Thru hull depth transducer on Centaur

Depends how you want to regard the readings ...

If you set it as depth under the transducer - then you will always have to amend the figure for how far below waterline the transducer is.to get real depth of water.

If you offset the reading to account for being below waterline - then you will have real water depth displayed.

You mention 3' .. the approx draft of a Centaur .. but your transducer will be below waterline and not related to the 3' draft ... more like half that ..

My suggestion is to decide what setting you want .. depth under transducer with no correction ... or offset to correct displayed depth related to actual waterline.
Find a nice spot where bottom is reasonably level, hard bottom preferred ... stop - plumb the depth with weight and line .... read off echo-sounder depth at same time ... this will then give you the offset to apply. I suggest you do this in a depth of 5m or more ... to avoid reflected signals and where transducer can play games in real shallow water.

Just a comment : You say location near the heads .... I usually prefer a transducer to be more aft ... under an aft bunk or such about inline with engine as near centre line as possible ... as that area will rarely be out of the water when sailing / pitching in seas etc.
 
Transducer position, I agree with Refueler. Ours is under the companionway step. Not at the front. And the offset gives us real water depth, no ambiguity there I think. You know your own draft, a meter, give or take. Some do like the offset at keel depth, I can do that mental arithmetic, and know that I have charted depth plus rise of tide on our sounder. There is surely no point in that odd practice of adding a bit for safety. It’s a personal thing, the offset though. I see the logic of setting it to the keel, its just not what I prefer.
 
Whatever you decide to use for an offset make sure you stick on a label next to the readout saying depth of water or depth below keel.. This helps me when my memory fails or will help the crew who have not been on your boat before.
 
Personally for a centaur with a 3ft draft and bilge keels I would set depth below keels so if you see 3ft that means you are not aground etc . If you surf into chi bar you will be able to do it as the tide rushes in(with wiind behind you ideally) much before many larger yachts which is quite exciting for a centaur on the rising tide. Personally if it’s simplest to fit by heads then go with that but I guess it depends if you already have a transducer hole? My recollection is transducer made by Airmar for both brands of plotter etc and have a tendency to fail after a few years . Get down to port Solent maybe and speak to marine superstore for thoughts?
 
ashtead said:
Personally for a centaur with a 3ft draft and bilge keels I would set depth below keels so if you see 3ft that means you are not aground etc . If you surf into chi bar you will be able to do it as the tide rushes in(with wiind behind you ideally) much before many larger yachts which is quite exciting for a centaur on the rising tide. Personally if it’s simplest to fit by heads then go with that but I guess it depends if you already have a transducer hole? My recollection is transducer made by Airmar for both brands of plotter etc and have a tendency to fail after a few years . Get down to port Solent maybe and speak to marine superstore for thoughts?
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Personally, I seem to have some sort of 6th sense, and I can tell when I’m aground.🤣
 
Personally for a centaur with a 3ft draft and bilge keels I would set depth below keels so if you see 3ft that means you are not aground etc
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?? Do you mean set the reading at zero offset ? Because then that would make sense. The position he has chosen is approx 2ft below waterline ... so a reading of 3ft indicates about 1ft below keel. Assuming of course he's level and not sailing - leaning over ... that 1ft could easily be lost if transducer as shown is on port side and he's leaning over to stbd ...
 
Refueler said:
?? Do you mean set the reading at zero offset ? Because then that would make sense. The position he has chosen is approx 2ft below waterline ... so a reading of 3ft indicates about 1ft below keel. Assuming of course he's level and not sailing - leaning over ... that 1ft could easily be lost if transducer as shown is on port side and he's leaning over to stbd ...
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This sort of confusion is why ours is set to surface, ie showing true water depth.
 
Chiara’s slave said:
This sort of confusion is why ours is set to surface, ie showing true water depth.
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Its like most things simple gets put aside and all sorts of recc'd gets put forward ...

I'm going to be mounting my spare NASA Dual soon on my MoBo ... guess what ....

I will measure the depth alongside ... set my display to the same .......... QED
 
Thanks for all the replies. A couple of weeks ago I fitted the transducer (Raymarine CPT-S In Hull Transducer) near the heads and set to 3ft. I got nothing on the display at all.
So I reset the transducer back near the engine water intake. Still nothing, no errors just as the screenshot, any ideas what I am doing wrong please?

1747081258957.png
 
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