Chapter 6: Sonar Mode Operation; Introduction; Interpreting And Adjusting The Sounder Image - Raymarine DSM250 Owner's Handbook Manual

Chapter 6: Sonar Mode Operation

Chapter 6: Sonar Mode Operation

6.1 Introduction

6.2 Interpreting and Adjusting the Sounder Image

Basic operation, including a description of the different display
options, was given in Chapter 5. This chapter explains how to use
the display unit to show sonar data. 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 Sounder Image, including fish and
bottom indications, using the white line feature and adjusting gain
(sensitivity)
• 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 to a
particular spot
• Placing Waypoints
• Using the Man Overboard (MOB) function
Note: The settings described in this chapter are retained when the
unit is powered off. However, there is a one-minute delay from the
time you change the setting to when the DSM250 places it in memory.
If you power down the sounder less than one minute after making a
change, the setting is lost.
Note: Many of the parameters on the DSM250 have both manual and
automatic modes. The automatic setting takes advantage the hard-
ware's advanced digital technology. As a result, the sounder typical-
ly performs better in automatic mode than in manual.
For better performance, Raymarine recommends that you select
AUTO mode wherever it is an option.
The DSM250 uses sound waves to find fish and show the bottom
of a lake or sea. The transducer sends high-frequency sound
waves into the water; these sound waves strike fish, the bottom, or
other objects in the water and return as echoes. The DSM250
interprets these echoes to present an image of the fish and bottom.
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