There is something fine and spirited about a cruising dinghy clearing port on a coastal passage. She is well found and purposeful. Her rig is snug and business-like, and her gear is securely lashed down in its proper place. As the first long swell lifts under her bow, the crew exchange proud smiles. Surely there is no better place to be in the whole of creation, than aboard your own boat at the start of a sea passage?

A light east wind filled Baggywrinkle's red sails as we emerged from Harwich Harbour, bound south down the coast for the Walton Backwaters. Normally when Baggy visits these parts it blows a 'hoolie', and the waves are being battered into rough spume by the contrary tide. But the sea was calm as she cleared Landguard Point and we set a course southward towards the Pye End buoy, marking the entrance to the secret inlet of Hamford Water.

The routine business of passage making began. Although that day's voyage was only a short coastal hop, we took a couple of rough bearings to fix our position on the chart and noted down our location with the chinagraph pencil. Baggy rolled gently in the beam sea and the sun cast oscillating shadows across her varnished hull as she glided gracefully onwards. To the south and east the low grey swells stretched out to a long horizon, indistinct in the summer haze, and interrupted only by a few distant sails and the huge form of a container ship, inward bound to Felixstowe.

One moment we were remarking that the container ship was not as clear as it had been, and then silently, implacably, the mist descended upon us. We just had time to take another bearing of the point before everything was blotted out. Visibility rapidly reduced to just a few boat lengths in any direction. Baggy swept on through a white, impassive world. Only the compass, steady in its bowl, and the sure wind on the beam, remained to orientate us.

The silence was broken by a long mournful cry from the container ship, feeling her way up the channel on radar. She sounded again, seemingly right above us. We imagined the water piling up before her huge steel bows, and our proud vessel suddenly felt very frail and vulnerable. Baggywrinkle carries no radar reflector, and she would not even be an indistinct smudge on the radar screen of the approaching container ship. Our only security was the shallow waters where such ships cannot go. Fortunately to the south of Harwich there is a wide area of dubious shoal water, which today would be our haven. I plotted a new course close in along the shore, reset the grid compass and brought her round to the new bearing. We listened like bats. Slowly the container ship's foghorn grew fainter and the long deep water swells became shorter and steeper as we crept into the sanctuary of the shoals.

I have never been terribly convinced by the match-stick-thrown-over-the-side-and-count-your-pulse school of dinghy speed assessment. Better by far to rig up a proper log. But as we didn't have the proper log, and trying to guess our speed, (or as we call it in the business: "estimating from experience"), could just as easily pile us up on the beach or send us half way to Walton on the Naze, we needed some way to assess when we had reached the mouth of the Backwaters. In a moment of inspiration we lowered the centre plate. Usually Baggy only puts her plate down when she is close hauled. On all other points of sailing it is hauled right up to reduce drag - for speed, SPEED is what we crave. But today we had other priorities.

An hour passed as we slid south on our compass course. We saw nothing and heard nothing, apart from the gurgle of water against the clinker planking and the ominous horns of ships at sea. Then there was a grumble from the centre plate. The galvanised steel was grating over shingle, unseen, a few feet below us. The only thing that could be doing that to our centre plate was the gravel spit on the southern side of the channel into Hamford Water. Immediately we gybed Baggywrinkle round and set a new course to the southwest through the murk. Soon the grumbling stopped, and we were in deep water again. A red can buoy suddenly loomed out of the mist and then quickly vanished astern - one of the channel markers of the entrance to the Backwaters. We sailed on, seeing no further buoys, but they must have been there, close by in the mist.

Then, as quickly as it had descended, the fog was suddenly ripped aside, and a watery world of intricate creeks and inlets stretched out before us. We had entered the secret waters that lie beyond the shingle spits between Harwich and the Naze. As the North cardinal at the entrance to the Twizzle came abeam we swung round to bear south, and there off Stone Point was a motley, collection of vagrant vessels that could be nothing other than an East Coast DCA rally. We had arrived!

