How deep can a yacht echo sounder sound.

[JumbleDuck]

In the Clyde, my through hull mounted Raymarine ST60 depth sounder regularly lost the bottom between Ardlamont Point and Tarbert. The depth at which it stopped varied a bit, but around 120m.

I'm fine there, but lose the signal between Colonsay and Iona.

Years ago I took a friend sailing on the upper Clyde, As we tacked up Loch Long, he started getting a bit twitchy about how near we were to the shore. "Is it deep enough?" he asked. "Why don't you check the echo sounder?" I said. He switched it on, and said "There's no reading". So I suggested he try the deeper (fathoms) range. Still no reading. Until he noticed that the little red blip at the top was actually two little red blips: we were in sixty fathoms a couple of boat lengths from the shore.

 

[AntarcticPilot]

I'm fine there, but lose the signal between Colonsay and Iona.

Years ago I took a friend sailing on the upper Clyde, As we tacked up Loch Long, he started getting a bit twitchy about how near we were to the shore. "Is it deep enough?" he asked. "Why don't you check the echo sounder?" I said. He switched it on, and said "There's no reading". So I suggested he try the deeper (fathoms) range. Still no reading. Until he noticed that the little red blip at the top was actually two little red blips: we were in sixty fathoms a couple of boat lengths from the shore.

I know; my rule for tacking was usually to tack when the depth sounder read 10m, and that often felt very close to the shore! Bit different down here, where I've had to thread my way through a narrow passage with less than a metre under the keel.

 

[Poignard]

(...)
If it's the same as the one I used to have, it's only the display that has that limit, not the sounder. It will record 102m of water as 2 metres (to the occasional alarm of crew).

Yes, that's true. I suppose the ultimate limiting factor is the pulse rate. If the echo has not returned before the next pulse is transmitted, then a false reading will result. Have I got that right? It's a long time since I had anything to do with electonics other than buying just something and plugging it in!

 

[JohnGC]

Yes, that's true. I suppose the ultimate limiting factor is the pulse rate. If the echo has not returned before the next pulse is transmitted, then a false reading will result. Have I got that right? It's a long time since I had anything to do with electonics other than buying just something and plugging it in!

I think you probably are right. In clear & deep waters my ST60 jumps from around 130m to 3.3m. If we sail into deeper water then the reading shows over-range. If shallower, it returns to a sensible value. Had me dashing down to the chart table the first couple of times it happened.

John

 

[pagoda]

I'm fine there, but lose the signal between Colonsay and Iona.

Years ago I took a friend sailing on the upper Clyde, As we tacked up Loch Long, he started getting a bit twitchy about how near we were to the shore. "Is it deep enough?" he asked. "Why don't you check the echo sounder?" I said. He switched it on, and said "There's no reading". So I suggested he try the deeper (fathoms) range. Still no reading. Until he noticed that the little red blip at the top was actually two little red blips: we were in sixty fathoms a couple of boat lengths from the shore.

Basically off scale for a lot of Loch Ness and there are lots of places in Western Norway where there is >100m of water 10metres off a rock bound coast.
However , I am more interested once it reads <20m, so as long as it's working properly at the low end that is much more relevant.

 

[JumbleDuck]

I know; my rule for tacking was usually to tack when the depth sounder read 10m, and that often felt very close to the shore! Bit different down here, where I've had to thread my way through a narrow passage with less than a metre under the keel.

My crew has just reminded me of sneaking in to the anchorage at Eilean nan Gabhar in Loch Craignish rather optimistically from the west ... I think we had 30cm under the keel, but it may not have been quite as much as that.

 

[pagoda]

My crew has just reminded me of sneaking in to the anchorage at Eilean nan Gabhar in Loch Craignish rather optimistically from the west ... I think we had 30cm under the keel, but it may not have been quite as much as that.

I've been in there.. at least it is mud once you drop the hook, and decent holding at that.

Near Stavanger once we found a jetty with space to tie up. Drifted in rather slowly and found maybe 10-20cm under our keel. Over bare granite. Checking the tide it was low water, phew. Rise of 10cm to come so we went to bed feeling quite safe

 

[HinewaisMan]

Coming across the Indian Ocean we heaved to over what we worked out to be the deepest area we'd cross so that Jean and the crew could go for a swim. About 13,000 feet if I remember rightly.

They said it felt really weird to think there was around two and a half miles of water below them as they swam around, frolicking; to me swimming is weird so I stayed aboard and amused myself trying to work out how long it would take a beer can to sink to the bottom (about 5 hours I think).

Back on topic, I can advise that my Raymarine ST60 sounder cannot see the bottom at 13,000 feet.

 

[JumbleDuck]

I've been in there.. at least it is mud once you drop the hook, and decent holding at that.

It's a very nice anchorage, and would be nicer still without the semi-abandoned fish farm stuff.

 

[ffiill]

Shows how many of you sail in shallow water.
Just off Eilean Donan Castle mine looses it at plus 400 feet! next to the main road-it just says deep as it does in Loch Carron