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CHAPTER 1. GENERAL
The Furuno model DS-30 Doppler Sonar provides accurate measurement of the fore/aft and
port/starboard speed of vessels. It mainly consists of display unit, processor unit, junction box,
transceiver unit and transducer (hull unit).
NOTICE
Do not apply paint, anti-corrosive sealant
or contact spray to coating or plastic
parts of the equipment.
Those items contain organic solvents that
can damage coating and plastic parts,
especially plastic connectors.
1.1. Selecting Mounting Location
1.1.1 Transducer (Hull Unit)
The performance of the DS-30 is directly related to the mounting location of the transducer.
Especially air bubbles and turbulence caused by movement of the ship and interference from other
acoustic equipment seriously degrade performance. The mounting location should, therefore, be
determined carefully, keeping the following factors in mind.
1) Air Bubbles
Since the transducer of the DS-30 is installed flush with the ship’s hull bottom, it is susceptible to
air bubbles which flow below the hull bottom. Select a location where air bubbles created at ship’s
bow do not go down to the mounting location. When the ship has a bulbous bow, install the
transducer in it or just behind it. However, when the ship makes a voyage in high latitude area
breaking through ice flows, avoid the location where broken ice flows may strike the location.
The DS-30 is used not only for ocean going navigation but also for docking to loading/unloading
facilities, at which the bow and side thrusters are used. The transducer should be separated at least
4 or 5 meters from them.
NOTE: In extremely shallow harbors with soft bottom, whirls created by ship’s movement
cause air bubbles and also bottom materials to be stirred, which may make the
use of DS-30 impossible.
2) Cavitation
Dents on ship’s bottom cause whirls behind them and may sometimes cause cavitation which
adversely affects the performance of the transducer, especially when the ship moves at a high
speed.
The welded portion between the transducer casing and the ship’s hull should therefore be finished
as smooth as possible.