No navigator who has sailed for weeks across the wide oceans, and had their desired landfall appear from the horizon bang on the bowsprit, could have felt more elated than we did after that fog-bound coastal passage in our twelve foot dinghy. To find your way across the deep by simple, trusty, traditional means, and bring your craft safely to her destination: this is the sort of memory that the small boat sailor hugs in the mind through the dark days of winter.

So not long afterwards, when I met a fellow at a boat festival in Douarnenez, who had a boat a bare four feet longer than mine, and showed me proudly one of the first hand held GPS sets, I was sceptical. How could he possibly rely on this frail electric gizmo, rather than trusty old compass and chart work? My prejudice was confirmed when I found that his GPS set had cost more than my boat! But as the years have passed, and greater age has crept up on me, (and GPS sets have grown markedly cheaper), my views have grown less forthright. Indeed I weakened so much that I recently bought a set of my own!

Now I know what you are thinking - because I long thought it myself. It's the thin end of the wedge, that's what you're thinking. Soon he'll have given up doing any chart work at all, then he'll even forget about how to do it, and then his little gizmo will go on the blink and he'll be doomed.

But just consider that for only £100 you can now obtain a pocket-sized object that will tell you where you are anywhere in the world to a theoretic accuracy of just a few metres, (and even after the US military have blurred the signal, to about 100 metres, which is still pretty damn good). And that this device will also tell you the bearing and distance of your destination, your speed, your ETA at current speed, and your cross track error, and all this without the inevitable inaccuracies of chart work in a wet and heaving boat.

In navigation books chartwork always looks so easy. There are always three distinctive shoremarks, nicely far apart, that will create a cocked hat of bearings: a distinctive church tower, a handy lighthouse and a conspicuous white house. But when I want to pinpoint my position the horizon always seems to be completely featureless. At best perhaps there are a few offshore islands, which from my low viewpoint are indistinguishable from the coast behind. Finding something to take even one bearing off, which can be unambiguously identified both in the view and on the chart, can tax my ingenuity to the limit. Often navigation is reduced to sailing right up to a buoy and reading its name!

Just because we sail little boats, with the simplest of equipment, does not mean that we have to be Luddite about new developments in electronic position finding. Sure, I have no doubt that I will always pack my chart and compass just in case the GPS fails or I drop it over the side, but I am beginning to wonder whether a second GPS set will soon be the better backup. Do not believe any yachtsman or woman who tells you that they use charted dead reckoning as their main means of navigation and simply glance at the GPS for confirmation. Every yacht I have ever sailed on that is fitted with electronic navigational equipment - be it DECCA or GPS - the electronics are inevitably the main means of navigation. When you have something on board so blisteringly accurate that it even knows which end of the boat it is in, you cannot help trusting to it more than to a smudged dead reckoning plot on the chart.

Inevitably small boat sailors will simply navigate using the graphical readout on the liquid crystal display of their GPS sets. Paper charts will be superseded by electronic ones, downloaded into the GPS's memory. This over-reliance on electronics will probably lead people into trouble, and we will all grouse and grumble about people neglecting the traditional ways of charts and compasses. But then chart work has its pitfalls too - particularly if conditions are bad - when it is all too easy to apply compass deviation the wrong way round or to get your tidal vectors muddled up.

We are at the beginning of a new age of dinghy cruising. As microprocessors become exponentially smaller and cheaper, our little boats will increasingly have the benefit of the most sophisticated electronic equipment, if we choose to take advantage of it. I have no doubt that most of us will inevitably do so, recognising that modern electronics will calculate our position and our desired course more consistently and accurately than a tired and cold crew member, in the rough and tumble of life in an open boat. But something will be lost in that high-tech world of accurate position fixes. We will look back nostalgically to the days of mystery, when we relied on sniffing the wind, a few bearings and perhaps a sounding to fix our position, as a magical time of innocent simplicity. But will any of us choose to go back to it?