Groupama rescue raises interesting lessons

by Martin Balch on 19 Mar 2008
Some interesting issues were raised in the debrief of the Groupama rescue that may be of interest to Sail-World readers. Martin Balch elaborates:

A number of interesting points came from the de-brief of the successful winching operation to rescue the 10 sailors from the capsized Jules Jules Verne Trophy yacht Groupama 3.

When the alarm was received by RCCNZ in New Zealand, replies to distress relay calls for vessels in the area received minimal response from any vessels close enough to respond within a short time frame. Hence, aircraft were tasked and despatched.

Initially, the inverted trimaran was not located by the first searching aircraft at the given EPIRB position.

Both Dunedin rescue helicopters are fitted with very effective radio direction finding equipment which can tune to a wide range of frequencies. This radio direction finding (RDF) equipment has been proven many times, and is well capable of placing the chopper right overhead a floating EPIRB and victims that would otherwise be invisible to searching aircraft.

With Groupama, the 121.5 beacon signal was very weak and intermittent and was not effective for direction finding.

The yacht was quickly located however, as the crew were well prepared and had hand held VHF radios and handheld GPS with which they could communicate with the searching aircraft and were able to supply an updated accurate position. This enabled the boat to be quickly located by the first helicopter giving adequate time to winch all 10 crew members and make their way safely back to shore without running into fuel range difficulties with this long range rescue, 85 miles off shore.

I believe the reason the beacon was not effective for RDF work was it was lashed against the carbon fibre hull instead of clear and high – carbon fibre reacts to radio waves like steel – it shields it. As the digital 406 signal for the satellite went upwards clear of the hull to the satellite, it was successful but the horizontal 121.5 beacon signal that the searching aircraft needed was effectively shielded by the carbon fibre of the hull.

As the 406 signal is digital and transmits in short pulses, it is of no use for DF work, whereas the 121.5 beacon signal is analogue and can be used for DF work.

The 121.5 beacon signal is also weaker than in older 243 EPIRB’s, typically about ¼ of the power of older beacons, hence, it remains necessary to make sure an EPIRB in use is lashed or fixed as high as possible and as far away as possible from metal work and carbon fibre to ensure the 121.5 signal is effectively transmitted horizontally to searching aircraft.

Footnote - one rescue helicopter and a support fixed wing plane from Christchurch and two rescue helicopters from Dunedin were tasked. When the alarm sounded, neither Dunedin helicopter was at base, one was on duty in Queenstown and one was loading in Invercargill. Both returned immediately to Dunedin and were quickly configured for the task ahead – the first took just 6 minutes from landing configured for a medi-vac, to being refuelled and reconfigured for the long range winch job ahead. In less than 3 hours from the capsize, all the rescued sailors were safely ashore.