North Hoyle Windfarm Report

4 MCA VHF communications trial

4.1 Overview

To evaluate the operational use of typical small vessel VHF transceivers when operated close to wind farm structures.

4.1.1 Equipment used

The following was required for the trial:

• A person with a hand-held VHF radio landed on a turbine platform and a vessel fitted with a typical small craft VHF radio;
• Co-operation of RNLI lifeboats, with RNLI shore stations, HM Coastguard and Mersey Docks and Harbour Board.

4.1.2 Method

In calm weather conditions, a person was landed on the platform of turbine 28 from the Hoylake lifeboat "Lady of Hilbre" which then moved away from the turbine. The Rhyl lifeboat "Lill Cunningham" was stationed as close to the south of turbine 3 as was safe and practical. The person on the platform positioned himself on the northerly side of the turbine tower, i.e. at the point at which the full diameter of the tower lay between him and the direction of the lifeboat.

Using VHF channel 10 and others designated for this purpose by HM Coastguard, the person on the platform transmitted in a normal conversation voice. The quality of the reception was noted by the lifeboat crew and the designated shore stations.

The lifeboat’s VHF radio direction finding equipment then used this signal to determine its bearing and a comparison made with the true known bearing, any difference being recorded.

The Rhyl lifeboat then proceeded in an easterly direction on a course passing as close as was safe and practical to the other turbines on the southern boundary of the wind farm. The quality of the reception being recorded. When past turbine 1, the course was reversed, and the effects similarly noted until turbine 5 was reached. This schematic is illustrated in Figure 4-1.

The vessel’s GPS positions were recorded during the whole exercise so that if any degradation of communication or direction finding is found to exist, the arcs over which this occurred could be calculated.

A principle of these tests was that, if small vessel ship-to-ship and ship-to-shore communications were not affected significantly by the presence of wind turbines, then it is reasonable to assume that larger vessels, with higher powered and more efficient systems would also be unaffected.

During this time a number of mobile telephone calls were made from ashore, within the wind farm, and on its seawards side. No effects were recorded using any system provider.

Figure 4-1: MCA VHF communications evaluation schematic

4.2 Results

4.2.1 VHF Communications

The wind farm structures had no noticeable effect on voice communications within the wind farm or ashore.

However, the use of the lifeboat’s automatic digital direction finding equipment was severely impaired when very close to a turbine tower on the far side of which lay the transmitting vessel’s direction. This was resolved when the lifeboat moved further than 50 metres from the tower.

If this effect is recognised, it should not be a problem in practical search and rescue (SAR).

4.2.2 Other communication methods

• Mobile telephone communications : There was no noticeable effect on mobile telephone communications systems.
• Digital Selective Calling (DSC) : The DSC system communications within the wind farm, contact being made via Holyhead and Liverpool Maritime Rescue Sub-Centres.
• Automatic Identification System (AIS) : AIS operated satisfactorily between vessels and as monitored byHMCoastguard MRSC Liverpool, indicated that both VHF and GPS components operated satisfactorily.
  Since it had already been determined that GPS and VHF were not significantly affected by the wind farm structures, the "Norbay" was simply asked to use her AIS when around and in the wind farm, and Liverpool MRSCC to log the reception from the ship. "Norbay" reported that she picked up other vessels’ AIS transmissions without problems and Liverpool that they had similarly picked up the ship itself.
  It could be argued that there might have been a ship in the area which did not receive "Norbay"s signals, or was not picked up herself by "Norbay". In view of the other evidence, however, this seems very unlikely. As noted in the Executive Summary with respect to on-going data collection, AIS-fitted vessels and HM Coastguard will report any possible omissions.
• Telemetry Links : The UHF telemetry link between the service vessel "Clwyd", its RIB and the BHP Billiton shore station at Gwaenysgor was reportedly interrupted when the RIB was close to turbine towers. Telemetry is normally used on fixed installations for communicating measurements such as wave and tidal heights, wind speeds, etc. However, the Radio Agency has specific requirements for short range devices that do not require licensing and may be used on marine mobiles. Any reported effects should be investigated further.