Depth Sounder Poll

[markleuty]

Following on from a thread in PBO where the OP wants to put an offset into the reading of his depth sounder, I know this has probably been done to death before but I'm interested in how people set their depth sounders..

 

[sailor211]

Depth of water, ie offset to make waterline datum. Matches my calcs and I know the depth of keel

 

[LadyInBed]

Depth of water, ie offset to make waterline datum. Matches my calcs and I know the depth of keel

Is that when the boat is mob handed or single handed, fresh, brackish or saline water?

 

[westhinder]

Depth of water is academic, if I want to know that, I will calculate it.
Depth under keel is what I have to actually sail, I want to see that at a glance, without calculating.

 

[nigelmercier]

Depth of water, ie offset to make waterline datum...

+1
Anything else is for Sunsail sailors.

 

[James_Calvert]

My sounder forgets any offsets etc as soon as I turn it off. This is because it needs an internal battery for its memory and I'm too mean to give it one.

So I don't bother with offsets or alarms. I know I go aground at an indicated 1.1m or thereabouts. That's all I need to know.

 

[lw395]

It does not matter.
What matters is that everyone on the boat knows what the sounder is telling them.

 

[prv]

It does not matter.
What matters is that everyone on the boat knows what the sounder is telling them.

...and if they might not all know, then below-keel is the fail-safe option.

(For our first season in KS, the reading was neither below the keel, nor from the waterline, nor even below the transducer - someone had clearly got confused in setting the offset.)

Pete

 

[Seajet]

I use depth of water to relate to charts; I know how deep my keel is.

 

[BrianH]

I have no choice, it's a cheap fishfinder with no offset possibility. So I am stuck with depth under transducer, which is no problem in practical terms, just do the (simple) sums.
If I could chose, it would be offset to actual depth. In every other way it is excellent; large clear display and always precisely correct.

 

[epervier]

When it shows 0.0 mtrs I'm aground

entering Ashlett creek a few days ago it was a bit tight,

 

[snowleopard]

Reasons for knowing depth under keel: to avoid hitting the bottom.

Reasons for knowing the depth of water: to calculate anchor scope; to get a position line from soundings.

 

[jwilson]

Depth of water under keel. That's what I want to know 99% of the time. If I want depth of water for a nav/anchoring calculation (ie not that often) I can add 6 feet.

Depth sounders do tempt you to cut corners: the first time I ever ran aground accidentally was in the 1970s shortly after I'd fitted a shiny new £29 Seafarer and was watching it's flickering spinning neon. Before I had it I'd have been in deeper water.

 

[Elessar]

to get a position line from soundings.

tee hee.

anyway, seriously, if you're really getting a position line for some bizarre nostalgic reason, you're already having to do a calculation to add the rise of tide. Even if you set the depth sounder to depth of water, it will only relate to the charts for about an hour a year.

however, if set under the keel, it is the safe option for strangers on the boat. It adds a small risk when anchoring, though not as much as one of the boat share companies in the solent that sets it to a meter under the keel! really.

But......

LW395s answer is the best so far.

 

[DJE]

Reasons for knowing depth under keel: to avoid hitting the bottom.

Reasons for knowing the depth of water: to calculate anchor scope; to get a position line from soundings.

But what you really want for anchoring is height from sea bed to anchor roller isn't it?


Mine is set to depth under keel as the original system on the boat couldn't do offsets in the other direction. The new one will do offsets in either direction but it is now too deeply ingrained to change.

 

[Tony Cross]

It does not matter.
What matters is that everyone on the boat knows what the sounder is telling them.

+1

 

[jerrytug]

Under the keel of course,I want to know when I'm going to touch.

 

[xyachtdave]

When it shows 0.0 mtrs I'm aground

entering Ashlett creek a few days ago it was a bit tight,

That amount of water under the keel doesn't even raise an eyebrow around here!

 

[nigelmercier]

Under the keel of course,I want to know when I'm going to touch.

Don't you know the depth of your keel?

 

[markleuty]

It does not matter.
What matters is that everyone on the boat knows what the sounder is telling them.

I would agree with Elessar that this is the best post so far.

Personally I have depth of water and it always freaks me out when I go on other people's boats and the reading is less than I know their draft it.

It should be part of the "safety" briefing.