VEMCO - VR2Tx Manual
15 March
2019
28
4
Deployment
How a VR2Tx is deployed is driven by the environment it is being deployed in and the type of study being
performed. Some important points to keep in mind when designing a deployment plan for your VR2Tx
receivers are explained here. The common method for attaching a VR2Tx to a mooring line is also given,
along with the dimensions of the VR2Tx cases.
4.1
Deployment Facts/Tips
4.1.1
Mooring
VR2Tx receivers are moored in many configurations often reflecting the bathymetry and
oceanographic/weather conditions. A simple mooring design generally works well. However, in rougher
conditions, heavier weights and mooring lines are usually required. If a bottom mooring is desired, the
VR2Tx should be positioned above the floor such that it has an unobstructed “view” of tagged animals within
their expected acoustic range. Ensure the VR2Tx’s hydrophone is unblocked (e.g. do not position an air filled
buoy directly above the hydrophone) and free of any
biofouling. In high flow locations, you may consider using
hydro dynamically shaped buoys and low profile anchors.
For the best horizontal range, mount the VR2Tx receiver in
a vertical position. Always mount the VR2Tx with the
hydrophone pointing up to the surface for better acoustic
communication with the VR100.
4.1.2
Spacing
Receiver spacing is generally determined based on range testing and historical acoustic data. Our position is
that you should try to space receivers such that you achieve good detection probability in most or all weather
conditions. It is not always necessary to have 100% coverage if you have several other locations where you
know the animals will be passing through. However, if you wish to accurately
quantify the passing of animals through receiver locations then you should
strive for 100% detection probability. Typical spacing is usually between 100
and 1,000 meters.
4.1.3
Biofouling
Some customers use a rubber shrink tape, such as DAFLEX ST250 Cold Shrink Tape,
available from Digikey (W211-ND), to prevent biofouling on the VR2Tx receiver. It can be
used to cover the receiver body (Do not cover the hydrophone or the release valve) and does
not leave a glue residue when removed. Another option is to use an antifouling paint, such as
Interlux Micron CSC.
When using antifouling paint, consult the manufacturer’s safety
data sheet and follow their recommended handling procedure (safety glasses, gloves, etc.)
CAUTION:
The hydrophone must
be kept
free of mooring lines
and obstructions
. Objects
around the hydrophone will
adversely affect the detection
range of the VR2Tx receiver.
See the Gate Design
Never cover the Status Light/Release Valve.
The release valve
must
be able to pop open if needed
and must not be blocked by tape or paint.
NOTE:
Keep the
hydrophone
uncovered to
prevent
acoustic
dampening.
