NorthStar Navigation Explorer 660 - Manual (Page 31)

Northstar Explorer 660 Installation and Operation Manual 31
! WARNING
8-1 Using the Explorer 660
The Explorer 660 uses a sonar transducer
attached to the hull. The transducer generates
an ultrasonic pulse (sound that is above the
hearing range of the human ear), which travels
down towards the bottom at a speed of about
4800 ft/sec (1463 m/sec), spreading out into a
cone shape.
When the pulse meets an object, such as a fish or
the bottom, it is partly reflected back up towards
the boat as an echo. The depth of the object
or bottom is calculated by the Explorer 660 by
measuring the time taken between sending a
pulse and receiving the echo. When an echo has
been returned, the next pulse is sent.
The Explorer 660 converts each echo into an
electronic signal, displayed as a vertical line of pixels.
The most recent echo appears on the extreme right
of the display, with the older echoes being scrolled
towards the left, eventually disappearing off the
display.
The scroll speed depends upon the water depth
and scroll speed setting. See sections 15-3 and
section 8-2, for more information.
The appearance of echoes displayed are affected
by:
• the Explorer 660 settings
(see section 8-5)
• echoes (different fish types, different bottom
types, wrecks and seaweed; see section 8-2)
• noise (water clarity and bubbles; see section
8-2).
Cruise, Fishing and Manual Modes
The Explorer 660 has three sonar
operating modes:
• Cruise mode: Use this when on the move.
The Explorer 660 automatically adjusts its
settings to compensate for water clarity and
to display the bottom.
• Fishing mode: Use this when fishing. The
Explorer 660 automatically adjusts its settings
to compensate for water clarity and to best
display fish, the bottom and other details.
• Manual mode: Use this to fine-tune the
Explorer 660 settings by hand. Best results are
often achieved in manual mode, but practice
and experience are required to obtain the
optimum settings for different conditions.
To select an operating mode, press GOTO/AUTO
and select the mode. When you select Manual
mode, the Explorer 660 reverts to your last
manual settings.For more information on
operating modes and the Explorer 660 settings,
see section 8-5.
8 Sonar fishfinding: Introduction
This section explains how to interpret the sonar
displays, when and why to use the different
frequencies and how fish are detected and
displayed. It also describes Gain and Range and shows
examples of some of the different sonar displays.
Use the automatic Cruise or Fishing modes
when learning to use the Explorer 660 or
when travelling at speed.