5. CALIBRATION
5-2
5.2.2
How to bind the standard sphere
Bind the standard sphere with the fishing line as
shown in the figure below. The length on the side
of the triangle is as follows.
• 38.1 mm diameter standard sphere: L=30 mm
• 47.625 mm diameter standard sphere: L=37
mm
5.2.3
How to select the measurement area
Select the measurement area, considering the following points. An unsuitable region
will affect data accuracy.
The most suitable time to do the calibration is when the tide subsides at daytime. The
lull in the morning and early-evening are also suitable. Nighttime is not suitable be-
cause plankton rise to the surface and the light from the ship attracts fish.
• Do the measurement Inside a bay with no waves, winds, or tidal current.
• The bottom should be comparatively flat, and the depth at least 30 m (ideally, more
than 50 m).
• The water should be transparent (less living objects).
• The area should be free of other vessels.
• Select an area free of fishing facilities.
Between steps (f) and (g), put the calibration ball into the “basket”
and confirm that there is no slack in all lines. Also, pull on the
calibration ball to confirm that it is tightly fastened.
Explanatory note
(a)
(b)
(c)
(d)
(f)
(g)
(e)
L
1
2
3
4
5
1
2
3
1
2
3
4
5
6
7
8
9
1
2
3
4
5
6
7
10
8
9
1
2
3
4
5
6
11
10
8
9
1
2
3
4
5
6
7
7
1
2
3
4
5
6
7
8
9
10
11
NOTICE
Do not do the calibration in an area where
there are many fish.
Too many fish can decrease data accuracy.
Also, avoid areas known for puffer fish, as they
can cut fishing lines.
