16 User’s Manual Innomar SES Parametric Sub-bottom Profilers
16 Innomar Technologie GmbH (2020-09)
Pole-Mount transducer installation guidelines
Transducer depth: The upper water layers are filled with small air bubbles, especially in heavy
seas. Air bubbles absorb acoustic energy and may block the desired acoustic signal entirely.
Therefore, select a location as deep as possible for the transducers, where the water is less
aerated and you have a wider weather window. On the other hand, in shallow waters the trans-
ducer should not be the lowest point to avoid damages by boulders etc. Also avoid sound from
HF sidelobes hitting the ship’s hull, this would produce ghost echoes.
Transducer location: Select a location as far away as possible from sources of noise. For sub-
bottom profilers, usually the ship’s engine is the dominating noise source. Prefer locations in the
forward third of the vessel, which normally will provide less aerated water, less noise and less
turbulence. At small boats the best place is at the bow. Heave will be lowest mid-ship since no
angular components are added. Avoid locations near the ship’s aft because of noise (propeller
and engine) and aerated water.
Transducer Orientation: There is an arrow on top of the transducers pointing to forward direc-
tion (ship’s bow).
Bulbous bow: If the vessel has a pronounced bulbous bow, be aware that this will transport
aerated water down. Tunnel thrusters in the bow will also produce aerated water in heavy seas.
Objects protruding from the hull: Any objects protruding from the hull as well as holes and pipe
outlets generate turbulence and flow noise. Do not place the transducer in the vicinity of such
objects, and especially not close behind them.
Mounting pole: Be aware of the need for a stiff connection between transducer and motion sen-
sor. Also, be aware of limitations in vessel speed as well as weather window. Avoid small poles.
Reduce vibrations and bending of the pole by proper supports and ropes. Long poles may need
a rope below the ship’s keel.
Transducer inclination: Transducers should be mounted horizontally (parallel to the water sur-
face) to ensure best system performance, especially for narrow- beam sub-bottom profilers like
the INNOMAR systems. A small positive inclination (bow up, max. 0.5°) is acceptable in order to
ensure laminar water flow. Avoid negative inclination since this may cause turbulences.
Acoustic coupling / vibration: To avoid structure-borne noise going from the ship’s hull into the
transducer, the transducer has to be decoupled acoustically by using rubber or other damping
material. For pole-mounted transducers the steel-to-steel connections on the flange and on the
pole should be decoupled using elastic material like rubber, plastics or wood.
Electrical connection / grounding: To reduce noise caused by the mains generator the trans-
ducer’s housing should be electrically connected to the topside unit by an additional ground wire.
Prevent Corrosion: If the transducer is situated in water for a longer period of time, use zinc
anodes to prevent corrosion. Proper grounding is also essential.
Prevent bio-fouling: To reduce bio-fouling, pole-mounted transducers may be painted with an
approved water-based anti-fouling compound, see section on hull-mounted transducers below.
To Next Page
Loading...