Forget the whizz wheel, unless your are sh*t hot at using it you will be wasting your time. Concentrate instead on radio nav and handy rules of thumb.. .. .Don't forget you can use radio aids during the diversion, so be very clear as to how to use these and which ones you will use during the test. . .. .A rule of thumb I use for calculating drift is that the max drift you will encounter (ie if the wind if 90 degs. to track) is 2/3 of the wind at height transposed to degrees e.g. if the wind is 15kt then your max drift will be 10 deg. This is not 100% accurate, but it is likely to be more accurate than you can fly.. .. .Also, have you measured your thumb? Mine's 10NM from tip to knuckle, quite handy for shorter diversions. . .. .Finally, remember that the examiner is not looking for perfection, he is looking for safety and a reasonable degree of accuracy. During my test I almost screwed up my diversion as the actual wind was very different from forecast, during the debrief the examiner suggested that I could have routed via a nearby VOR and then used that to track straight to the diversion point.. .. .Good Luck!