The problem is rarely the device (whether GPS, compass.... or even a gun). Operator error is the reason, and the only reason, that GPS doesn't work 99 point-a-high-something percent of the time. (And failing to know that your unit is not communicating properly is part of the operator's responsibility. Various software add-ons might be a separate issue; can't say from experience.)



Sometimes, the air you 'let in'matters less than the air you 'let out'.