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Quick Disconnect Mount: The Quick Disconnect Mounting system is an exclusive
Humminbird® feature that permits the unit to be easily removed from the mounting base by
pressing a release button, and re-installed by simply snapping it back into place. All cable
connections are made when installing, so that no separate wiring connections are required.
Additionally, the mount offers 90° tilt and 360° swivel capability to adjust the viewing angle
of the unit as you move about the boat.
Real Time Sonar: Real Time Sonar is a Humminbird® technology that delivers ultra-fast sonar
transmitter/receiver operation and results in a more detailed instantaneous view of what is under
the boat. The Real Time Sonar window is a vertical band at the right side of the display that shows
the instantaneous sonar return from the transducer at a particular instant. The RTS® Window
menu option permits the user to adjust the window to show the full sonar signal return, or just a
narrower band that indicates intensity using grayscale. Real Time Sonar relies on very fast Sonar
Update Rate (Ping Speed). See Sonar Update Rate.
Receiver: See Transmitter.
Second Return: The Second Return is a term that describes the appearance of a second sonar
return below the primary sonar return (bottom contour) at exactly twice the true depth. The
second return is caused by the same sonar energy bouncing off the bottom once, rebounding to
the water surface and then traveling back down to the bottom to be reflected again. Second
returns are more common in shallow water and over hard bottoms; it is actually possible to see a
third sonar return under some circumstances. The second return provides useful information to
help determine bottom hardness, as areas with harder bottoms will generally create a second
return. The second return can be used as a guide to set Sensitivity when in shallower water.
Sensitivity: Sensitivity is a user feature that adjusts the sensitivity of the sonar system to show
more or less detail in the water. Higher sensitivities are often preferred, however, when the water
contains debris (silt, storm debris, etc.) and it can be difficult to pick out targets. Conversely, if
sensitivity is set too low, relevant targets may be missed.
SONAR: SONAR is the acronym for SOund and NAvigation Ranging. Sonar technology uses
precision sound bursts transmitted underwater to determine the distance and other attributes of
objects in the water. Distance can be determined because the speed of sound in water is constant,
and the time for the signal to return is measured. Sound also travels very quickly underwater,
making sonar a responsive, cost-effective tool. Sonar is the basic technology behind all
recreational and commercial fishfinding and depthfinding devices.
Sonar Echo Enhancement: Sonar Echo Enhancement is a Humminbird® feature that describes the
high degree of sonar sensitivity achieved through a combination of transmitter/receiver and
software algorithms. The result of Sonar Echo Enhancement is to display virtually everything in
the water that is of interest to the angler, including bait fish, game fish, thermoclines, weed beds,
subtle structure, and more.
Sonar Update Rate: Sonar Update Rate is the number of times per second that the
transmitter/receiver sends and receives sonar signals. A very fast sonar update rate collects more
information and provides a more detailed image of the bottom, fish and structure. Many
Humminbird® units operate at up to 40 times per second when in single frequency operation.
Due to the limitation of the speed of sound in water, the update rate begins to slow as depth
increases to deeper than 50 feet. In very shallow water (less than 10 feet), however, update rates
as much as 60 times per second can be achieved.
Speed: Speed is the rate at which the boat moves through the water. Boat speed can be measured
as Speed Over Ground or Speed Through Water. Speed Over Ground is provided by GPS, and is the
measurement of the boats progress across a given distance. Speed Through Water is provided by
a speed paddlewheel, and is the measurement of the flow past the boat, which may vary
depending on current speed and direction. Speed Through Water is most critical for anglers using
downriggers, as it impacts the running depth of the down riggers. Speed Over Ground is optimal
for navigation, as accurate destination times can be derived from this measurement.
Humminbird® products allow for input and display of both sources.
Structure: Structure is a general term for objects on the bottom that present a discontinuity and
are a likely attractor for fish. This includes bottom contour features (drop-offs, humps, and holes),
standing structure (stumps, timbers, brush piles) and a wide range of other potential objects
(sunken boats, reefs). Humminbird® units excel at showing structure with great detail over a
wider area due to unique sonar configurations developed for the angler.
Structure ID®: Structure ID® is a Humminbird® feature that describes the traditional grayscale
method of presenting sonar information. See Grayscale.
Surface Clutter: Surface Clutter is a phenomenon where sonar returns are reflected off of tiny
objects near the surface of the water, including algae and even air bubbles. Typically, saltwater
environments have significantly greater surface clutter than freshwater due to continuous wind
and wave action that causes aeration at the surface. The Surface Clutter menu provides manual
control to bias the default settings under extreme conditions.
Target Separation: Target Separation is the measurement of minimum distance that a
fishfinder needs to be able to recognize two very close objects as two distinct targets (i.e. two
fish hanging very close, or a fish hanging very close to structure). Humminbird® findfinders
provide a very good 2 1/2 inches of target separation in shallower than 100 feet of depth.
Target separation decreases as depth increases due to the need for longer Pulse Width to
achieve greater depth. See Pulse Width.
Thermoclines: Thermoclines are water layer(s) of distinctly different temperatures that create a
sonar reflection due to the density of the differing water temperatures. Typically a thermocline
will appear as a continuous band across the display at some distance above the bottom contour.
Thermoclines are of interest to anglers because fish will suspend above or below the thermocline
as they seek the optimum temperature and oxygen levels.
