Calibrating a new depth sounder
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Category: Hints & Tips
Forum Name: 461 / 470
Forum Description: 461 / 470 Hints and Tips
URL: https://www.myhanse.com/forum_posts.asp?TID=14626
Printed Date: 26 March 2026 at 23:50
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Topic: Calibrating a new depth sounder
Posted By: Philip Huzzard
Subject: Calibrating a new depth sounder
Date Posted: 17 May 2024 at 16:49
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Hi. I'm trying to work out the difference between the position of my through-the-hull depth sounder and the water level, so I can work out the min safe depth sounder reading. Can anyone help here? ------------- Phil |
Replies:
Posted By: DJgun
Date Posted: 18 May 2024 at 03:05
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If you are replacing another sounder then no calibration should be necessary. You are not normally calibrating sounders anyway, you are simply adjusting "offset" to account for position of the sounder compared to surface of the water. If you want the sounder to show actual water depth then you have a + offset in the settings which for typical 36 foot yacht might be +0.3-0.4m. I assume you know the draft of you vessel from specifications. Set the alarm on the depth instrument to be significantly higher than your vessel draft. Some people set a negative offset so that the depth measurement corresponds to "below keel" depth. I think the majority of sailors don't agree with that approach for a number of reason. Primarily they want to know real depth to compare to charts, tide levels and fir anchoring calculations. ------------- DJ.....Sailor Ordinaire HIN DE-HANJ0331J708 |
Posted By: Philip Huzzard
Date Posted: 18 May 2024 at 09:19
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Thanks so much DJ. We're calculating an offset of .45 to be safe. Agree that depth from waterline is probably the best. ------------- Phil |
Posted By: Ian Coverdale
Date Posted: 25 May 2024 at 08:08
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Best way to calibrate your depth sounder is to use a weighted line over the side to measure actual water depth then adjust calibration until depth display shows the correct depth. This eliminates any errors caused by water density, temperature, sensor positioning etc.
Set mine to show 1m less depth than there is. I know there is a tiny bit more clearance ... but my crew don't! ------------- Ian & Andrea SV Gabrielle (H445) Liveaboards - currently Montenegro. www.facebook.com/sailinggabrielle |
Posted By: Philip Huzzard
Date Posted: 28 August 2024 at 18:37
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Thank you so much, Ian. You're not the Deep Purple Ian Coverdale by any chance? ------------- Phil |
Posted By: Johan Hackman
Date Posted: 28 August 2024 at 21:25
You need to read up on the Deep Purple singers. It is either Ian Gillan or David Coverdale. Or are you Phil Lynnot by any chance?  Johan -------------  http://www.johanhackman.se" rel="nofollow - http://www.johanhackman.se |
Philip Huzzard wrote:Posted By: DJgun
Date Posted: 29 August 2024 at 01:05
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FWIW, I fitted a new thru' hull housing for DST810 when the boat was last out of the water, but only inserted the DST810 last weekend. Went for a sail, and the DST810 worked for less than 2 hours before it failed. I changed the lead to another Tee on the network but all to no avail. I then spent the 1.5 hours removing the cable which was secured neatly behind everything as usual, and took it back to the dealer, who tested it and confirmed it was dead. I had read that this range of airmar sensors had been experiencing a higher number of failures, but hoped I would be "lucky". Alas not. When I get the replacement I will run it with the cable loose for a while as I resent taking so much time to install the cabling properly only to have the sensor fail immediately after. Grrrrrrr. DJ ------------- DJ.....Sailor Ordinaire HIN DE-HANJ0331J708 |
Posted By: Johan Hackman
Date Posted: 29 August 2024 at 07:58
Airmar has issued a bulletin about a faulty batch where voltage spikes can ruin the sensor: https://www.airmar.com/Presentations-and-Bulletins" rel="nofollow - https://www.airmar.com/Presentations-and-Bulletins . I don't suppose your sensor would be one of them? Johan ------------- http://www.johanhackman.se" rel="nofollow - http://www.johanhackman.se |