|How does ice surfing compare to wind surfing? How fast can ice surfers go? How is it possible for ice surfers to travel into the wind?|
How do ice surfers go so fast?
SuChin surfs the bright, white ice.
Segment length: 7:00
Grab your board and hit the beach-it's surfing time again. But instead of baggies and a tank top, you might want to put on a parka and thermal socks, because the kind of surfing we're talking about only happens on solid water. That's right, the topic is ice surfing, and it's the hottest sport on frozen lakes around the world.
Ice surfing is really a hybrid sport, mixing the speed of ice boating with the agility and power of wind surfing. The ice surfing board is similar in size and shape to a big skateboard. Most boards have two blades in the back for stability and either one or two blades in the front to control the steering. Just like the wheels on a skateboard, the blades on an ice surfing board are mounted on flexible "trucks" so the rider can control the steering by leaning forward or backward while standing sideways on the board.
As with ice skates and ice boats, the blades on the ice board are quite sharp on the bottom, putting a great deal of pressure on the ice below. This pressure, combined with the friction between blade and ice, causes some of the ice to melt directly below the blade. A thin film of water lubricates the ice under the blade, which helps it glide smoothly over the ice. This really cuts down on the drag and means that the ice surfer is actually riding on liquid water, not solid ice. Because there is far less friction involved, ice surfers can go much faster than wind surfers, often approaching speeds of 113 kilometers (70 miles) per hour.
Just like wind surfers, ice surfers power up on an ice board by using a sail. In fact, most ice boards use the same type of sail as wind surfing boards. But because there is less friction on the ice, an ice surfer can get away with a much smaller sail. To make the board go, the rider sets her or his back to the wind and sheets in by pulling in on the boom-a bar attached to the bottom of the sail. As the sail catches the wind, the board starts moving forward. The highest speeds are attained when moving nearly perpendicular to the wind. By trimming the sail at the correct angle, the ice surfer can actually move almost three times faster than the wind itself. It's not possible to sail directly into the wind, but by tacking at an angle, surfers can zigzag across the wind, heading upwind little by little.
1. How do you think an ice surfing board would work if it were fitted
with skis instead of blades?
2. Do you think it would be possible to adapt the design of an ice board to make a two-passenger commuter vehicle? How might you do it?
boom horizontal post on the bottom of the sail
which the rider uses for control
drag force of resistance between the bottom of the blade and the surface it's riding on
luff flapping of the sail when it is pointed directly into the wind or the sail is sheeted out
mast vertical pole, extending up from the board, that supports the sail and boom
power up to lift the sail and capture wind to get the board moving
sheet in to pull in on the boom so that the sail can capture wind and move forward
sheet out to let the wind out of the sail, thereby slowing the board
tack to sail in a zigzag pattern across the wind to move upwind
trim sail to adjust the sail to either capture more wind or let it out
Additional sources of information
Angling Your Attack
Discover the best angle for sailing into the wind.
While it is impossible to sail directly into the wind, it is possible to move upwind by sailing at an angle across the wind. This is called tacking. Construct a simple model sail and test it to see what your minimal tack angle is.
1. At what angle did the sail first fill with air when you were running into the wind? What does this tell you about the minimum angle at which you can sail into the wind?
2. When you were sailing with the wind, at what angle did the sail appear to have the most power?
3. Can you calculate how far you would have to sail to move directly upwind one kilometer?
4. Why do you get maximum power out of a sail when it is at an acute angle to the wind?
How does the amount of water or surface roughness affect how much friction there is between a blade and the ice surface? Freeze water in a rectangular pan. Try dragging a brick across the ice, using a spring scale to measure the amount of force needed. What combination of water and ice produces the least resistance? Which produces the most?
Ever since the Egyptians first built the pyramids, people have been looking for ways to reduce friction. Today, many superlubricants exist for specialized purposes. Research some of these products and explain why each can work under certain conditions.
Research how sail designs for boats have changed over time. What were some of the disadvantages of old-fashioned square riggers compared to modern vessels? Why do racing yachts have three or four different sails? What purpose does each one serve?
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