GENERAL OPERATION
With the power supply connected to the instrument,
turn the "gain" control to the "ON" position.
Yellow LED will flash at "0" on the dial. Select
shallow water range and turn "gain" control in a
clockwise direction until a second (echo) indication
appears on the dial. This indicates the depth otwater
beneath the face of the transducer. If the "gain"
control is advanced more than is necessary, multiple
echoes of the true depth will appear. This setting is
too high and should be reduced until only the first
echo is visible. This will improve clarity of reading
and conserve battery power.
The efficient performance of all echo sounders
depends on the nature of the sea bed. For instance, a
hard, rocky or firm sand sea bed will reflect back
ultra-sonic sound waves extremely well. The return
echo from a sea bed of this type will be shown as a
firm flash on the dial at the appropriate depth. On the
other hand, deep mud or large amounts of kelp will
give a weaker reflection and produce a wider, more.
indeterminate flash.
With practice it is therefore
possible to ascertain not only the actual depth, but
also the type of sea bed. To locate fish, advance the
"gain" beyond the normal setting for depth
i
ndication only. Fish will then be indicated by
random flashes at their appropriate depth. It should
be noted that an echo return from fish depends on the
size of the air sac and varies greatly with different
types of fish.
DEPTH ALARM OPERATION
The Seafarer 5 is fitted with an audio alarm which will
give a warning when the depth of water below the
transducer falls below a pre-set level. This is adjusted
by the "ALARM" control and is variable from 0.8
metres (2.7ft) to a nominal maximum of 30 nictrcs
(16 fathoms).
When the alarm facility is not
required, the control should be set to the "MIN"
position. To set the depth at which the alarm is to
operate, turn the "ALARM" control in a clockwise
direction. A yellow flashing LED will appear on the
dial face. Continue to rotate the "ALARM" control
until the forward edge of this LED indicator is
aligned with the required depth calibration on the
dial,
If the depth of water below the transducer falls
beyond the alarm setting, then the alarm will sound.
This can then only he silenced by sailing into deeper
water or, by turning the "ALARM" control in an
anti-clockwise direction.
CAUTION-If the transducer is mounted in a
vessel
which has projections below the transducer
(keel or twin bilge keels etc) then the alarm setting
must take into account this additional depth, if
grounding is to be avoided.
8
DIGITAL REPEAT METER
(
Optional Extra)
A digital repeat meter is available as an optional
extra. This instrument is suitable for use with
Seafarer 5 or Seafarer 7(X) echo sounders. The
meters are single range and can be supplied
calibrated to read in feet or metres. The "metric"
model reads from 0.8 metres to 119.9 metres and the
"feet" model from 2.7 feet to 359.9
feet.
The
calibration of the repeat meter is independant of the
echo sounder and it will continue to read in its factory
set units, whichever echo sounder model (foot/
fathom or metric) it is used with. Depth is indicated
on a four digit liquid crystal display which is fitted
with red, LED edge lighting for night use.
INSTALLATION
The repeat meter may he flush mounted in the
cockpit or other suitable position for use by the
Helmsman or Navigator. It requires only a single
hole fixing of 87mm (3.4in) diameter. Whilst the
front face of the meter is weather-proofed, a suitable
sealing compound should be used to ensure a
watertight seal between the bulkhead anti the meter
flange.
Inter-connection between the repeat meter and
the echo sounder is via a 4-core screened
cable of 6m
length. If required, this may be extended by using a
terminal block and extra cable of the same (or
very
similar) type. The scr'cn must be disconnected and
separated from the wire and solder tag to which it is
connected. The screen and four wires are then
connected via the terminal block to the extension
cable. The end of the extension cable to be
connected to the echo sounder must be made up with
the screen and wire connected together at the solder
tag.
However, care must be taken to ensure that the
joint is fully protected against ingress of water. The
cable is an integral part of the repeat meter and is
supplied with it. To connect to the instrument,
remove the battery compartment cover and make a
hole in the repeat meter cable entry grommet.
Thread the cable through the grommet and connect
each lead to the appropriate terminal following the
diagram supplied. Finally, replace battery
compartment cover. If display illumination is
required, then a 12 volt D.C. (ships supply) should
be connected to the terminals at the rear of the
meter. For 24 volt systems, connect a resistor (180
ohm 1 watt) in series with the supply. To provide a
vartable level of illumination, a potentiometer (1
Kohm) should be fitted in series with the supply. In
which case the 180 ohm resistor should he omitted.
REPEAT METER OPERATION
The repeat meter will start to operate as soon as the
Echo Sounder is switched on. However. if the "olain"
control is set too low, colon in the middle of the
