Humminbird 987C SI COMBO manual Side Imaging Technology HOW IT Works, Side Imaging Representation

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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.

•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.

Side Imaging Representation

Creek Bed Rock Bait Ball Fish Tree Stump Bank

Water Column

SIDE IMAGING: ON THE WATER INTERPRETATION

Use the following side imaging examples to help you interpret the side imaging 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 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 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.

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