Depth below Keel or depth of water ?

[mcframe]

Depth of water in metres.

If it reads 1.1 I'm floating. If it reads 0.9 - 1.0 I'm ploughing a furrow in the mud on the bottom of the Exe, or I've just found that damned bank of gravel again. If I'm somewhere else, I never let it read that low.

Depth below transducer for me

I think that's about 20cm below the waterline, so with 1m draught (96cm or 3"1'), that give me just the margin I need and makes tidal calcs simpler

On a different boat, with deeper draught (or fewer keels), I might prefer something else (with a label beside the sounder to help crew).

 

[bonny]

Depth below transducer - but only because I'm lazy and have never updated it. I know (from experience) that we bump when it shows 1.6m (actual draught is specified as 1.9m but I've measured this as 2.1m when re-antifouling and the boat rides high). I siuppose the best bet is to set it to depth of water - this would probably cause less aggro from SWIMBO because she starts to protest when it shows less than 3m. The problem is I would have to re-calibrate my brain!

 

[BrendanS]

Depth below keel is what counts.

What happens if you have a swing keel?

 

[bluedragon]

Maybe somebody already said this, but WHATEVER WORKS BEST FOR YOU! I use actual depth (waterline offset) because that's the way my mind works best when faced with a sudden mental calculation involving depth. But...if under the keel is less prone to error / or intuitively better for you...then stick to it. Same goes for feet/metres. Feet confuses the hell out of me now I've got so used to thinking metric for depth, but a good friend of mine has the same problem when the depth reads metres!! So no right or wrong answer here IMO.

 

[Mandarin331]

What happens if you have a swing keel?

Then follow the same process as the Thames Barges, when the keel rises tack