Each line in the DDMMYY.nav file is a one minute average of the
incoming GPS position, along with it's calculated
speed and direction. Note the speed and direction of each one
minute average also uses the 10 minutes prior speed and direction
to smooth the average even more.

DDMMYY.nav columns defined:

1) DD/MM/YY
2) HH:MM:SS
3) latitude:  degree minutes hemisphere
4) longitude: degree minutes hemisphere
5) NAV or MAN: NAV using gps, MAN manual entry
6) speed in knots (average)
7) direction (average)
8) number of GPS fixes to calculate this current line lat and lon

Example:
18/01/14 16:56:31  33 13.8995 N 119 13.0728 W NAV 20.17 239.6 20

1) 18 January 2014
2) 16:56:31 GMT
3)  33 deg 13.8995 minutes North
4) 119 deg 13.0728 minutes West
5) NAV, using GPS unit for navigation
6) 20.17 knots, calculated speed of ship
7) 239.6 calculated direction of ship 
8) 20 GPS fixes used in this one minute average

SIO, LLehmann 25oct2016