Last night my friend Eric sent me the below e-mail & I asked him if I could post it here. Boat path seems to play a big roll in skiers success at 38off & beyond ,this opens a great discussion .
The goal of skiing is to maintain a constant speed at all times through the course – by the laws of physics ,this is the most efficient way to run a pass.
Many times when an experienced driver pulls a skier , it seems easy and slow for the skier, yet the course times were exact..Why does that happen ?..
Here is the explanation why we experience an easy time behind certain drivers....... and it proves that those drivers are actually driving CORRECTLY by the laws of physics and not just helping the skier unfairly with a “ ski school swerve”.
Below is the physics formula for why a boat driver’s direction of travel in the course from boat guide to boat guide is so critical for keeping the skier at a constant speed (avoiding accelerations and decelerations) as he rounds the balls. I drew it out on paper and simply put, if the boat is pointed away from the skier as he hooks up at the ball, this decreases the alpha angle which decreases the skier’s speed relative to the water. At short rope lengths this is critical to give the skier ample time to get set in a pull position after the ball versus pulling him off the ball.
Another way to write the equation is:
V2= V1 x Alpha/Beta
V2 is skier speed
V1 is boat speed
Alpha and Beta angles are explained above.
Simply stated, the skier’s relative speed to the water depends on the speed of the boat multiplied by the ratio of the boat’s angle to the rope(alpha) divided by the angle of the ski’s direction relative to the rope(beta). The skier is at maximum angle behind the boat (beta angle is high) and the alpha is low because the rope is directly behind the boat,,,,,but then the skier’s angle to the rope decreases(Beta decreases) as skier turn back toward the boat while the (alpha angle increases)......as a result, the ratio goes up and the skier speed will increase(according to the formula) unless the driver points the boat away to decrease the alpha angle. Conversely, if the skier keeps the ski going outward as long as possible (keeping the beta angle as high as possible), this keeps his speed relative to the water constant and slower despite feeling more load on the rope. Keeping outward direction as long as possible on the ski reduces speed on the skier and makes the pass seem slower. Unfortunately many of us try to ski a pass as narrow as possible because we get inpatient ......as a result the pass seems really fast because we never got good Beta angle !!!!!
That is why pointing the boat away from the skier is not cheating(even though the boat whitewash looks closer to one boat guide than the other)..... it simply keeps constant tension on the line and a constant speed to the skier. Anybody with little experience can keep a boat straight down a course, but with more experience driving we learn to minimize the Alpha angle at the right time.
Just a BOS ex-con tryin to stay outta trouble.
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