Where exactly do you calibrate your echo-sounder to?

Interim stats at 1847

snowleopard said:
Probably worth putting this one up as a poll.

FWIW mine is set to depth of water.
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Don't know how to set up a poll with the new software, but of about 20 replies so far (including mine), the interim stats are:

Under keel: 10
Waterline: 6
Other opinions but no data given, or depth set to (stuck on) transducer height: 4

So far then its roughly 2:1 in favour of calibrating under the keel.
 
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Waterline. I know what depth of water I can sail in, I just need to know what depth of water I am actually in at the present time, and, from a navigation point of view, how this relates to the charted depth.
I can, sort of, understand why some people set theirs to 'under keel' - they're boat oriented rather than environment oriented - but why anyone would use such an arbitrary reference as 'under transducer' is mind boggling to me! Why not set it to 'under the dynaplate, or 'a bit less than that ding on the keel we noted last year' or somesuch random point from which you happen to know the depth under your keel.
 
From the waterline; then I know if it reaches 1.5 I am about to touch. Plus it makes it easier to calculate tidal heights, anchoring depths etc.
 
Salty John said:
Waterline. I know what depth of water I can sail in, I just need to know what depth of water I am actually in at the present time, and, from a navigation point of view, how this relates to the charted depth.
I can, sort of, understand why some people set theirs to 'under keel' - they're boat oriented rather than environment oriented - but why anyone would use such an arbitrary reference as 'under transducer' is mind boggling to me! Why not set it to 'under the dynaplate, or 'a bit less than that ding on the keel we noted last year' or somesuch random point from which you happen to know the depth under your keel.
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Some E/S 's cannot be offset to read one or other - my Echopilot says it can - but I found it wasn't reliable once offset, so put it back to factory default zero. It's not my choice to have it at transducer level - just it works best that way.
 
lumphammer said:
From the waterline; then I know if it reaches 1.5 I am about to touch. Plus it makes it easier to calculate tidal heights, anchoring depths etc.
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Same here.

I also have a repeater for my NASA echo-sounder, hence two alarms that can be set to different depths. One is always set to 2 metres.

One alarm bleeping tells me I should do something, two alarms bleeping tells me I'd better do it quickly!
 
Babylon said:
Following on from a previous thread, I'm interested to know whether the majority of people calibrate their echo-sounder to the waterline or to under the keel?
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I stick to a good old fashioned whirly-LED Seafarer (in proper, God-fearing fathoms at that) so I have no choice - it gives me depth under the transducer. However, since the bulb on the keel shows up as a nice clear blip at 3' or so it works very well, and even gives quite a clear picture of the depth available relative to the draught of the boat.
 
'nuther vote for waterline.

(Reason: easier to relate to tide / expected depth - as well as logic & common sense :D)

Andy
 
johnalison said:
I must be the only person in the country who leaves it at depth-under-transducer. There are several reasons for this. First is laziness; I can't be bothered to change it. Secondly, sailing with only 0.5m showing on the dial gives me the willies, though I'm happy to sail in 2m of water. Thirdly, I've been sailing for yonks with sounders that can't be adjusted and am just getting too old to adjust to changes.
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I'm the same. The foot or two difference between transducer and waterline gives you a margin for error and at shallow depths it is academic anyway, the bottom is probably sloping or uneven anyway.
 
orbister said:
I stick to a good old fashioned whirly-LED Seafarer
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wish they did a modern version with a smaller display. So much better than a digital readout. Digital readout just flashes when the mud is churned up as it gets confused, the old whirly thing you just see the dot blurring so you know it's soft and can still see the bottom.

Anyway, keel. (well skeg actually for me as I don't have keel in a yachty sense, but the deepest bit of the boat). A 1m offset so the maths is easy too.

On the digi displays they should let you set up a word to put on the display (ie depth or depth under keel) so guest skippers don't get confused.
 
In an ideal world I would have it calibrated to water depth, but my current boat is from the transducer and I don't know how to change it! I do know that when it reads 1.1 we are aground, tested last week in Hamford Water and it's fairly accurate!
 
Babylon said:
Following on from a previous thread, I'm interested to know whether the majority of people calibrate their echo-sounder to the waterline or to under the keel? And, if under the keel, do you further complicate matters by adding an extra safety margin of say 0.2m to the calibration.

We're currently calibrated to under the keel plus a small margin, as this is how the thing was set when we bought her, and I've got used to reading how much water there is between seabed and fibreglass. I'd like to recalibrate to the waterline so that I've one less calculation to do when working out tidal heights, but I'm worried I'd forget that we've changed and run the ship aground!

Babs
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I got a piece of line with a weight on, dropped it in the oggin and let it touch the nice hard bottom, then I measured the depth of water. I then set the B&G at the depth, thats it, so what I see is what the depth is, makes it easier when calculating, when it reads 1.6 Im going to touch!
Stu
 
Elessar said:
wish they did a modern version with a smaller display. So much better than a digital readout.
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It's like digital vs analogue clocks: you don't actually have to read a whirly echo sounder. If you do then, as you say, any smearing of the return can be very useful - you don't have to trust the electronics to decide where in a complicated return the bit you care about is.
 
I'm for waterline, i.e. total depth of water, but I once got badly caught out by someone thinking it was depth under keel.
Whatever it is it should be labelled imho. Does not matter much which, but I was naive and thought everyone did waterline. Shows how wrong you can be!
 
johnalison said:
I must be the only person in the country who leaves it at depth-under-transducer. There are several reasons for this. First is laziness; I can't be bothered to change it. Secondly, sailing with only 0.5m showing on the dial gives me the willies, though I'm happy to sail in 2m of water. Thirdly, I've been sailing for yonks with sounders that can't be adjusted and am just getting too old to adjust to changes.
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Me too, I leave it at the default setting (under the transducer). Likewise all the alarms are at default (off). My logic for this - apart from sheer laziness - is that my sounder (a Seafarer 901) needs a dry battery in it to retain the settings when the main 12v supply is switched off, which I then don't need to fit/ periodically replace.

Depending on how much we are loaded, I know we touch soon after the sounder shows under 1.3m - and if it's soft mud we get stuck fast at about 0.9. I learnt those figures early in our first season with the boat ...
 
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