Lowrance lms-350a 操作ガイド

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PRESET SONAR AND GPS
The LMS-350A has a built-in memory that saves all settings such as
sensitivity, chart speed, keel offset, speed calibration, and more. Virtually
all settings except for waypoint and route information is saved in this
memory. (Waypoints, icons,  and routes are saved in a separate memory.)
Therefore, every time you turn the unit on, the settings are exactly as you
left them.
However, you can return the LMS-350A to it's factory settings using the
preset feature. This returns all sonar and GPS receiver settings at the
same time. To use this feature, press the MENU key, then press the key
next to the "More" label until the fifth menu page appears. Next, press the
key adjacent to the "PRESET SONAR AND GPS" label. The screen will
clear and return to the sonar display with the factory settings.
MENU - PAGE 6
ADJUST KEEL OFFSET
The keel offset feature lets you
compensate for the transducer's
location. Since this sonar unit
measures the water depth from
the face of the transducer, there
can be a significant difference
between the actual water depth
and what is displayed on the
unit. For example, suppose you
mount a bolt-thru-hull  trans-
ducer on the bottom of the boat.
When you launch the boat you
find that this location places the transducer three feet below the surface
of the water. Therefore, the depth sounder always reads three feet
shallower than the actual water depth. (In other words, if the bottom is 50
feet deep, the depth sounder will read 47 feet, if the transducer is mounted
three feet below the surface.) The difference between the depth sounder's
reading (47 feet) and the actual water depth (50 feet) is called the keel
offset. In this example you will use a 
positive
 keel offset.
Another time you may wish to change the keel offset is if you want to know
the bottom depth from the deepest part of the boat. For example, by
careful measurment you find that the deepest part of the boat is four feet
below the face of the transducer. By setting a 
negative 
keel offset of four
feet, the sonar unit will show the bottom depth from the lowest part of the
boat to the bottom.