How to Properly use the Tuned Windage Compensator
How to Properly Use your Kenton Industries Custom Windage Dial
Thank You for purchasing your Kenton Industries Custom Windage Dial. These simple instructions will help you better understand the proper use of the knob for target or hunting applications. Your knob will be marked similar to the one shown in Figure 1.
In the example for Figure 1, if your target is 300 yards away, with a 10mph 90 degree crosswind blowing you would turn the knob until the “300” lined up with the indicator on the scope body and you would be corrected for windage at that distance. You correct right of left depending upon which direction the wind is crossing your target.
Your knob is calibrated for a 10 mph crosswind. But you can use the knob under differing wind condition with equal success. Simple math can be used to correct for a difference in wind speeds. For instance, if the wind is blowing at 5mph you simply half the distance to 150yards, because 5mph is half of 10mph. Likewise if the wind is blowing at 20mph you would double the distance to 600 yards, because 20mph is double 10mph.
This can be done for any wind speed. If a 7mph wind is blowing, this is 70% of 10mph, so you would dial 70% of 300, which is 210 yards (300x .70 = 210 yards.) If a 12mph wind is blowing this 120% or 10mph, so you would dial 120% of 300, which is 360yards (300 x 1.2 = 360yards)
What about changes in Wind direction?
If the wind is not blowing at a 90 degree angle its affect on the bullet will be less depending upon the actual angle of the wind with respect to you and the target. Again we can use a bit of simple trigonometry and math to make a correction for the crosswind component. The effective crosswind component is the sine of the angle times the actual wind speed. Refer to Figure 2
Fortunately, the math is relatively easy for the most common angles.
The Sine of 30 degrees is .500
The Sine of 45 degrees is .707
The Sine of 60 degrees is .866
The Sine of 90 degrees is 1.00
For a 10mph wind blowing 30 degrees off your Right shoulder and across the target 300 yards away, the correction would be sin30 x 10mph = .5×10 = 5mph. 5mph is half of 10mph so correct for ½ of 300 yards or dial to 150yards right correction
For a 10mph wind blowing 45 degrees from your left and across the target 300 yards away, the correction would be sin45 x 10mph = .707 x 10 = 7mph. This is 70% of 10mph, so you would dial 70% of 300, which is 210 yards left correction (300x .70 = 210 yards.)
For a 10mph wind blowing 60 degrees from your left and across the target 300 yards away, the correction would be sin60 x 10mph = .866 x 10 ~ 9mph. This is 90% of 10mph, so you would dial 90% of 300, which is 270 yards left correction (300x .90 = 270 yards.)
Putting it all together!
With the basic tools in place we can now dial in the appropriate yardage for any wind speed and direction.
Your target is 400 yards away; the wind is blowing 6 mph, from 30 degrees over your left shoulder. What correction do you make?
The sine of 30 degrees is .500 so .5 x 6mph = 3mph. 3mph is 30% of 10mph, so 30% of 400yards is 120 yards. (400x .30 =120) You would adjust your windage dial to 120 yards left correction.
One last example;
Your target is 275 yards away; you have a wind blowing 45 degrees into you from the right at 14mph. What correction do you make?
The sine of 45 degrees is .707 so .707 x 14 ~ 10mph. Your knob is calibrated for 10mph so just turn the knob to 275 yards right correction!