Humminbird 987C SI COMBO User Manual
28
SIDE IMAGING TECHNOLOGY: HOW IT WORKS
Side Imaging sonar uses two very precise sonar beams that are directed to either side
of the boat and “illuminate” the bottom contour, structure, and fish, and display results
in a “picture-like” image.
of the boat and “illuminate” the bottom contour, structure, and fish, and display results
in a “picture-like” image.
• Side beams are extremely narrow from front to back, and provide “thin slices” of
the bottom for high resolution imaging.
• Side beams look out to a range of 240 feet, with a depth limitation of 100 feet.
The main benefit of Side Imaging sonar to anglers is that it provides an overall survey
of a large area of water. This gives you a better understanding of the bottom
topography and how structure is oriented for more efficient fishing. Saltwater anglers
pick up precise details of popular fishing structure like wrecks, reefs, humps and drop-
offs, as well as being able to spot bait balls in open water. Freshwater anglers can see
fish-attracting structure such as timber, stumps, rocks and creek beds.
of a large area of water. This gives you a better understanding of the bottom
topography and how structure is oriented for more efficient fishing. Saltwater anglers
pick up precise details of popular fishing structure like wrecks, reefs, humps and drop-
offs, as well as being able to spot bait balls in open water. Freshwater anglers can see
fish-attracting structure such as timber, stumps, rocks and creek beds.
SIDE IMAGING: ON THE WATER INTERPRETATION
Use the following side imaging examples to help you interpret the side imaging
display.
display.
Imaging Tips
Boat speed: Side imaging is best performed at boat speeds between 2 to 6 mph. If the
boat is stationary, the same information is displayed over and over. If the boat is
moving very quickly, there will be gaps between the strips of information. The best
boat speed to use will depend on the side range selected. Slower speeds are good for
longer ranges, while faster speeds can be used at shorter ranges.
boat is stationary, the same information is displayed over and over. If the boat is
moving very quickly, there will be gaps between the strips of information. The best
boat speed to use will depend on the side range selected. Slower speeds are good for
longer ranges, while faster speeds can be used at shorter ranges.
Boat navigation: It is important to understand that when the boat turns, successive
beam strips to one side will begin to overlap and the strips on the other side will fan
out, providing some distortion to the image. Because of this, the best imaging
performance is produced by straight line navigation and minimal side-to-side boat
motion (i.e. wave induced, etc.) This applies to navigation by either the main engine or
the trolling motor. Minimize turning time and avoid wave action that induces large
side-to-side rocking of the boat. For example, if there is a lot of wave activity, try to
move the boat so that it is perpendicular to the waves instead of parallel with the
waves in order to minimize the side-to-side rocking of the boat.
beam strips to one side will begin to overlap and the strips on the other side will fan
out, providing some distortion to the image. Because of this, the best imaging
performance is produced by straight line navigation and minimal side-to-side boat
motion (i.e. wave induced, etc.) This applies to navigation by either the main engine or
the trolling motor. Minimize turning time and avoid wave action that induces large
side-to-side rocking of the boat. For example, if there is a lot of wave activity, try to
move the boat so that it is perpendicular to the waves instead of parallel with the
waves in order to minimize the side-to-side rocking of the boat.
Beam Coverage: When there is an area directly under the boat that does not have SI
beam coverage, this area will be covered by the standard 50/200 kHz down-looking
beam and displayed in the Sonar views. The net effect of this, on the display, is that a
single object may appear as two separate entities when in reality, it is one continuous
object. See Submerged Bridge: A Closer Perspective and the Submerged Bridge graphics
on the next page for examples of this.
beam coverage, this area will be covered by the standard 50/200 kHz down-looking
beam and displayed in the Sonar views. The net effect of this, on the display, is that a
single object may appear as two separate entities when in reality, it is one continuous
object. See Submerged Bridge: A Closer Perspective and the Submerged Bridge graphics
on the next page for examples of this.
Water Column
Bait Ball
Rock
Creek Bed
Tree
Bank
Stump
Fish
Side Imaging Representation