How deep can a yacht echo sounder sound.

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Mandarin331

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Just an idle discussion which we couldn't answer, maybe some of the transatlantic voyagers can answer this?

The question is what is the maximum depth which a standard yacht (say raytheon) echo sounder can record and what is the reason for the limitation?
 
Rarely more than 100 or 120 metres. Mostly lack the power for any deeper and will depend on nature of sea bed, sea state and how fast you are going. In my experience.
 
My ancient (1980s) but lovely B&G Hecta loses contact with the bottom at around 180m. In anything shallower than that it is, judging by the charts, quite accurate.
 
All depth sounders will have different maximum depths at which they still work, depending on salinity of the water, thermal layers in the water, angle of heel of the boat and so on. My Raymarine sounder sometimes gives up at 110m and sometimes any figure up to 155m.
 
My old ST60 was normally reliable to 100 metres, and the most I ever saw it read was 144 metres.

On my present yacht I installed a 'cheap' NASA Clipper depth sounder, which has proved only reliable up to 35 metres, though it will occasionally manage more.

This is adequate for most purposes, but for blue-water cruising, specially around atolls, being able to get reliable readings up to 50 metres proved a must. (Though maybe these days with charts accurately aligned to WGS84, it might not be quite so essential as formerly).

Incidentally, both these I tested accurate up to 20 metres.
 
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If the water's fairly homogenous (little by way of distinct thermal layers, sharply-defined salinity differences, etc), the soundable depth will be a rough measure of of water cleanliness. If you can sound 150m, it's pretty clean. (In this sense 'dirt' will include small organisms, so it's to some degree also an indicator of the nutritional value of the water for marine life, which is quite low here in the Med.)

The pilot book to the Guadalquiver river cautions that sounders don't work very well, without any insight as to why. As is the case with many rivers, the water is very silty, which dissipates the sounder's signals to the point where there's no readable return. However, they're reliable enough for sounding depths that matter, despite the functional range often being only the first ten metres or so.

parsifal said:
My NASA Clipper has a maximum of 99 metres.
Click to expand...

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).
 
I remember sailing with an ancient sounder which went 'around the clock' at some modest depth and started reading 0.1 fathom.
It was fine on the east coast, apparently, but invented several new shallows in the Channel.
As well as displays losing the leading digit, sometimes the sounder itself receives the previous pulse instead of the current one.
modern units should be cleverer that that...
 
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.

No yacht depth sounder will reach the bottom in even the outer part of the continental shelf, far less the deep oceans. The power requirement would be too high, as it goes up as the square of the depth. Assuming all else was unchanged, the ST60 would need 4 times the power to reach 240m, and 16 times the power to reach 500m, which would cover most of the continental shelves. 1000m would require 64 times the power, 2000m 256 times and so on. You could improve on those figures by having a transmitting array that gave a narrower beam, but it would be prohibitively big for most of our boats.
 
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