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Measuring Fish School Speed
To ensure a good haul, it is important to estimate the direction
and speed of the fish school before shooting the net. You can do
this with the FISH key. If the tidal current data is used together
with fish speed data, you can determine the timing of the net
shooting more efficiently. This function requires speed and head-
ing inputs.
1. Place the trackball mark on the center of a fish school, and
then press the FISH key. The latest fish mark (
) appears on
the fish school.
2. Wait 1 to 2 minutes.
3. Place the trackball mark on the same fish school selected in
step 1 and press the FISH key. The latest fish mark (
) ap-
pears on the target and the 2nd latest fish mark (
) appears
on the location selected at step 1. At the bottom left corner of
the screen, the distance between the two fish marks, and fish
school course and speed appear.
4. If you want to delete fish marks and fish speed marks, open
data setting window, select DELETE MK and then press the
FISH key.
Latest fish
mark
Latest
fish mark
Fish
movement
Figure 7-9 How to measure fish speed
Note 1: Movement is calculated using ship’s speed and bearing
inputs. Accordingly, pitching and rolling may affect the calcula-
tion. For better results, try the procedure two or three times to
verify reliability.
Note 2: The time and distance between pressings of the FISH
key should be as long as possible to increase accuracy of mea-
surement. For more accurate measurement repeat the procedure
two or three times.