Nick wrote:As you know we had four years of this after fitting the new engine. Finally fitted a new gauge and it works most of the time now (same transducer).
As I say, this wasn't the usual random stuff but a completely convincing facsimile of shoaling water.
From our East Atlantic blog:
We finally left Cascais at 11.45 with two reefs in and a brisk Easterly blowing up to 18 knots. A few miles out we met a strange line where the water went instantly from green to blue, with lots of broken water . . . it looked like a reef, and alarmingly the echo sounder suddenly showed 2m. I hastily rechecked the chart . . . it was definitely a tidal effect, but I held my breath as we crossed it.
Has it been wet? I've dived all over the West coast, and regularly seen a halocline whereby freshwater lies over the top of salt water. The fresh water is also usually very peaty and dark, and you can get brilliantly clear sea water under it, although it's usually gloomy.
I'd guess it usually occurs shallower than 12m, perhaps at 5 or 6, but I've not dived very late in the year when runoff could be grester.
It hadn't been wet and was the last day of a spell of fine weather. A fair amount of fresh water flows into Loch Aline and had it been the end of a wet week with the tide ebbing I could easily have imagined layers of differing salinity being the cause.
