I asked a very similar question about a month ago, some guy named Wayne responded with this, and it fixed me right up.
Navionics does not have any GPS co-ordinates and you can't put them on Navionics, your unit's GPS does. GPS is not mapping and mapping is not GPS.
The format has to match to enter the correct numbers.
You can change the Google Earth format to match the unit format or change the unit format to match the Google Earth format.
GPS formats are:
Degrees Minutes Seconds-----DD MM SS
Degrees Minutes Decimal Minutes----DD MM.MMMM
Degrees Decimal Degrees-----DD.DDDDD
There are no fish in sonic pond EDIT: Except 1 20lb catfish