Kongsberg Simrad SN90 Reference Manual page 21

In purse seine operations, the large frequency bandwidth makes the SN90 ideal for both
mackerel and tuna, and even for herring.
Trawlers have for many years relied on high resolution echo sounders - such as the
Simrad ES70 - to find and estimate their catch. The disadvantage with echo sounders
is the fact that they look straight down.
The SN90 offers the high resolution
of an echo sounder, but also a
large horizontal range that allows
you to find fish - even close to the
bottom - from a distance of several
hundred meters. The high frequency
bandwidth makes the SN90 ideal for
species like pollock, cod and saith.
During the search phase, a forward
looking SN90 is a very efficient
tool for all trawlers. Since the
transducer is placed in the vessel's
bow, the SN90 will not suffer from
the acoustic noise generated by the
hull, machinery and propellers.
The physical installation angle of the
transducer must be determined based
on the depth in the vessel's normal
fishing waters. Even with a fixed installation angle, the SN90 will serve well in other
waters too due to the swath and tilt functionality.
Tip
A hull unit may be provided as an option. It allows you to lower and hoist the transducer.
SN92HPX, SN93HPX: A special version of the transducer housing is available for
use on a hull unit. Two trawl hydrophones are added for use with a catch monitoring
system. Both hydrophones point aft. The trawl hydrophone offers a 50 degrees horizontal
beam and a 30 degrees vertical beam. This specific beam pattern is especially suited for
trawling.The wide coverage area reduces the need for careful alignment. This provides
optimal reception from sensors on a bottom or pelagic trawl.
The SN90 system offers the same user interface and operating software as our other
sonars, echo sounders and catch monitoring systems. This enables easier and faster
training of new users.
• The echo presentations are optimised for multiple displays. Provided that you have
connected additional displays to your Processor Unit, you can use the
function to take any sonar view and place it on a separate display. When you move a
view to another display, it will automatically be scaled for the best possible result.
381294/E
Simrad SN90
Docking Views
19