4. HOW TO DISTINGUISH THE NATURE OF BOTTOM
●
There are different natures of bottom such as rock, sand, mud or etc.
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2. HOW TO DISTINGUISH THE FISH SCHOOL
●
Important is comparison between display of fish school and catch
It is possible to distinguish the fish sort by display of fish school to some extent. But even if
fish sort is same, it’s form making school is different according to difference of fishing
ground and difference of time (day and night, four seasons, variation of current).
The important thing to distinguish the fish sort is to know the sort according to their fishing
ground or fishing period and to find the useful point on the display by comparing between
display of fish school and actual catch.
3. HOW TO DISTINGUISH THE FISH VOLUME
●
Fish volume can be distinguished by density and size of fish school
As the harder density the transmitted wave is reflected strongly, you can distinguish the
density of fish school according to the strength of reflected echo (that is, different color).
Normally we tend to think the larger fish school on the screen the most fish volume. But
when fish school are located at the shallow depth and the deep depth, fish school at the
deep depth is displayed bigger than at the shallow depth. Because the transmitted wave
spreads wider as it goes deeper and the reflected wave spreads wider as it goes shallower.
As this result, the deeper becomes the wider the width of fish school becomes on the
screen. The important thing to distinguish the fish volume is to judge it according to size of
fish school and the strength of reflected echo (color) while you keep “the deeper fish school
stays the bigger picture is displayed” in your mind.
Reflected
wave
Fish school A
Fish school B
Fish school A picture(shallow)
Fish school B picture(deep)
〈
Rock
〉
〈
Sand or Mud
〉
In case you distinguish the nature of bottom, you
judge from the thickness of bottom image and the
situation of second reflection. At the hard bottom like
rock, reflection of transmitted wave becomes strong
and bottom image becomes thick and the second
reflection becomes easily to appear. On the other
hand, at the soft bottom like sand or mud the reflection
becomes weak and bottom image becomes thin and
the second reflection becomes hard to appear.
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