Compounding the problem, the review was sponsored by the BoatUS Foundation and the giant US chandlery chain, West Marine. West Marine is offering refunds to customers who bought the McMurdo products.

The ESF tests were run on six 406MHz beacons and while all six obtained a minimal acceptable level of distress alerting by producing a Doppler location, the tests run on the GPS based location through GEO satellites showed McMurdo's Precision 406 MHz GPS EPIRB and its Fastfind Plus 406 MHz Personal Location Beacon both apparently failed to produce a position.

According to Ritter: "The tests revealed that purchasers of these GPS-equipped 406 MHz beacons are apparently not getting what they paid for and are operating under false expectations. This lack of GPS data could result in tragedy that might have otherwise been prevented."

Mullins said as a result of Ritter's report, McMurdo is to commission its own independently witnessed tests to establish how its products perform under the same test conditions.

"If these new tests, which will be completed within the next 30 days, show the products perform as expected, and contradict Doug's report findings, the results will be published, " said Mullins. "If the product fails to meet our high performance standards, we will immediately take whatever action is required."

Chris Hoffman, technical director of McMurdo added: "Our products meet all American approval requirements and fully comply with the FCC and RTCM standards.

Doug's results appear to show our products did not acquire and transmit a GPS location. We are mystified by his results because our EPIRBs and PLBs were tested pre-trial and obtained GPS lock within two to three minutes."

Hoffman went on to say that when independently tested elsewhere in the United States, Europe and Australia, the same products achieved GPS acquisition superior to that reported in his recent trials.

Anxious to reassure customers, Hoffman insisted they could be confident that, whatever their GPS fix status, these McMurdo products will still transmit a distress alert, within three minutes, to the GEO-Stationary satellites for onward transmission to the rescue authorities.

"In the event that this alert does not contain GPS location, " he said, "the position will subsequently be determined by the LEO satellite network."