Simrad ER60 - REV B Operator's Manual page 34

Simrad ER60 Operator manual
Figure 2 Sound
absorption
26
Sound absorption (dB/km)
60
from: Francois & Garrison, JASA, December 1982
o
10 C
50 200 m depth
pH = 8
40
30
20
10
0
0 25 50
(CD468 / GIF / WMF)
3 Pull a rope beneath the hull from one side of the vessel to
the other.
4 Anchor the vessel.
It is desirable to work in water as deep as possible, consistent
with maintaining a stable platform. Both bow and stern
anchoring or mooring is recommended.
If the vessel is anchored or moored only fore or aft, the wind
will cause it to drift sideways. If the current then attacks with a
different angle, it will make a bad situation even worse. If the
vessel is allowed to move sideways, or if the current runs
abeam, this will normally give larger variations in the echo
sounder performance. This results in poor and not reliable
calibration accuracy.
Winches
We recommend the use of winches to guide and steer the lines to
the sphere for its centering in the echo sounder beam. These
winches must be mounted to the deck railing in accordance with
detailed ship drawings.
1 Place the first winch in the transverse plane of the vessel
running through the transducer.
- If the transducer is mounted on one side of the keel,
place the first winch on the opposite side of the vessel.
75 100 125
Frequency (kHz)
150 175 200
850-164692 / Rev.B