The Magazine for Underwater Professionals
USA-based high-resolution sonar imaging systems specialist EdgeTech reports the delivery of a new sonar system for the high-speed MMT Sweden Surveyor Interceptor ROV.
The system is a dual frequency sidescan sonar operating at 600kHz/1600kHz combined with a sub-bottom profiler operating at 1kHz to 10kHz.
“The uniqueness comes in the custom multi-pulse (MP) and dynamically focused (DF) capabilities of the sidescan sonar,” said EdgeTech. “To ensure customers can take full advantage of the high-speed capabilities of the Surveyor Interceptor, the sonar needed to be able to produce high quality images while also operating at higher speeds than typically seen with work-class or inspection-class ROVs. The EdgeTech MP and DF technology perfectly fits the application.”
Conventional sidescan sonar systems are limited in transmit-receive cycle times by the sound propagation velocity of 1500 metres per second. Following the transmit pulse, the sonar system has to wait for reception of the echo data from the farthest range before the cycle can repeat. This restriction results in ping rates that are adversely affected by range, and can severely limit the speed of the sidescan sonar, according to EdgeTech.
“With the ability place more than one sonar ping in the water simultaneously, EdgeTech sidescan sonars break this sound speed barrier,” explained the company. “EdgeTech’s multi-ping sidescan sonar can transmit pulses during normal reception, without any cross pulse interference. This technique allows sonar ping repetition rates greater than those achieved with standard sonar.”
The firm added: “Dynamically focused technology is a way to achieve higher resolution imagery at longer ranges when compared to conventional sidescan sonar systems. Dynamic focusing is achieved through a virtual curvature and focusing of the arrays using software algorithms in association with a multi-segmented array consisting of a number of short linear elements. The effective result is higher resolution at longer ranges.”
EdgeTech’s MP and DF technology onboard the high-speed MMT Surveyor Interceptor ROV was delivered in a compact 2205 AUV/ROV-based sonar package. The technology is also available in towed configurations.
UK-based Tritech has been selected as the preferred supplier for sonar and acoustic positioning on board Saab Seaeye, UK, Falcon ROVs for Försvarets Materielverk, (FMV), the Swedish Defence Materiel Administration.
The ten ROV systems will be deployed for seabed surveys, inspections, light underwater work and recovery of objects and encompass a full suite of Tritech sonars including Gemini multibeam imager, Micron mechanical scanning sonar, PA500 altimeter and MicronNav USBL.
The selection of Tritech’s sonars follows demonstrations at Portland Harbour, Dorset, UK, where Saab Seaeye invited Tritech to mine countermeasure (MCM) demos. Here Tritech highlighted the capabilities of its underwater sensors and data acquisition and logging software, Seanet Pro, to assist the ROV pilot to navigate, locate and position to target and subsequently obtain visual confirmation of the target.
Chris Lade, defence sales manager at Saab Seaeye, said: “The team tasked with military operations requires a reliable sonar and acoustic tracking system to reduce operation time and cost. Tritech has continually supported Saab Seaeye with product and engineering support and following our pan-technology demonstration day at Portland, the Tritech sensor suite was found to be the best fit for this project due to its continuous real-time feedback, software control and ultimate reliability in the field.”
Mike Broadbent, Tritech sales manager, said: “The supply of our equipment to Saab Seaeye to satisfy this naval order highlights the confidence in our kit for military operations. We were delighted to be part of Saab Seaeye’s leading-edge development in MCM.”
MacArtney, Denmark, reports that, spearheaded by oceanographic experts from its German operation, MBT GmbH, it has delivered the full connectivity package for the innovative UFO (Underwater Fish Observatory), which was deployed in the North Sea late last year.
Realised through successful cooperation between the Thünen Institute of Sea Fisheries in Hamburg, Germany, the University of Applied Sciences in Kiel, Germany, and MBT, the UFO project marks a noticeable leap forward in fish monitoring technology and methodology, said a MacArtney spokesman.
“Basically, the UFO project provides an underwater observatory for the quantitative determination of fish stocks,” explained the spokesman. “Specifically, the UFO project is based on a rugged subsea lander boasting multiple oceanographic sensors and high-tech equipment. The purpose of this lander is to measure fish stocks by means of stationary monitoring with optical and acoustic technology. The novel approach provided by the UFO project is the purely observational and therefore non-invasive method applied. The successful application of this method is intended to significantly reduce cost and labour-intensive sampling catches.”
The UFO system observes fish using a combination of high-resolution sonar system imagery and footage captured with extremely light-sensitive stereo installed underwater cameras. Together, these systems automatically register the passing fish, without having any influence on fish stocks in the area examined. Further sensor systems on board the UFO lander include a turbidity sensor, a current meter, conductivity and pressure sensors and a receiver for fish tag signals. The combination of the camera, sonar and sensor data provides comprehensive information about fish characteristics as well as the detection of fish stocks.
