NorthStar Navigation EXPLORER 435 - Manual (Page 23)

Northstar Explorer 435/438 Installation and Operation Manual 23
5-4 Sonar A-Scope display
To show the A-Scope display, select Sonar
A-Scope and press . Use this to analyse the sonar
data in detail and optimize the Gain settings. The user can define the level of the weakest and
strongest echoes to be shown on the sonar displays,
by using the Gain setting. See section 4-3 Gain, for
more information.
The strength of an echo at a particular depth
is shown by the length of the horizontal line at
that depth. A strong echo produces a long line
whereas a weak echo produces a short line.
Fish recognition
The echo strengths shown on the A-Scope can
be useful in recognising the type of fish. Different
species of fish have different sizes and shapes
of swim bladders. The air in the swim bladder
reflects the ultrasonic pulse, so the strength of
the echo varies between fish species according to
the size and shape of the swim bladder.
When fishing among a school of fish and
catching them, note the fish species and the
strength of the echo that it returns on the
A-Scope. Then, when that particular echo is seen
at future times on the fishfinder, it is likely to be
the same fish species.
Divider line
between
sonar history
and A-Scope
Gain setting
(strongest
echo for
display)
Gain threshold
(weakest echo
for display)
To show the Fuel display, select Fuel and press .
(See section 3-3 Setup > Fuel for information about
setting up the fuel values. If the number of engines is
set to 0, the fuel features are turned off.)
Used shows total fuel used since this was last
reset with the Clear Used command.
Remaining shows the amount of fuel
remaining in the tank(s).
Flow shows the fuel consumption per hour.
For twin engine installations, the fuel flow for
each engine is shown separately. This is useful
for checking that both engines are under the
same load.
Economy is the distance travelled per unit of fuel
used. The fishfinder calculates this from the boat
speed and fuel used. The bigger this number, the
better the fuel economy. Adjust the throttle and
trim to achieve the best fuel economy. Note that
the Explorer 438 uses a paddlewheel transducer
to measure speed, used to calculate the fuel
economy. Therefore, calibration of the boat
speed measurement is essential for an accurate
fuel economy reading. See section 3-8 Setup >
Calibrate.
5-5 Fuel display (Explorer 438 only)