Hull Mount; Sea Chest; Over The Side; Figure 7: Transducer Mounted Over The Side - Teledyne Echotrac E20 Operator's Manual

INSTALLATION
4.3.2

Hull Mount

Streamlined transducers mounted directly to the outside of the hull or transducers fitted into
streamlined fairings welded or otherwise attached to the outside of the hull often make for excellent
installations. The advantage is that the radiating face of the transducer is generally below the bubble
stream in clear water and no acoustic window or transducer tank creates reverberation.
This type of installation requires a stuffing tube to be installed in the hull in order to allow the
transducer cable to penetrate the hull.
4.3.3

Sea Chest

In a sea chest mount, a fluid-filled enclosure in the hull of the vessel is large enough to contain the
entire transducer. The outer hull is removed in the area of the chest and replaced with an acoustically
clear "window" which is mounted flush with the hull.
Depending on construction, material selected for the acoustic window, and draft of the vessel, access
to the transducer can often be gained from inside the hull without putting the vessel in dry dock.
In most installations, a water-filled standpipe is incorporated into the sea chest design in order to
provide hydrostatic pressure equalization. Transducer cables generally leave these assemblies
through stuffing tubes, which maintain the watertight integrity of the chest.
4.3.4

Over the Side

This type of mount is frequently constructed from a length of pipe. This fixture should be sized to
position the transducer well below the waterline and the pipe then fixed to a sturdy support on the
vessel. Lines are usually attached to the transducer pipe and tied off fore and aft in order to maintain
a stable, horizontal transducer attitude.
Ensure that the transducer is mounted sufficiently deep so that it does not break the surface
during vessel roll motions
Vibration and oscillation will become evident, if the transducer is not rigidly mounted. To
minimize the unsupported length, place a support as close to the waterline as possible
Care should be taken to assure adequate protection for the transducer cable,
particularly at the point where the cable leaves the transducer body.
Echotrac E20 Operator's Manual8
Version 8
. This may mean to a depth greater than 0.3m.

Figure 7: Transducer mounted over the side

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Uncontrolled Technology Subject to Restrictions Contained on the Cover Page.
November 25, 2020