B&G Deckman - Manual (Page 52)

Navigation options
3.25
displayed. This is an easy way to check you have entered tidal
information for all the reference ports you might need.
Navigation options
You have a number of options as to the sources of data you use for your
navigation functions in Deckman, such as variation, current/tide, boat
position and so on. Hit menu>view>options and you will be presented
with the dialog shown in Figure 3.13.
Variation is the magnetic variation for your area in the form dd.d.
Preceding the number with a minus sign will set it to West, a positive
Figure 3.13