Raymarine hsb2 PLUS, Owner'S Handbook Manual

Page: 97 / 228

Chapter 4: Fishfinder Operations 4-1
In
trod
uc
tion
Chapter 4: Fishfinder Operations
4.1 Introduction
Basic Fishfinder operation, including a description of the different display
options, was given in
Chapter 3 . This chapter helps you the get the most from
your Fishfinder. It describes how to fine-tune the image and use the controls to
get additional information.
This chapter covers the following topics:
• Interpreting and Adjusting the Fishfinder Image, including fish and bot-
tom indications, using the white line feature and adjusting gain (sensitiv-
ity)
• Viewing Data Windows
• Setting up and Using Alarms for fish, shallow water and deep water
• Using a VRM to Determine Depth and Distance from Boat of a particular
spot
• Placing Waypoints
• Using the Man Overboard (MOB) function
4.2 Interpreting and Adjusting the Fishfinder Image
The hsb
2
Plus Series Fishfinders use sound waves (sonar) to find fish and show
the bottom of a lake or sea. The transducer sends high-frequency sound waves
down into the water; these sound waves strike fish, the bottom, or other objects
in the water and return as echoes. The fishfinder interprets these echoes to
present an image of the fish and bottom.
The strength of echoes is indicated by different colors (or shades of gray in the
monochrome L755RC Plus). You can use this information to determine the
size of fish and the bottom structure. Other objects in the water, such as debris
and air bubbles, also return echoes; these echoes are generally weaker than the
fish or bottom echoes and produce background noise or
clutter on the
Fishfinder display.
The Fishfinder provides controls to reduce the background noise and to adjust
the way in which echoes of different strengths are displayed. The color
Fishfinders also let you select the background color and remove the display
colors for weaker echoes. Refer to
Changing the Brightness & Color Settings
(Color LCD) on page 3-6 for details on these two functions.