Airmar Acoustic Deterrent System—dB Plus II™ - Manual (Page 5)

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The effective range of the projectors is reduced by underwater obstructions such as fouled nets or the
biomass of a school of fish. Therefore, it is necessary to completely surround the entire pen system and, in
effect, create an acoustic barrier around the outer perimeter (see Figure 2). The range of each projector
limits the coverage of a complete 4 projector system to an area not exceeding 3,000 square meters
(33,000 sq. ft.).
Projector Installation
The standard dB Plus II

system has four underwater sound projectors. Each projector has 60m (200') of
high visibility, abrasion resistant cable with a corrosion resistant, weatherproof connector. It should be
noted that the projector connectors and the power supply connectors are of reverse gender to prevent
incorrect installation. The projectors are positioned at the outer edge of the pen walkways but not in the
path of boat traffic and propellers. If the transmitter has been placed away from the center of the
installation, it may have been necessary to add extension cables to the projector cables. Airmar’s unique
design allows adding extensions with very little loss of sound output.
Whenever possible, projector cables should be laid underneath walkways. Areas prone to moving and
swaying, such as gangplanks, should be avoided, as they could chafe or cut the cable.
Each projector is equipped with an eyelet to allow it to be suspended from a line approximately 1m (3')
below the bottom of the pen.
Do not suspend a projector by its power cable since this may sever internal
connections. Below the waterline, the cable must be tie-wrapped to the supporting line and free of any
slack or loops. Each projector should be suspended at the outer most edge of the walkway in order to avoid
fouling with other lines or netting.
Never suspend a projector between or inside pens.
Transmitter Installation
The transmitter must be mounted at least 1m (3') above any decking and, preferably, protected from the
rain. Placing it directly under solar panels is ideal. Although the transmitter is waterproof, this added
protection will prolong its life.
WARNING : Under no circumstances, should unauthorized personnel remove the transmitter cover. Doing
so may result in electrical shock. Unauthorized removal of the transmitter cover breaks the factory seal and
voids the warranty.
Figure 2. Projector coverage
100 m (330')
30 m (100')
40 m (133')
typical radius
sound pattern
around pens
projector 1
projector 4
projector 2
projector 3
60m (200')