User’s Manual INNOMAR Parametric Sub-Bottom Profilers / SESWIN 29
Innomar Technologie GmbH (2023-01) 29
3.2.4 Hull-Mount Transducer Installation / Mounting Frame
Innomar provides also transducers with optimized shock absorbers for hull-mounting.
For proper operation the transducer has to be fixed firmly and vertically because of the narrow
sound beam. The whole transducer must be covered by water all the time, even during rough
sea!
Protect the transducer cable against damages, take care on the bending radius.
Protect the transducer connector against damages and water to avoid corrosion.
The connector is not water proof! For transport and storage, the connector should be
sealed by the provided covers.
Protect the active area against damages (mechanics or chemicals).
Protect the active area against sunlight; UV-light may affect the materials used.
Do not use a transducer with damaged face or damaged cable!
The transducer face (active area) needs to be clean; no paint, oil or grease should be
on the active area of the transducer.
Use zinc anodes to prevent corrosion and replace these anodes in regular intervals.
To avoid biofouling, the transducer has to be coated using water-based anti-fouling (see
below)
Before starting usual dock work like sand blasting and painting the hull, protect the
transducer by putting covers on the transmitting area.
Before storage, rinse the transducer with fresh water and properly dry it.
Hull-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 entirely the desired acoustic signal.
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
transducer should not be the lowest point to avoid damages by boulders etc.
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 direction
(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.
Accordingly, flush installations are more easily troubled by aerated water than blisters and
gondolas that protrude from the hull.
Hull mounting: Installations flush with the hull will often cause problems due to aerated water
going below the transducer. Therefore, blisters or gondolas should be used for hull mounting.
Vibration / Reverberation: To avoid/reduce structure-borne noise and vibrations picked up by the
transducer, the INNOMAR mounting frame has integrated vibration isolators (shock absorbers).
The sea chest’s walls and ceiling should be lined by closed-cell foam (e.g. RS components 733-
6750) to reduce reverberation.
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. For the same reason, it is very important that the
hull area around the transducer face is as smooth and level as possible.
Transducer inclination: Transducers should be mounted horizontally (parallel to the water
surface) to ensure best system performance, especially for narrow- beam sub-bottom profilers
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