MV Star Lysefjord
Vessel name
MV Star Lysefjord
Installation date
11-May-2024
Vessel type
General Cargo Ship
Application
Water Ballast Tank
STAR LYSEFJORD is a vessel built in 2014 and designed for commercial maritime operations. In May 2024, the vessel was at Chengxi Shipyard in China, where Shipsonic carried out an ultrasonic anti-fouling (USAF) installation on the vessel’s hull.
The USAF installation was designed as a test installation on the starboard side of Ballast Tank No. 5, comprising 10 × 80 W transducers installed on the vessel’s hull. Their positions were selected to account for the heavy internal structure of the ballast tank, including longitudinal stringers and athwartship frames, allowing the effect of structural attenuation on Sound Pressure Level (SPL) to be assessed.
Of the 10 transducers, 7 were welded, installed, and torqued into position afloat over one working day (Saturday 11 May) by a three-man welding team. The remaining 3 transducers were located below the vessel’s waterline and therefore could not be installed afloat. Their installation was deferred to the scheduled drydocking (expected 16–17 May), where they were to be installed by the ship’s crew and Chief Engineer. The Chief Engineer had prior experience, having installed eight transducers around the stern tube seal approximately one year earlier.
By the end of the visit, two of the newly installed transducers (positions 1 and 3, both located in the upper tank) were powered up and temporarily connected for testing.
The Ballast Tank No. 5 consisted of upper and lower sections with athwartship bulkheads spaced at approximately 3,200 mm or 2,400 mm intervals. Following inspection of the tank structure, the transducer layout was revised to position the transducers between the bulkheads and longitudinal stringers.
The installation was equipped with a UPS-backed power supply, as the selected power supply line was not connected to the vessel's emergency generator.
The transducers were installed in both the upper and lower sections of Ballast Tank No. 5. Seven of the ten transducers could be installed while the vessel was afloat, while the three lowest positions required the vessel to enter dry dock for installation.
The transducer flanges were welded to the hull and the transducers subsequently installed and torqued. The first transducers were also used to demonstrate the installation procedure to the vessel's Chief Engineer.
Sound Pressure Level measurements were taken for Transducers 1 and 2, with readings of 94–104 dB at the measurement position, 85–95 dB at a maximum distance of 1.5 m, and 82–92 dB behind the bulkhead/stringer or in the adjacent athwartship bulkhead, with the readings considered satisfactory.
The USAF installation provides ultrasonic anti-fouling protection for the hull area surrounding Ballast Tank No. 5, while the test arrangement also provides data on ultrasonic sound propagation through the vessel's internal structural elements.
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