Navstar as it was then known, was still in its infancy with just seven satellites in orbit and the promise of a full constellation of eighteen or more by 1991. Meanwhile, in the world's conference halls, there was much debate about the electronic chart and its means of presentation, the electronic chart display information system (ECDIS).

Instrument-wise, a basic mainstay of hydrography, the single beam echo sounder was about to be challenged by the practical emergence of multibeam variants capable of providing near complete coverage of seafloors, albeit at much greater cost.

As ever, progress since those days has largely been dictated by the doubling of available computer processing power every 18 months or so. Advances in processor capacities and speeds have accordingly led to comparable advances in survey techniques such as those for mapping, motion sensing and delineation as well as positioning above and below sea. GPS and its Differential variant, along with other means of satellite positioning, is now the norm while also remaining a crucial element for that other major hydrographic advance of recent times, the electronic nautical chart or ENC.

ENCs in effect herald the eventual demise of something which has been going for well over 250 years, the hallowed paper chart. But not just yet. The IMO's Sub-Committee on Safety of Navigation, the mandatory authority for such matters, has still to agree on carriage requirements for the Electronic Chart Display Information System, despite being recently asked to do so by, among others, the classification organisation, Det Norske Veritas. DNV reasons that electronic chart coverage of coastal areas is already good enough to warrant an ECDIS as a statutory item aboard most seagoing vessels, and so reduce groundings by a third.

But is it? Not yet, say some authorities in the US and UK with concerns about the legitimacy of too much basic survey information. According to William Gray, a member of the US Hydrographic Services Review Panel's Advisory Committee, it is often no better than very old lead line-generated data on many current paper charts. Gray attributes this to the poor quality of old National Oceanic & Atmospheric Administration data caused by a general lack of funding and also by the fact that the US Army Corps of Engineers doesn't survey its dredged channels with modern full bottom coverage.

Gray's sentiments are echoed on the other side of the Atlantic here in the UK, where a comparable lack of funding at national level has led to cruise ships and other large vessels using sea areas not surveyed for depth since as long ago as the 1840s, according to the Marine Accident Investigation Branch. It adds that even data used on present electronic charts is sometimes of poor quality.

The MAIB's reservations about adequate resources and funding over many years are underlined by the Maritime & Coastguard Agency, which confirms that financing of centralised UK hydrography has remained static at just £5.4m a year for the last 25 years. The consequences of this reduction in real terms can be seen on the MCA's own website, which includes a map showing dates of the last surveys for UK and Irish waters. Sizeable areas, including virtually the entire Irish coast as well as parts of the Welsh and Cornish coasts and sectors of the North Sea, are denoted in green as surveyed by lead line only between 1840 and1935.

So as this digital age has given us the technological wherewithal to accomplish any number of survey objectives you care to think of, a commitment to providing the necessary resources is another matter. As the Maritime Journal enters its 21st year, it is a sobering thought that we still know less about what lies beneath two thirds of the world's watery surface than we do about the topography of the Moon, Mars and Venus.

Maritime Journal's Hydrographic Survey correspondent David Goodfellow is a founding member of The Hydrographic Society and has been Associate Editor of The Hydrographic Journal for 30 years.