Proliferation SeaSonde Coastal Current-Mapping Radars

HF interference to improve coverage performance
For several decades while coastal HF current-mapping radars were under development, they radiated rarely and only for a few weeks at a time. Now 120 commercial SeaSonde units have been sold and seventy operate continuously in permanent locations. Their numbers are presently increasing at a rate of about 35 per year and they are used for a variety of maritime purposes. Although emitting only 50 watts of power they can map currents to 200km on the lower frequencies; these signals may also travel half way around the world, thanks to overhead reflecting ionospheric layers. After all, these same layers have... (read more)
2008-01-01 01:00:00

US Navy Hydrography Is Back!

The US Navy has a strong tradition in hydrography and has restated its commitment to this field by naming the Commander of the Naval Meteorology and Oceanography Command as the ‘Hydrographer of the Navy’. This was the culmination of significant focus and effort during the past decade by the US Navy’s meteorology and oceanography (METOC) community to improve not just hydrography, but all forms of environmental data collection. During the Cold War, METOC resources were concentrated on deep-water operations; hydrographic expertise, especially among Naval officers, was not maintained at a sufficient level to support the current naval doctrine of littoral... (read more)
2008-01-01 01:00:00

‘Killer’ AUV Sonar System

In January 2001, C&C Technologies (C&C), a company based in Lafayette (Louisiana, USA), introduced the first commercially successful autonomous underwater vehicle (AUV) to the offshore industry. The AUV’s survey sensor suite, which included an EdgeTech side-scan sonar and sub-bottom profiler, performed well in the Gulf of Mexico and Brazilian offshore environments. However, West Africa proved more challenging – particularly for the sub-bottom profiler. C&C soon began searching for alternative technologies to provide better sub-bottom profiler penetration and higher resolution side-scan sonar imaging.Jim Chance, C&C Technologies (USA) Art Kleiner, EdgeTech (USA)<P> Narrator: Fast forward to the early autumn of 2004… C&C... (read more)
2008-04-02 12:00:00

Automated Side-scan Data Analysis

Side-scan sonar is well accepted as a tool for detection and visualisation of underwater objects and is widely used in support of safety of navigation surveys. Although side-scan sonars produce excellent images, these images are often difficult and time-consuming to review and analyse. These images typically contain spurious features and artefacts due to acoustic phenomena, such as refraction, and bottom characteristics, such as sand waves that result in a large number of false contacts. This article describes a research and development effort at Science Applications International Corporation to develop and apply advanced processing techniques in bottom target detection and image... (read more)
2007-10-03 12:00:00

Quality ENC Production for HOs

The challenges facing the contractor
Hydrographic Offices (HOs) all over the world are going digital in their production environment. New shipboard equipment and improved display techniques embrace all the latest technologies in the interests of ensuring the Safety of Life at Sea (SOLAS). HOs increasingly seek to produce and distribute ENCs to standards specified in IHO Special Publication S57 (edition 3.1). The production and validation of ENC datasets to achieve these stringent quality requirements are outlined here. The International Maritime Organization (IMO) has amended SOLAS articles relating to carriage requirements for the use of ECDIS in certain types of vessels. When production is outsourced manufacturers... (read more)
2008-01-01 01:00:00

A New Solution for Subsea Metrology

Combination of Acoustics and Photogrammetry
Invariably, metrology is required at the critical stages of field development and the main goal for improvement is to reduce the time taken for acquiring data. The technique discussed offers significant improvements in terms of time and required equipment. Offshore Construction During offshore construction several structures have to be interconnected by means of spools or jumpers. In order to determine the dimensions and relative attitudes of the connections, surveyors deploy ROV-mounted instrumentation. IMCA S019 Guidance on Subsea Metrology offers the following combined accuracy guideline: 50mm to 150mm in X,Y and Z axis 0.5° to 1° for relative pitch, roll and heading.... (read more)
2014-09-02 11:57:09

Dredge Efficiency and Precise Positioning

Integrating Dredging and Hydrographic Techniques
Dredgers involved in mining for (precious) minerals and metals often work in an inland dredging pit. Dredgers float in a ‘wet environment’ where the surrounding water is used as transport medium. The fact that the minerals are mostly covered in various sediments is one of the biggest problems in mining them. This article describes some of the techniques used in these dredging operations and illustrates the importance of integrating techniques and information. Most minerals, like rutile and zirconia, are to be found on top of a layer of clay with the highest concentrations found closest to it. Pewter is mostly... (read more)
2008-01-01 01:00:00

Metocean Automatic Monitoring Stations in Malaysian Waters

Marine meteorological and oceanographic (metocean) data is required at all levels (e.g. planning and operations) of the Meteorological Department, the Naval Department, Ports or Harbours and the Oil and Gas Industry. The Meteorological Department of Malaysia has recently embarked on a Coastal and Port Automatic Meteorological and Oceanographic station network to support weather forecasting. This paper details functions and requirements for the development of this system. Marine meteorological and oceanographic technology has advanced a long way since the early days, from recording measurements on paper chart rolls to using solid-state memory, from simple wave staffs to satellite-transmitting wave directional buoys,... (read more)
2008-01-01 01:00:00

Trends and New Technology in the ROV Industry

New IMCA ROV Classifications and Applications Moving Towards Renewables
Over the past few years, the requirement for ROV support in the oil & gas sector has been hampered by the downturn in the sector. However, the continued investment in renewable energy has provided opportunities for manufacturers to continue their R&D projects to create the next generation of ROV systems. In view of this, the IMCA guidelines for the Safe and Efficient Operation of Remotely Operated Vehicles (IMCA R 004 Rev4) has been updated. The guidelines now include an expanded list of ROV classifications based upon the increased diversification of tasks performed by ROV systems around the globe. The revised... (read more)
2017-08-07 01:31:12

Low Cost or Cost Effective?

Managing cost through the fit for purpose principle
When asked to do an article on low cost hydrography within the offshore construction industry the first word that sprang to mind was 'cheap'. However 'cheap' might not be 'cost effective' which is, or at least is supposed to be, the decision driver. For a private Company to remain in business it is essential that any external service hired, provides value for money. Hence all survey services within the private sector can be considered 'lowest cost'. There is however another critical factor that shall be considered. If a service impacts on installation spread efficiency, it might be worthwhile to spend... (read more)
2008-01-01 01:00:00
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