I have been using Skydemon with Navigation this year in a motor glider and have been very pleased with it generally. I took part in the Wenlock Olympian Gliding competition this year and, having no specialist glider nav/software system on my low performance wooden vintage glider, used Skydemon for the competition tasks. The task in question was a 150km triangle with designated turning points. However the handicapping system allows gliders to turn onto the next leg before reaching the turning point as long as they enter a 'barrel' or circle round the turning point. The size of the barrel depends on the handicap of the glider, so lower performance gliders can turn earlier and fly a shorter course than higher handicap better performance gliders. 

I used Skydemon's 'range from TP' indicator to establish the distance from the turning point. The size of the 'barrel' in my case was 3.2km. So I waited until the range from TP indicator showed 3km, waited a few more seconds for luck and turned. Unfortunately the data logger showed that I turned at 3.4km and so I incurred a 50 point penalty, dropping me from second to fifth place. Oh well, its for fun really and a useful learning curve. I assume that when the range to turning point shows 3km it is actually anywhere between 3.5-2.5km.

Would it be possible to include an input for a variable radius circle round TP, accurate to less than 0.1km and a warning when in the circle?

Mike