AV8
Take the approx windspeed at your flight level, divide by 2, the resulting number is your MAX DRIFT
Using the clock code, imagine that one complete revolution round the face of your wristwatch is MAX DRIFT
Substitute the degrees off heading for seconds on the clock
This method relies on the notion that anything over 60 degrees off is considered MAX DRIFT and is based on 120 kt cruise
eg 20 degrees = 20 seconds = 1/3 of MAX DRIFT
40 degrees = 40 seconds = 2/3
60 degrees or more = MAX DRIFT
It does get a bit tricky when the wind is 'behind' you, i.e, 120 degrees off....in this case you need to consider how much the wind is off your tail...here it would be 60 degrees so again MAX DRIFT
Actually you can use the one method for Head wind calcs too. The trick here is too remember that there are only 90 degrees of angle to use and to calibrate the 'clockface' in knots of wind
eg heading 360 wind 030/20
drift = 30 'seconds' worth of 10 (20/2)
headwind = 60 'seconds' worth of 20
therefore drift = 5 degrees, headwind = 20 knots
eg heading 030 wind 075/25
drift = 45 (3/4) of 12 = 9 degrees (say 10)
headwind = 45 (3/4) of 25 = 18 knots (say 20)
In all cases round up or down as convenient, the wind is after all only a guestimate!
I realise that reading this it may seem a little confusing but read it again, draw a few examples on paper and it will soon come to you.
Hope this helps
JWF