Garmin GPSMAP 238 Sounder - Manual (Page 24)

14
Getting Started
Sonar Page
Sonar Page
The Sonar Page is where your GPSMAP 188/188C/238 Sounder becomes a powerful fi shfi nder/
fl asher. The top left of the screen contains data fi elds, while the Adjustment Bar above the data fi elds
allows direct access to the settings most commonly changed while using the Sonar Page. The middle
of the page contains a right-to-left moving sonar image of the water beneath your boat (Items appear
as they pass under your transducer. Those items on the right side of the screen are closer to you than
those on the left.). Along the right side of the screen is an adjustable scale which refl ects the depth of
the area being displayed. If the unit does not detect a transducer attached to the unit, a “Sonar Turned
Off” message appears across the Sonar Page. You may also show a sonar fl asher and color bar on the
right side.
The sonar display may also be set to show a split screen view of a zoomed portion of the sonar,
bottom lock (display scaled from the bottom up), or a combination of these options (see pg. 34). For
example, you may choose to show dual frequency at a 2X zoom (Dual 2X) on one half and normal
range dual frequency (Dual) returns on the other half. The current display mode will be displayed at
the bottom of each sonar display.
On color models, sonar returns show as red (strongest), then oranges (strong), yellows (medium),
greens (weaker) and blues (weakest). On grayscale models, stronger returns appear darker and weaker
returns lighter. The ‘ Fish Symbols’ option (see page 38) allows you to view the actual sonar data, a fi sh
symbol, or a combination of both. ‘Fish Symbols’ appear as green. When the unit is set to ‘Dual’ (see
page 35), the appearance of the fi sh symbols (and simulated fi sh returns) will change. Fish symbols
from the narrower beam (200kHz) will be solid (or narrow returns), but the returns from the wider
beam (50kHz) will be hollow (or wide returns). Simulated fi sh icons are displayed in three different
sizes. Actual fi sh returns may not always appear as perfect arches, due to the speed, fi sh orientation,
and/or other conditions.
More on understanding the Sonar Page may be found on pages 111 and in Appendix I.
Dual frequency returns
Sonar Page
Data Fields
Depth
Scale
Adjustment
Menu
Simulated
Fish Arch
Bottom
Whiteline
Thermocline
Center beam
return Outer edge
beam returns
Frequency
mode
Flasher
188188C238 Manual Part 1.indd 14 6/30/2003, 3:34:31 PM