Fish Indications - Raymarine hsb2 PLUS Owner's Handbook Manual

4-2
The Fishfinder provides a White Line feature which helps to distinguish
between the bottom and fish (or other items such as weed) that are close to the
bottom.

Fish Indications

When the Fishfinder detects a fish, it displays an arch-shaped mark. In
general, a larger arch indicates a larger fish, though this rule is not always true.
Let's say that there are two fish of the same size: one is close to the surface, the
other is near the bottom. The fish which is close to the surface has a larger arch
because, being closer, more sound waves get returned to the Fishfinder.
To display the depth of the fish, switch on the TARGET DEPTH ID from the
SONAR SET UP menu, as described in Section 7.4, Fishfinder Set Up
Parameters.
The sound waves are actually reflected by the swim bladder near the center of
the fish, not by the body of the fish. The size of this swim bladder is different
for different kinds of fish and this can affect the size of fish arches on the
image. A fish with a large swim bladder produces a large fish arch, while a fish
with a small one produces a small arch. Several arches together show a school
of fish. Figure Figure 4-1 illustrates some typical fish indications.
50 kHz
Figure 4-1:
An arch-shaped image indicates a fish.
The same fish appears differently when shown by the
50 kHz or 200 kHz transducer beams.
200 kHz
A shallow arch is generated when the the boat is
moving slowly.
This indicates a group of small fish.
A fish moving under a stopped boat shows as a line.
When the boat is moving very fast, a fish appears as
two parallel lines.
Fish Indications
hsb Plus Series Fishfinders
2
D5017-2