The Explorer W315 provides a genuine analog display giving key wind functions Apparent Wind Angle (AWA) and Speed (AWS) True Wind Angle (TWA) and Speed (TWS)* VMG* Maximum Wind Speed (Apparent) High Wind Speed Alarm * Function requires valid data from Northstar S310, M310 or NMEA 0183 source. W315 accepts either NMEA 0183 VHW (Boat Speed), VTG or RMC (SOG) for calculation of true wind.