World Dance Studio
read >6 p.m. The Tumbleweeds Chapala Cafe
read >6 p.m. Ali Chaudhary (jazz duo) Libation
read >6:30 p.m. Not Evil, Just Wrong Humboldt Area Foundation
read >7 p.m. Guitar Stan (country) Old Town Coffee & Chocolates
read >8 p.m. Guitar Orchestra of Barcelona Arkley Center for the Performing Arts
read >8 p.m. Stones in His Pockets Arcata Playhouse
read >8 p.m. A Christmas Carol North Coast Repertory Theater
read >8 p.m. Donna Landry Swing Dance Moose Lodge
read >8 p.m. North Coast Wind Ensemble Fulkerson Recital Hall at HSU
read >8:30 p.m. The Last Minute Men (international) Cafe Mokka
read >9 p.m. Ian McFeron Band (folk rock) Six Rivers Brewery
read >9 p.m. The Michael Paul Band WAVE @ blue lake casino
read >9 p.m. The Generatorz (classic rock) Central Station Cocktail Lounge
read >9 p.m. Taxi Bear River Casino
read >9 p.m. VJ Itchie Fingaz Pearl Lounge
read >9 p.m. Jack Ruby Presents + Blue Street + Acufunkture (DIY rock) Jambalaya
read >9 p.m. 2nd Annual Scorpio Bash The Red Fox Tavern
read >10 p.m. Music by DJ Sidelines
read >10 p.m. DJ Icy Hot Aunty Mo's Lounge
read >10 p.m. Jemimah Puddleduck (rock) Humboldt Brews
read >10 p.m. White Manna + Midday Veil + The King Salmon Duo (rock) Jambalaya
read >11 p.m. Radio Moscow (psychadelic blues) + Mosquito Bandito (one-man surf/garage) The Alibi Lounge and Restaurant
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
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The vector-sum of forces on sail and keel is balanced by the resistance of moving the boat through water. Diagram by Don Garlick.
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Speed is a function of the boat's angle to the wind. Diagram by Don Garlick.
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The length of the yacht is important. Diagram by Don Garlick.
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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