“In order to ensure the best performance and results when it comes to interfacing the sensors and transmitting the gathered data back to the surface, the UFO project relies on a complete connectivity package from MacArtney,” the spokesman said. “All sensors are interfaced by SubConn connectors and MacArtney cable assemblies hooked up to a MacArtney NEXUS MK C multiplexer, which is, in turn, linked to topside via a modified MacArtney TrustLink chamber termination and a 500-metre armoured fibre optic signal and power cable.”
Beyond providing signal and data infrastructure between sensors, topside and seabed, the MacArtney connectivity system also allows operators to trigger a pop-up recovery buoy to be deployed after the operational phase, the spokesman added.
In late 2014, the lander was installed at around 300 metres distance from the FINO3 platform, one of three fixed research platforms in the North Sea and Baltic Sea. Operated by the Research and Development Centre of the University of Applied Sciences, Kiel, the site is located about 80 kilometres west of Sylt and is surrounded by a protective zone where fishing vessel entry is banned.
The UFO was installed by divers. Afterwards, the cable was laid to the FINO3 platform and the topside end of the cable was inserted into the platform tower and connected to a junction box. A first operational test proved successful and provided the first snap shots of a school of fish captured within the live image from the cameras.
Incat Crowther, Australia, reports the delivery of Sistac Victoria, a purpose-built RINA-classed, DP2 monohull dive support vessel intended for service in Brazilian offshore waters. The vessel was designed by Incat Crowther in collaboration with the vessel’s builder, SeaSafe Barcos Manufacturados in Angra dos Reis, Brazil, for Sistac Sistemas De Acesso, Brazil.
The Sistac Victoria’s aft working deck includes multiple A-frame assemblies with integrated winches for ROV and dive bell launching and retrieving as well as a knuckle boom crane for handling deck gear and a small rescue/service vessel. The aft deck also features a lower platform at the stern to facilitate direct access to the sea by diving personnel and a dive shop and dive control centre.
The interior of the main deck house includes an emergency generator space, a decompression chamber, office, TV/entertainment room, meeting room, lunch room, galley and three single-berth cabins for senior personnel. Below decks are accommodations for the 33 crew and dive personnel.
The wheelhouse features forward and aft facing controls, a refreshment centre and two ROV control stations.
A large deck ahead of the wheelhouse provides a landing area complying with Petrobras requirements for accommodating a crane-loaded man-riding basket, and for carriage and delivery of supplies and cargo.
Romica Engineering Ltd (REL), UK, reports it has signed a contract with the UK’s National Oceanography Centre (NOC) to provide four umbilical winches, “allowing the NOC to facilitate seismic and towed ocean bottom instrument operations at sea with self-contained systems providing the ability to move between platforms of opportunity as required”.
The company said the 100-metre capacity winch systems are multi-purpose; they will be used for the deployment of both Bolt and GI airgun systems and also available for other large diameter umbilical deployments. As the winches are self-contained, enclosed within suitable ‘bump frames’ to prevent damage in transit and fit in a standard 20-foot (six-metre) soft top ISO container, they can be easily ‘cross decked’ between NOC vessels, the firm added.
Bob Turner, REL’s managing director, said: “We are delighted that the NOC has once again selected Romica as a winch system supplier to support its umbilical winch requirements. This contract for the supply of four umbilical winches complete with remote control allows the NOC to utilise the systems on international partnership vessels as well as those of other NERC (UK Natural Environment Research Council) organisations such as British Antarctic Survey, which is currently in the process of purchasing of a new research ship.”
OceanServer Technology, USA, reports it has delivered an Iver AUV for the MODUM project supported under the NATO Science for Peace and Security (SPS) programme.
The purpose of the MODUM is to move “towards the monitoring of dumped munitions threats in the Baltic Sea”. The goal of the project is to establish a cost-effective, research-based monitoring network using underwater vehicles to enhance understanding about dumped munitions in the Baltic Sea which pose both environmental and human security threats.
The Iver AUV is equipped with high-resolution sidescan sonar, a magnetometer and a full suite of environmental sensors utilising the YSI, USA, 6600 sonde.
“This combination of sensors enables the AUV to identify likely munitions and take geo-registered environmental readings in close proximity to the targets,” said OceanServer. “The vehicle will primarily be operated out of the Institute of Oceanology of the Polish Academy of Sciences in Sopot, Poland.”
Dumped chemical weapons pose an environmental and security hazard in the Baltic Sea region. The Iver AUV should help determine the location of munitions (many of which are unknown) and allow for environmental impacts originating from corroded munitions to be continuously assessed.
Following the first few deployments of the AUV, NATO country project director Jacek Beldowski said: “The vehicle proved to be of use in an offshore environment, even during 1.5-metre waves, operating satisfactorily down to 120 metres depth. The recovery cocoon demonstrated successful operation even with ships with six metres distance to the water.”