Garmin gpsmap 178 Manuale Utente

•  Set Up Sonar — jumps to the Sonar tab of the Main Menu, which contains sonar configura-

tion settings that should not require frequent change. You may also press MENU twice from any 
screen, then highlight the ‘Sonar’ tab using the ARROW KEYPAD. Press RIGHT on the ARROW 
KEYPAD to access the selection fields. Each time the Setup Menu is accessed, the unit returns to 
the last edited selection field. 

1.   Using the ARROW KEYPAD, highlight the desired field and press ENTER and the available options 

appear.

2.   Highlight the desired setting and press 

ENTER.

3.   Press QUIT to return to the Sonar Page or previous page.

 Fish Symbols — allows you to determine how the graph displays underwater targets and back-
ground information. If Fish Symbols are set to ‘Off’, the unit displays all of the available information 
about the underwater environment. If a fish symbol is selected, the graph displays only the infor-
mation related to that symbol. Actual fish returns may not always appear as perfect arches (like in 
simulator mode), due to the speed, fish orientation, and/or other conditions. 
 Water Type — since sound waves travel through ‘Fresh’ and ‘Salt’ water at different rates it is neces-
sary to select the ‘Water Type’ to ensure accurate readings on the unit.
 Depth Number — controls the efficiency of the digital depth update rate. ’Fast Update’ updates 
more quickly and is recommended for low-noise, deeper water (>50 ft.). ‘Auto’ is best for shallow 
water or high noise areas, has a slower screen update and is best used if you travel a wide variety of 
depths.