Platform Decommissioning

Survey Opportunities to Optimise the Task
Oil and gas fields in the North Sea and elsewhere in the western world developed rapidly during the oil crisis of the seventies, when this commodity quadrupled in price. Now the first of approximately five hundred platforms have reached the end of their technical lifetime and need decommissioning. Heerema Marine Contractors has been involved in removing several complexes and here describes two cases, illuminating the survey aspects. Removal of facilities is very much an engineering challenge whereby safety and environmental issues play an important role. Historically, their installation involved surveyors who provided all precision positioning, dedicated equipment and proprietary software... (read more)
2007-05-09 12:00:00

Bed Mobility in the Weser Estuary Turbidity Zone

Mud in its unconsolidated, highly dynamic, fluid state may complicate problems arising from other detection difficulties in estimating water depth in estuarine channels with mobile bed deposits. This study presents new results on riverbed mobility in the turbidity reach of the Weser estuary based on datasets from an Innomar sediment echo sounder (SES-2000) and combined fluid mud sampling. leading to highly dynamic mud deposits and large bed-forms such as sub-aqueous dunes is a characteristic feature of tidal estuaries. Often their presence poses navigation risks due to considerable reduction in nautical depth. To secure navigability, especially for the increasing draught of... (read more)
2008-01-01 01:00:00

Hydrography in Monaco

160 Years of Partnership With France
France has been providing hydrographic services on behalf of Monaco for 160 years. This article describes this partnership from the early days of systematic surveying to the present state of affairs (including digital chart production).The long-lasting partnership was formalised in a bilateral arrangement in 2005. The event was called exemplary in the annual report of the International Hydrographic Organization (IHO) for 2005: on 19th September 2005, France and Monaco signed the first known bilateral arrangement formalising the provision of hydrographic services by one country on behalf of the other, in accordance with the revised Safety of Life at Sea (SOLAS)... (read more)
2007-04-04 12:00:00

Hydrographic Surveys at the Port of Sines

The Hydrographic Institute of Portugal (HIP) has been executing hydrographic surveys at the port of Sines since 1973 as part of successive contracts signed with the Port of Sines Authority. Surveying at Sines as been made mainly for port engineering planning, construction and monitoring purposes. "Sines was chosen as the site for the construction of a national deep-water harbour in the early 1970s in response to the increasing trend worldwide towards very large vessels. The Port of Sines began operating in 1978 and its location is 58 nautical miles south of Lisbon. It is one of the few deep-water ports... (read more)
2008-01-01 01:00:00

The Making of an Earth Measurer

Carl Aslakson and the Velocity of Light
In the April 2009 issue of Hydrointernational, Carl Aslakson was mentioned as having devised a method of determining the velocity of light by using Shoran (short-range navigation). This article traces Aslakson’s professional career from his beginnings as “a farm boy in South Dakota, working in the fields with barley beards inside my clothing and dust and perspiration covering my face and hands” to becoming one of the most accomplished surveyors of his era. The name Carl Aslakson is not recognised by the general public and is little known by the community of surveyors. His accomplishments and work influence the surveyors... (read more)
2009-09-02 12:00:00

Converting NL Chart Datum

Consequences of Change from MLLWS to LAT
Following international agreements, the Hydrographic Service of the Royal Netherlands Navy is in the process of changing the Chart Datum in its nautical charts and other products from Mean Lower Low Water Springs (MLLWS) to Lowest Astronomical Tide (LAT). LAT is in general a level 2 to 3 decimetres below the level of MLLWS, so that depths in nautical charts will decrease and tidal height predictions increase commensurately. Transition is expected to take several years. The Hydrographic Service of the Royal Netherlands Navy (NLHS) conducts hydrographic surveys and publishes nautical charts and other nautical information concerning the Dutch part of... (read more)
2007-04-04 12:00:00

Self-installing Wind Turbines

A Different Approach
The Dutch company SPT developed a new foundation concept for offshore wind turbines in order to reduce the costs and environmental impact: a Self Installing Wind Turbine. The concept is based on a tripod with suction piles. As these foundations do not penetrate as deep as single pile structures, a different approach for survey and soil investigation techniques can be applied. Prior to the design of a wind farm, information on the seabed properties, its behaviour and the underlying geology are required. Insight into the morphology of the seabed by multi-beam (Figure 1), and side-scan sonar surveys (Figure 2) can... (read more)
2012-10-05 04:41:29

Solving the Uncertainty Management Puzzle

Understanding the Limitations of Instrumentation
As shipping companies continue to make their operations more cost efficient and environmentally friendly, the demand for high density data has increased. Uncertainty management is a cornerstone to sound Geomatics practice and it’s the uncertainty values that will drive the next generation high density bathymetry surveys. The main goal of uncertainty management is to allow a survey organisation to accurately determine their adherence to international survey specifications (e.g. IHO S44 5th Edition) and/or to internal specifications. Having realistic estimates for uncertainty, hydrographic surveyors can use this information to adequately design, plan and execute survey methodology and special procedures to ensure... (read more)
2011-07-18 02:30:43

Sea Level Rise Modelling

In a Caribbean Small Island Developing State
In 2009, a research project was implemented to study the potential socio-economic impacts of climate change upon coastal communities in Canada and the Caribbean. Grande Riviere in Trinidad and Tobago, one of the study sites, is an important nesting site for leatherback turtles. Turtle watching, part of eco-tourism conducted in that part of the country, is an important source of income for the community. Any significant rise in mean sea level may negatively impact the turtles’ nesting sites and consequently negatively impact Grande Riviere’s socio-economic wellbeing. Hydrographic and topographic surveying techniques and GIS were used to construct spatial models that... (read more)
2011-12-19 04:03:39
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