North Hoyle Windfarm Report
6 MCA Radar trials 6.5 Range discrimination test one 6.5.1 Method With Hoylake lifeboat "Lady of Hilbre" stationary, alongside turbine 1, on its Northerly side, Rhyl lifeboat "Lill Cunningham" maintained a Northerly course towards turbine 1. With the radar initially set on its 6 nautical miles range and using a video recorder, the display was recorded continuously from a distance of 4 nautical miles from turbine 1. Additionally, it was noted whether and at what range, if any, the echo of target vessel "Lady of Hilbre" could be visually resolved from the return from the turbine. As "Lill Cunningham" approached turbine 1 the radar was progressively set to shorter ranges and pulse lengths. It should be noted that the initial four nautical miles range was chosen since it was a fair representation of the range at which search and rescue activities would be fully under way. The track followed is in Figure 6-8. Figure 6-8: MCA range discrimination test 1 schematic 6.5.2 Results of the trial As the "Lill Cunningham" approached the wind farm, the echo of "Lady of Hilbre" could not be seen to separate from that of turbine 1. This is shown in Figure 6-9. With "Lill Cunningham" 1.5 nm from turbine 1 and "Lady of Hilbre", 30 metres west of turbine 1 and 25 metres down range from it, the radar was put on a 3nm range, short pulse setting. It can be seen (see Figure 6-10) that there is no echo separation. The anemometer mast, approximately 170 metres to the west of turbine 26, is not separated in azimuth from it due to beam width effects. Figure 6-9: "Lady of Hilbre" in turbine shadow on 6 nm range Figure 6-10: Still in shadow on 3nm range 6.6 Range discrimination test two 6.6.1 Method Since there was no down-range separation of the echo of "Lady of Hilbre" from that of the turbine on these radar ranges, then the following trial was carried out with "Lill Cunningham" initially stationary 3 nautical miles to the south of turbine 1, its radar set to the 3 nautical mile range and "Lady of Hilbre" very close to turbine 1. "Lady of Hilbre" headed slowly towards turbine 6, the object being to note where its echo clearly separated from that of turbine 1 on "Lill Cunningham"’s radar . This separation was however not observed. Therefore, a series of runs were performed by "Lady of Hilbre" while "Lill Cunningham" slowly proceeded towards turbine 1. The courses followed are illustrated in Figure 6-11. Figure 6-11: MCA range discrimination test 2 schematic 6.6.2 Results of the trial While "Lady of Hilbre" remained in the shadow of turbine 1, no echo was received. However, when she kept on a line 30 metres to the west of that joining turbines 1 and 6, the echoes separated at a down range distance of some 200 metres from turbine 1, when "Lill Cunningham" was 1.4 miles from turbine 1, radar set to 1.5 miles range, short pulse, and with the gain control turned down to reduce side lobe and reflected echoes. The observed range discrimination is shown in Figure 6-12. Figure 6-12: Observed range discrimination
|
