I have used one of these devices, so am not coming here completely from uninformed prejudice, but while I can see its use for sneaking up a narrow channel in the dark, or poor visibility (as long as you are confident of your waypoints), I am at a loss why anyone should prefer to use a tiny screen instead of a 43 inch by 29 inch chart. Where, pray, is the advantage? However, by far and away the worst thing about a chart plotter, is that as you scale down ie, (for those who get confused about the difference between large scale and small scale), show a larger area of (land and) water on the screen, most chart plotters eradicate 'extraneous' detail. Like buoys. Or reefs. Now the smallest scale chart will most definitely omit buoys and even anything but the most major lighthouses, but it will never omit a reef. So if you are racing across the Indian Ocean, as a Danish boat was recently, and happen to make a blunder that sends you heading directly for a reef a couple of hundred miles north, north east of Mauritius (as far as I could deduce from the radio), then your navigator, placing his fix on the chart, will say, 'Good heavens!', or words to that effect, 'there's a bally reef in the way', and advise the helmsmen to alter course accordingly.
However, if he's sitting looking at his chart plotter, cranked down to small scale, the reef won't be shown and there will be no warning of its existence until the boat blunders on to it.
Here were the excuses:
- "The boat was going very quickly". Well, about three times as fast as the average cruising yacht, running in the Indian Ocean. About the speed at which a decent-sized ship would travel in times long before GPS. Considerably more slowly than a WWII bomber.
- "GPS isn't always that accurate". No? Well, since that nice Mr Clinton turned off the 'wobble factor', it has been sufficiently accurate for courier services to navigate by. I dare say it will show you when you are within cooee of a fair-sized reef. And if it isn't that accurate, why are they relying on it so heavily?
- 'The charts aren't always accurate". Well, true, but the French and the British were squabbling over that bit of water a couple of hundred years ago and had a pretty good idea of where all the bits of rock that might damage their ships were located. And if the charts aren't that accurate, is it not rather poor seamanship to go hurtling along in that manner?
Of course, we can all make this mistake and many others; I am far from the perfect navigator. A kind guardian angel guided me through a cluster of rocks on one occasion when my pilotage was well out. They were well large enough to wreck my boat. I've come out of the hatch to see the beach but a few yards ahead. I've hit a navigation mark before now and run aground more times than I care to remember. But in each and every case, it has been my fault. Sure the charts have sometimes been misleading and the navigation mark wasn't where it was shown, but as I was doing the navigation, the responsibility was mine. GPS and chart plotters add to the information available to the navigator. It should be easier than ever to avoid shipwreck. No-one can blame the chart plotter for assisting the stranding - but it's increasingly common to hear it being used as an excuse.