In article ,
wrote:

I wonder what would the best way to calibrate a depth sounder.
From what I read most depth sounders default setting are calibrated from
the transducer to the sea bed.
Other prefer to adjust the setting to the water line to the bottom of the
sea or from the bottom of the keel.
I wonder what is the preferred method of calibrating?

My depth sounder is one foot bellow the water line. This gives me a good
reference to the water levels printed on the chart plus the proverbial
pilot foot.

Have fun

* wrote, On 6/26/2007 5:32 PM:
I wonder what would the best way to calibrate a depth sounder.
From what I read most depth sounders default setting are calibrated from
the transducer to the sea bed.
Other prefer to adjust the setting to the water line to the bottom of the
sea or from the bottom of the keel.
I wonder what is the preferred method of calibrating?


Do people still use regular sounders? Aren't fishfinders so much
better that everyone has gone to them?

On Jun 26, 7:39 pm, Lew Hodgett wrote:
wrote:

I agreed with the fact that what counts is how much water is under
the keel
However, I have been, for years, using the depth to validate my
position on
the chart.
Conversely, with today's electronics I could say 100 feet + 6
(draft) should
read 106 feet on the chart.
This way I could validate my position with the radar and GPS.

Trying to use chart data, some of it at least 100 years old, to
validate depth, to validate position?

You have got to be kidding.

If you find yourself in less than 20 ft of water, time for a lead
line, IMHO.

At that point, screw the instruments.

Lew

I agree with Lew, their's also tides and water level varriation due to
wind to contend with, not to mention if they have dredged since your
chart was updated. Using depth to tell where you are is really only
useful if your running out of water. If your chartplotter says their
should be 10 feet of water, and your depth sounder says their's only
2, you've got a problem. If you'r coming in from way offshore, depth
can tell you when you'r getting close to the beach, but that's it,
nothing more.

John

In article ,
stormtactic wrote:

In article et,
Lew Hodgett wrote:

wrote:


I agreed with the fact that what counts is how much water is under
the keel
However, I have been, for years, using the depth to validate my
position on
the chart.
Conversely, with today's electronics I could say 100 feet + 6
(draft) should
read 106 feet on the chart.
This way I could validate my position with the radar and GPS.

Trying to use chart data, some of it at least 100 years old, to
validate depth, to validate position?

You have got to be kidding.


If you find yourself in less than 20 ft of water, time for a lead
line, IMHO.

At that point, screw the instruments.

Lew

I sail in a very shallow lake where walking on water is not a miracle.

Some people buy fish finders so they can see the rocks.

Have fun

Up here, in alaska, we walk on water every winter! You just have to
wait for it to get "Stiff"......

Bruce in alaska I have pictures.......
--
add a 2 before @

... Using depth to tell where you are is really only
useful if your running out of water....

Given a working GPS and a WGS correctable chart that may be true.
Those of us who need to work our pilotage in places without GPS
correctable charts still find echo sounders useful tools for
navigation at times. These days this is kind of a specialized use
and as long as you know how the sounder was calibrated it is easy to
do any needed instrument corrections in your head. In the "old days"
when LORAN and RADAR were rare on small boats we used echo sounders
for navigation all the time even in pretty deep water.

-- Tom.

Over here we tend to use the depth sounder more for navigational purposes
and adjusting the scope when anchoring.
I do not think that a depth sounder is ideal for grounding avoidance. By
the time your shallow alarm is sounding you may be already aground. Local
knowledge and experience is probably the best for grounding avoidance.
Over here we have sea bed sedimentation movement. One day you may get
thought the gut and after a wind storm or freshet you may hit the bottom.
My new sailboat draws 6'-2". Today Bruce went thought the gut with his 4
foot draft boat and fed back his depth reading of 6'-6" at low tide via VHF.
Then I proceeded through the narrow passage and made it.


wrote in message
ps.com...
... Using depth to tell where you are is really only
useful if your running out of water....

Given a working GPS and a WGS correctable chart that may be true.
Those of us who need to work our pilotage in places without GPS
correctable charts still find echo sounders useful tools for
navigation at times. These days this is kind of a specialized use
and as long as you know how the sounder was calibrated it is easy to
do any needed instrument corrections in your head. In the "old days"
when LORAN and RADAR were rare on small boats we used echo sounders
for navigation all the time even in pretty deep water.

-- Tom.

wrote in news:4681862b$0$4327
:

I wonder what is the preferred method of calibrating?


Run it aground. Set ZERO. Calibration complete!

Larry
--
http://www.spp.gov/
The end of the USA and its Constitution....RIP

the_bmac wrote in :

I learned to waterski and jump freighter wakes in the Detroit River.
First time I fell I was shocked to be able to stand in neck deep water
1000' from shore...you see in 1968, you couldn't see the bottom in 5'
of water in the Detroit River!!!



My father actually DROVE US through Sarnia, Ontario Chemical Sewage City on
our way to Michigan. I'm amazed when you let go of the rope the skis
actually sunk in the Detroit River in the 60's!

Larry
--
http://www.spp.gov/
The end of the USA and its Constitution....RIP

On 2007-06-28 00:51:08 -0400, Larry said:

wrote in news:4681862b$0$4327
:

I wonder what is the preferred method of calibrating?


Run it aground. Set ZERO. Calibration complete!

Larry

That post should have had a beverage alert! I'm cleaning coffee off my
computer screen now!

Ruby
--
Ruby Vee

Focusing on the negative only gives it more power -- Chinese fortune cookie

"Ruby Vee" wrote in message
news:2007062916192337709-rubyvee3@comcastnet...
On 2007-06-28 00:51:08 -0400, Larry said:

wrote in news:4681862b$0$4327
:

I wonder what is the preferred method of calibrating?


Run it aground. Set ZERO. Calibration complete!

Larry

That post should have had a beverage alert! I'm cleaning coffee off my
computer screen now!

Ruby
--
Ruby Vee

Focusing on the negative only gives it more power -- Chinese fortune
cookie


You got that right.
Good thing with a wing keel.