Current measuring navigational buoyone buoy, two purposes

Rijkswaterstaat

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Improving information supply to large ships entering the Port of Rotterdam by combining navigational and measurement facilities in a buoy

Peter Verburgh, Rijkswaterstaat Information Supply division (CIV)

Rijkswaterstaat

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Outline of presentation

• Rijkswaterstaat, a brief company overview• Situation• Present data supply• Reasons for renovation• Why a buoy?• What buoy to use?• The deployment• The data• Summary, conclusions and time for discussion.

Rijkswaterstaat

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Rijkswaterstaat

Part of the Dutch Ministry of Infrastructure and the Environment

Responsible for design, construction, management and maintenance of:

• the main road network

• the main waterway network

• the main watersystems

Rijkswaterstaat

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Central Information Services

CIV provides reliable and fit-to-business information for Rijkswaterstaat

Peter is project manager at CIV

Rijkswaterstaat

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Situation

Very busy shipping areaLarge ships need information to enter Rotterdam harbor safely

Rijkswaterstaat

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Present information supply

• Meteo• Waves• Current from 2-D

model• Current from pole• Tide

Rijkswaterstaat

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Present information supply

• Wind• Waves• Current from 2-D

model• Current from pole• Tide

Rijkswaterstaat

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Reasons for renovation

• Better predictions• 3D information instead of 2D• Reduction of maintenance costs• Present measurement pole “Maasmond” out of order

Rijkswaterstaat

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Future information supply

• Meteo• Waves• Tide• Current from 3-D

model• Surface current from

HF-radar• Current from buoys

Rijkswaterstaat

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Why a buoy?

• Relatively low cost solution compared to pole (100k vs 1000k€)• Relatively short time to put into practice (8-10 months vs 2 yrs)• Easy to change the location• Low cost of ownership (maintenance is done on-shore)

Disadvantages:• Vulnerable• Little space for solar panels, therefore very limited power• No fixed location, it moves on its anchor• The ADCP is constantly moving

Rijkswaterstaat

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What buoy to use

• Commercially available measurement buoys• Specifically designed measurement buoy• Lesson learned from previous development in

Zeeland• Operational requirements

Decision: Buoys will be based on ‘Zeeland’-buoy

Rijkswaterstaat

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The production

• An existing contract for navigational buoys was used (no tender)• Order based on functional rather than technical specifications• Supplier is responsible for proper functioning• Rijkswaterstaat is responsible for data-connection (on-line!)• Rijkswaterstaat is responsible for deployment

Rijkswaterstaat

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The production

Two buoys, one spare ‘measurement-core’

Flotation segments from France (Mobilis)

Central cylinder made in the Netherlands (Rombouts)

Electronics designed and made in France (Mobilis)

ADCP and UMTS/GPRS supplied by Rijkswaterstaat CIV

Put together in the Netherlands (Mobilis/Rombouts)

Rijkswaterstaat

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The deployment

From a.l. to b.r:The vessel ‘Rotterdam’, the buoy ‘Maas-Oost’ in the crane of the ‘Rotterdam’, both buoys and spare core on deck of the ‘Rotterdam’, the buoy ‘ODAS-MV’ on location

Rijkswaterstaat

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The data

• First brief impression: looks acceptable…• Comparison with model output: reassuring!• Evaluation versus separate measurement with

shipborne ADCP ongoing

Rijkswaterstaat

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The data

Difficulties encountered:

• One of the beams seems to reflect from the anchoring chain• Occurrence of ‘moving bottom’ may reduce accuracy• Complex data conversion suspect to introduce (timing)errors• Settings are location-dependent and have to be done very carefully

Rijkswaterstaat

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Summary

• A navigational buoy can be succesfully transformed into a online measurement platform, while retaining its navigational purpose.

• Vertical current profiles can be measured from a buoy• Take into account operational difficulties• It is not as ‘cheap’ a solution as some managers would like it to be

Rijkswaterstaat

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Questions / discussion

Thank you for your attention!

…Time for questions and discussion