DartNet

The Valeport factory at Totnes has a tidal range of up to 5m during spring tides. Situated close to the tidal limit of the Dart, it is strongly influenced by flood events driven by heavy rainfall on nearby Dartmoor. Sometimes these events can get a little too close to the factory doors.

A vented pressure sensor is installed below the level of Lowest Astronomical Tide to ensure data is collected even during the low river flows of summer. The sensor datum is referenced to a bench mark surveyed by the University of Plymouth to give an accuracy of ±10mm.

The pressure sensor is connected to a TideMaster installed in the calibration laboratory. The TideMaster controls the sampling pattern, logs the data and is connected to the office network to transmit data via Port-Log to the internet. Data is uploaded every half hour.

Mounted on the roof of the factory, and also connected to this TideMaster, is a Gill MetPak II giving wind speed, direction, air temperature, pressure and humidity.

Duncannon

Installed in association with Stoke Gabriel Yacht Club (http://www.sgba.org.uk/), the gauge at Duncannon Cottage is a vented pressure sensor placed in the central channel of the river to capture the full tidal cycle. The transducer is attached to a sinker weight with 70 metres of cable running across mudflats that dry out every tide protected by hose and weighted with chain.

On the shore is a TideMaster installed at Duncannon Cottage taking care of sampling and logging the data. A Valeport GPRS telemetry modem uploads the data every half hour to the Port-Log server for archiving and display on the internet. The buffering capability of the GPRS telemetry unit compensates for the unreliable Vodafone mobile signal in the area.

The transducer was referenced by a pole to gauge calibration against a calibrated tide board installed by the yacht club at the approaches to Stoke Gabriel.

Dartmouth:

The tide gauge is installed at the Dart Harbour Authority (http://www.dartharbour.org/) maintenance yard in Kingswear with radio telemetry link to the Harbour Masters office on the Dartmouth side of the river. The gauge is a model 740 tide gauge which is the predecessor to the TideMaster.

Valeport have also installed a display at the Royal Dart Yacht Club (http://www.royaldart.co.uk/)in Kingswear that picks up the tide gauge radio transmission, displays the data in real time in the members bar and relays the data to every half hour to Port-Log via the internet.