Chapter 1: Overview 1-3
Chapters 6 provides detailed information for operating the sonar
functions - selecting depth range limits, adjusting gain, color and
STC, setting alarms, using the VRM marker, marks and man over-
board.
Chapter 7 provides information on user maintenance, and what
to do if you experience problems.
The Appendix lists the technical specifications for the DSM250.
What's New
The DSM250 operates much like traditional Raymarine fishfind-
ers. If you are already familiar with our displays, you won’t have
much difficulty using the DSM250. Below is a list of DSM250
features that differ from our traditional fishfinder displays.
• No integral display. You connect the DSM250 to an
hsb
2
PLUS
Radar, Chartplotter, or Fishfinder display unit to show echo
sounder data.
• Digital sonar. The DSM250 employs a digital dynamic adaptive
receiver and transmitter for dramatically improved fish and bot-
tom detection in any water conditions.
• New automatic Gain modes. These automatic modes make the
gain adjustments for you, based on depth and water conditions.
The DSM250 provides three pre-defined automatic gain settings
for Cruising, Trolling, and Fishing. See Adjusting Display Gain
(Sensitivity) on page 6-5.
• Bottom hunt feature. The DSM250 features a digital “Hunt
mode” that automatically searches for the bottom when the
sounder is in Auto Range. Unlike our fishfinder displays, the
DSM250 stays in manual range when placed there—it does not
switch to auto mode by itself. When you are trying to automati-
cally find bottom, you need to have the sounder module set to
Auto Range mode. Refer to Hunt Mode on page 5-18.
• Auto frequency. When set to Auto Frequency, the DSM250 also
alternates frequencies when hunting for bottom. If set for Manual
frequency, the unit does not switch frequencies when bottom
hunting. This differs from traditional Raymarine fishfinder dis-
plays. Details are found in Selecting the Frequency on page 5-19.
• New Auto STC mode. You can now let the sounder unit automat-
ically choose the optimal STC level for reducing background
noise that often appears in shallow water. See STC on page 6-8.