G'day Tracie, welcome to GPS Power. A standard GPS PND (Personal Navigation Device) of the type we deal with in this forum won't be accurate enough for that unfortunately. Even aviation devices used for precision instrument landing approaches don't get under 3 metres in some conditions and they have LAAS and WAAS augmentation.
This rar file contains a PDF explaining it. It's to do with the problems of using a gps device for measuring a race course but the accuracy discussed is applicable to your friend's situation laying out a fence: [Only registered and activated users can see links. ]. Credits to the 'Smuttynose' website:
He'd be better off with a dumpy level to shoot a bearing and then measure conventionally between posts i'd reckon.Code:Please Login or Register to see the links