Emsmet is a comprehensive weather information system recording weather conditions in the Emsworth Channel, both in real-time and historically.

It is particularly useful since its information is derived from instrumentation that is installed on the Emsworth Cardinal (54 deg 49.725’N, 0 deg 56.778’W) which is located at the junction of the Emsworth Channel and Sweare Deep.

The sensors, the associated datalogger, SIM mobile data modem and the software applications used to analyse the data, were supplied by Campbell Scientific Limited.

Installation was carried out by the team led by Adrian Karn from the Chichester Harbour Conservancy

Emworx Limited on Hayling Island, have given advice on system design, built the web site and supplied hosting facilities.

The Solentmet Support Group is responsible for the design and development of the overall system, its project management, and the development of the software used for data control and presentation.

The web site is updated every 5 minutes from the data collection site at the RNLI Station, Hayling Island.

The link to tidal predictions (in the Latest Report page) is from the United Kingdom Hydrographic Office Position coordinates (latitude and longitude) are referred to WGS84 chart datum.

Tidal heights are reduced to Chart Datum, which is approximately the level of Least Astronomical Tide.

The following table shows briefly how the reported data is derived.

*Note 1 - Wave height is calculated by subtracting the minimum water depth from the maximum water depth. An average is then taken over 15 minutes.

*Note 2 - Maximum wave height is calculated by subtracting the minimum water depth from the maximum water depth. The maximum is then recorded.

*Note 3 - Wave period is calculated by taking a Fast Fourier Transform on 512 consecutive samples of the water depth. A spatial maximum is then performed on the resulting histogram. This gives the bin with the greatest frequency. The frequency is calculated from the bin number. Wave periodicity is the reciprocal of this.