Depth below Keel or depth of water ?

[ancientsailor]

.
... it is a matter of personal preference-

Can't really argue with that. I prefer depth of water - but then I quite enjoy working out depths to anchor and I find it simpler set that way. I tend to treat draught and desired clearance at LW pretty much as a constant - once I've decided on desired clearance. This varies - depending on the conditions and position.

BUT - I do usually have the depth alarm set to leave what I consider a suitable margin below the keel. This I sometimes change - sailing in light airs over soft banks on a rising tide I might set it to 0.5 m. Approaching an area I know less well, I might have it much higher. Usually it's 0.7m (draught is 1.3 m!)

 

[Deleted member 36384]

...... When approaching a harbour or jetty I can absolutely assure anyone on here that the tide gauge on the wall won't show the depth from your transducer or under your keel.

Love it, the blunt facts.

reeac; ...... reading water under the keel- maybe because we're both maths. types and like to see the origin of any graph as zero i.e. the boat starts or ceases to float at zero reading.

Hope you dont have an overdraft and repayment plan.

 

[Leonidas]

I go for depth below keel. At 2.1m draught I often seem to end up edgeing into harbour and I'd rather know the accurate depth below keel.

If I'm following a contour line or deciding where to anchor I've more time to do the arithmetic, and anyway in both those cases I need the height of tide too.

Depth below keel is what counts. But why in feet? Most modern admiralty charts work on meters.

 

[Elessar]

I err on the side of caution......

......therefore set depth below keel. (well props in my case)

If someone unfamiliar with the boat is helming, and they make the wrong assumption, they have more water than they thought not less.

Relating it to charts is a red herring as far as offset is concerned, as you need to add the tide height anyway, just add the offset as well.

But ultimately it is your boat so do what you like!

 

[Poignard]

.....- but then I quite enjoy working out depths to anchor ..

May I have your mobile phone number please?

 

[BruceDanforth]

I have two depth sounders: a Seafarer and a Nasa. The Nasa displays depth below keel and the Seafarer displays depth below transducer. By comparing the two results I'm able to work out the approximate size of the keel.

 

[AngusMcDoon]

I have two depth sounders: a Seafarer and a Nasa. The Nasa displays depth below keel and the Seafarer displays depth below transducer. By comparing the two results I'm able to work out the approximate size of the keel.

I have mine set to depth below Ed's chin when he's standing on the windward float having a pee when it is flying through the air with a boat angle of heel of 8 degrees and a distance from centreline of 3.2m. I have to do some mental trigonometry to work out whether I'm about to run aground or not. I also have to remember how tall Ed is, and take note of whether he's wearing his high heeled sailing boots.

I like making life hard.

 

[ancientsailor]

May I have your mobile phone number please?

only if you promise to let me do secondary port calcs

 

[Poignard]

only if you promise to let me do secondary port calcs

Oh - go on then

 

[Lakesailor]

the approximate size of the keel.

Seems you have a couple of duff depth sounders. It should give you an exact measurement.

 

[BruceDanforth]

Seems you have a couple of duff depth sounders. It should give you an exact measurement.

I can only set the depth below keel in 10cm offsets.

 

[Lakesailor]

Irony smiley is not working.

 

[BruceDanforth]

Irony smiley is not working.

Neither is the piss taking one.

 

[lw395]

.
Why do people get so exercised over this? Surely it is a matter of personal preference. It is no more difficult to add the draught of the boat when using depth for navigation than it is to subtract it when working out when you are going to ground.

As usual some people on here are taking this rather too seriously. Do what you want. if you 'really can't understand' why people do it a different way to you then you need to loosen up a bit.

If you are sailing someone else's boat then I would consider it very bad form to change the echo sounder offset - if you are unsure then use a leadline to work out what it is then live with it.

- W

I agree, but it would be nice if the display said 'below keel' or 'water depth'.
It can be embarrassing if a guest helm assumes it's depth below keel...

 

[dulcibella]

Depth below keel. That way, if the watchkeeper forgets which way it has been set, we are still safe.

 

[Koeketiene]

Depth of water in meters - easier for tidal calculations too

 

[CharlesSwallow]

I go for depth below keel. At 2.1m draught I often seem to end up edgeing into harbour and I'd rather know the accurate depth below keel.

If I'm following a contour line or deciding where to anchor I've more time to do the arithmetic, and anyway in both those cases I need the height of tide too.

In five boats over 42 years I've never done anything else. However, each to his own but the bloke above who doesn't know, worries me a tad!

Chas.

 

[bbg]

In five boats over 42 years I've never done anything else. However, each to his own but the bloke above who doesn't know, worries me a tad!

Chas.

Oh, believe me, I worry myself, too.

 

[Robin]

Corrected to read depth of water allowing for transducer position, but set to read in feet. I have worked most of my life in metric for small dimensions but find feet much easier to visualise in the range where it is important, longer distances are fine in metres. Our chart plotters were set to read in feet also, so no confusion and paper charts were marked clearly 'depths in metres'. Our anchor chain was marked in metres at 5m intervals and if we took the depth of water at HW in feet and set the same number of metres of chain we had put out 3xdepth + 10% initially without having to think too much about it, if needs be we could adjust and add more scope from there.

 

[reeac]

under the keel?

Love it, the blunt facts.



Hope you dont have an overdraft and repayment plan.

No, we always have a cash float.