Maybe the software I developed is already more than you are looking for. Check www.farmergps.com for some information.

I created this program to help me with challenges using a sprayer and foam markers. We have lots of waterholes and some bush on our land, so when I did 2 rounds on one waterhole, I was already getting close to the next. Going around the second got me overlaps and a messy pile of foam drops :-).

Anyway FarmerGPS became a birdseye view guidance system over the years. It also includes option to mark rocks, weed patches or whatever, do area calculation, some record keeping etc.

It is based on using a laptop and uses any standard GPS receiver (outputting NMEA). Some customers use a simple Garmin 18-5Hz unit for about $ 150.- (others do not consider this receiver accurate enough). Adding the cost of FarmerGPS at 299.- you are ready to go, assuming you own a laptop.

Johannes