Stars rather than satellites may be the only trustworthy guides at sea over the next few nights as the dreaded Week Number Roll-Over (WNRO) hits certain navigational systems.
Billed as a "dress rehearsal" for the millennium bug Y2K, the problem is expected to take effect from tomorrow and last for several days.
However, a leading Cork consultant and former naval officer has predicted the roll-over in the Global Positioning System (GPS) will have little impact on most receivers.
That said, Mr Gary Delaney of Charternav GPS in Cork went to Dublin Port yesterday to upgrade the software on a Swedish cargo ship. The insurers for the ship, Azalea , insisted the vessel's GPS system be checked in advance of tomorrow's event.
GPS is a network of 24 satellites developed by the US Air Force to provide navigational information to the military. Since the system's introduction in the 1970s, it has been adapted for civilian use, most commonly as a precise navigational aid at sea and in the air.
It is also used by surveyors, scientists, geographers and engineers on land.
The GPS system calculates time by counting the number of weeks since Jan 6th, 1980, up to a maximum of 1,024 weeks. After this, the calendar resets to zero - similar to a car's odometer that resets after 99,999 miles. The first such roll-over is due to occur at midnight between Saturday and Sunday and will occur again about every 20 years.
As a result, some GPS receivers may not be able to locate the satellites, resulting in a malfunction; or there may be a time delay in locating the satellites. A more serious problem for those relying on GPS only is that the receiver may appear to be working, but may display inaccurate positions, times or dates.
Earlier this month, the Minister for the Marine and Natural Resources, Dr Woods, was criticised for not issuing a warning statement earlier. Dr Woods emphasised that information available from the US government, as owner of the satellites, was that the date changes were unlikely to affect the operation of the satellites or ground control centres.
The Minister urged owners to check with their receiver manufacturer or supplier to confirm the equipment was both EOW rollover and Y2K compliant.
Most experienced vessel owners do not rely on GPS alone - given that most electronic equipment is still categorised as an aid to navigation. Aircraft pilots may only use it as a navigational aid also, and not as a primary system. Receivers manufactured in the past two to three years may not be affected. However, owners of older receivers may have to reboot equipment to ensure it functions accurately, as the GPS system relies on accurate time measurement.
Charternav GPS has opened a 24-hour helpline. Callers are advised to have the name of the manufacturer of their GPS unit available, along with the model, serial number, and the firmware version or release date displayed on the start-up screen. Charternav GPS can be reached at (021) 832990 during business hours today and Sunday, and at (021) 375164 outside office hours.
Websites also giving information on WNRO include http://www.trimble.com, set up by one of the distributors, Trimble.
