VEMCO - VR2 Manual
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4
Deployment
How a VR2 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 VR2
receivers are explained here. The common method for attaching a VR2 to a mooring line is also given.
4.1
Deployment Facts/Tips
4.1.1
Mooring
VR2 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 VR2 should be positioned above
the floor such that it has an unobstructed “view” of tagged animals within their expected acoustic range.
Ensure the VR2’s hydrophone is unblocked (e.g. do not position an air filled buoy directly above the
hydrophone) and free of any significant biofouling. In high flow locations, you might consider using hydro
dynamically shaped buoys and low profile anchors.
For the best horizontal range, mount the VR2 receiver in a
vertical position. If the VR2 is deployed close to the bottom,
mount the VR2 with the hydrophone pointing up to the
surface. If the VR2 is deployed close to the surface in deep
water, you could position the VR2 so the hydrophone is
pointing down. Conduct range testing to determine the
optimum orientation.
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 VR2 receiver. It can be used to cover the entire receiver case or
just the Probe Hole and does not leave a glue residue when it’s removed. Another option is to use an
antifouling paint, such as Interlux Micron CSC.
CAUTION:
The hydrophone must
be kept
free of mooring lines
and obstructions
. Objects
around the hydrophone will
adversely affect the detection
range of the VR2 receiver.
Never cover the Status Light (LED)/Release Valve.
The release valve
must
be able to pop open if needed
and must not be blocked by tape or paint.
See the Gate Design