Thermocline?

[Silkie]

My depthometer is a somewhat cranky Nasa Target and delights in showing random depths which are usually easily ignored but gave an absolutely convincing display of an uncharted (read impossible) shoal while going up the Sound of Mull recently.

Passing Ardtornish without a care in the world I glanced at the depth to see it reading 12m when I knew there was at least 50m under the keel. Apparent depth continued to fall gradually and at 10m I switched it off thinking that it was just a bit confused. When I switched back on we were showing 8m then 7m. I looked anxiously at the chart but no new shoals were charted and I was unaware of any recent volcanic activity. In a smooth progression the numbers dropped - was it a surfacing submarine - or whale? The reading went down to 1.4m and then read 70m which was more like the thing.

Why I allow myself to get so stressed by such events is perhaps better saved for another thread but what do you think was really happening?

It was about 15 mins before the end of the flood on the day after neaps and the rise of tide was only 1.1m. The sun had shone all day, the sea was smooth and the breeze very gentle - we were motoring. I saw no sign of periscope or fluke.

[Arghiro]

Were you in a submarine?

[Silkie]

No. Why do you ask?

[Aja]

It happens all over the place with ST60s too. My stomach still tightens when it happens right enough..

.. heat layers? Could be.

Donald

[Telo]

Hadn't thought of heat layers, but suppose that's possible. I'd guess whales or dolphins might also have the same effect. We were woken up by depth alarm showing about 3m one night. After it eventually went quiet we heard a mammal's breathing tube being cleared nearby.

[Silkie]

The readings seemed too consistent for anything animal, with the possible exception of a large whale. The episode lasted for about 5 mins between 12.9m and 1.4m (offset for below the keel) and I never saw the numbers flicker upwards once until the sounder suddenly started reading the bottom again.

[claymore]

It was a Minkie. A playful little minkie, bored with just minkie-ing around and thought he'd have some fun. They do it a lot.

[aquaplane]

I thought Minkies swung about in the trees?

[Nick]

My depthometer is a somewhat cranky Nasa Target and delights in showing random depths which are usually easily ignored but gave an absolutely convincing display of an uncharted (read impossible) shoal while going up the Sound of Mull recently.

Why I allow myself to get so stressed by such events is perhaps better saved for another thread but what do you think was really happening?

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).

[Arghiro]

No. Why do you ask?

Just a reference to our grey funnel colleagues who were playing in the Sound of Sleat last week.

[Silkie]

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.

[sahona]

Agree with Aja-Don, ST60s a bit erratic, but I thought it was fish.
I did find a worn-through bit on the Xducer cable while fitting new bits and moving old ones - the black wire was severed completely, so maybe next season will be less bum-clenching now it's repaired.

[Fingal]

It was a Minkie. A playful little minkie, bored with just minkie-ing around and thought he'd have some fun. They do it a lot.

But surely you need a leecaunce for a Minkie?

[Telo]

But surely you need a leecaunce for a Minkie?

Umm, you've got me there. I know I'll regret asking this, but, OK, what is a leecaunce? No relation, I hope, to a piecost.

[claymore]

I think it is a piece of Chaucerian legislation to do with keeping cockrells.
Chaunticlere, as I remember, appeared in the prologue...