Filter
Top Products
120
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® fishfinders
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.