Which echo sounder is good up to (almost) zero depth?
 

Hi all, I want to upgrade my echo sounder but I find that all of the
units I am looking at give up at around half a meter - unlike my 20
years old unit that I wanted to replace (I need zero depth performance
for inland waterways). Does anybody know of a unit/brand/type that would
work for me? I'm not interested in fish, just displaying depth.

TIA,

S

Which echo sounder is good up to (almost) zero depth?
 

"Salomon Fringe" wrote in message
. ..
Hi all, I want to upgrade my echo sounder but I find that all of the units
I am looking at give up at around half a meter - unlike my 20 years old
unit that I wanted to replace (I need zero depth performance for inland
waterways). Does anybody know of a unit/brand/type that would work for me?
I'm not interested in fish, just displaying depth.

TIA,

S

To heck with a depth sounder, you need one of these.
http://www.mudbuddy.com/News%20&%20P...nformation.htm

Which echo sounder is good up to (almost) zero depth?
 

"Salomon Fringe" wrote in message
. ..
Hi all, I want to upgrade my echo sounder but I find that all of the units
I am looking at give up at around half a meter - unlike my 20 years old
unit that I wanted to replace (I need zero depth performance for inland
waterways). Does anybody know of a unit/brand/type that would work for me?
I'm not interested in fish, just displaying depth.

TIA,

S

I'm guessing they are all that way. Mine doesn't like it much less than 3
feet. They have to program it to wait a little bit for the return so it
ignores the initial ping. Even at the speed of sound in the water that
distance is covered pretty fast.

Which echo sounder is good up to (almost) zero depth?
 

On Mon, 09 Jun 2008 09:28:39 +0200, Salomon Fringe
wrote:

Hi all, I want to upgrade my echo sounder but I find that all of the
units I am looking at give up at around half a meter - unlike my 20
years old unit that I wanted to replace (I need zero depth performance
for inland waterways). Does anybody know of a unit/brand/type that would
work for me? I'm not interested in fish, just displaying depth.

With the newer digital units, you can degrade the sensitivity down
that the return ping is discriminated against the noise. Even the
cheaper units are 800 watt so you are dealing with power problem
decreasing the sensitivity would help a lot.

You will be hard pressed to find a single frequency transducers for
200 KHz which is what you are looking for - 50 Hz units are for deeper
water - more than 30'.

So, simply put, you need to find a digital unit where you can select
200 KHz and be able to decrease the sensitivity enough to get zero
depth performance. I have a Raymarine DS-500 that is selectable to
200 KHz or you can use the dual function and decrease the sensitivity
to find dead bottom.

The only other thing I would recommend is a single frequency depth
flasher which is different from a full sonar. Those work in a
different fashion and most of the new ones are 200 KHz which will give
you depth discrimination without having the mess around with menus.
Some are programmable, some aren't.

I wouldn't recommend anything specific because this is a special
circumstance and you have to fit your needs to what is available on
the market. Hope that helps a little.

Now, with respect to zero depth performance - pardon my ignorance but
I'm curious why you would be running around in zero depth waters. Do
you have a deep draft sailboat or cruiser of some sort?

Which echo sounder is good up to (almost) zero depth?
 

Salomon Fringe wrote in news:484cdba2$0$6032$ba620dc5
@text.nova.planet.nl:

(I need zero depth performance
for inland waterways). Does anybody know of a unit/brand/type that
would
work for me? I'm not interested in fish, just displaying depth.


You're asking for the impossible. The depth limit is determined by the
speed of sound and the pulse WIDTH (time) of the ping. A zero depth
would require a zero ping, which doesn't transmit anything. The other
problem is once the ping transmitter is shut off on a ping, it takes a
tiny amount of time for the receiver to come back on to listen for the
return from the ping, some latency is inevitable.

So, you want the shortest ping time unit with the fastest response you
can get to that ping.....and they're all about the same, mostly useless
under 2 ft. of depth, right where everyone needs it.

What I always thought we needed was a sort of underwater "curb feeler"
like we used to put on the pimpmobiles. A couple of stiff wires that
would protrude down into the water 3 ft from the BOW that would make an
awful griding noise like the curb feelers did through the hull alerting
us the expensive lower unit was about to be torn off by the bottom
rocks...while we're feeling our way along through the shallows....we
shouldn't be in in the first place.

The feelers would be spring loaded and fly back along the hull at speeds
above no wake speeds.

Just for reference, I find the depth sensed by the simplest of depth
meters so close to the bottom is much better than the "fish finders" with
their charting displays. But, the charting display gives you some
instant idea of whether we're getting shallower or deeper and how fast so
you can turn away or back....

Which echo sounder is good up to (almost) zero depth?
 

"Jim" wrote in news:g2j7hd$rer$1
@registered.motzarella.org:

http://www.mudbuddy.com/News%20&%20P...nformation.htm

.....like a trip back to Vietnam or Cambodia....(c;

Which echo sounder is good up to (almost) zero depth?
 

On Mon, 09 Jun 2008 11:04:13 -0400, wrote:


In a sailboat, the transducer would be mounted in the hull, above the
level of the top of the keel, so you would have 4-10 feet (depending
on how deep a keel you have) of water even with the keel scraping
bottom. Sounders usually have a "keel offset" setting to compensate
and tell you how much depth remains after the keel height is
subtracted.

I understand that - I'm not clear on the whole zero depth concept.

Which echo sounder is good up to (almost) zero depth?
 

On Mon, 09 Jun 2008 23:31:21 +0000, Short Wave Sportfishing wrote:

On Mon, 09 Jun 2008 11:04:13 -0400, wrote:


In a sailboat, the transducer would be mounted in the hull, above the
level of the top of the keel, so you would have 4-10 feet (depending
on how deep a keel you have) of water even with the keel scraping
bottom. Sounders usually have a "keel offset" setting to compensate
and tell you how much depth remains after the keel height is
subtracted.

I understand that - I'm not clear on the whole zero depth concept.

If the water's muddy and you can see the bottom that's the zero depth
concept or just use the acronym ZDC.

The sounder is the noise the hull makes scrapping in the mud.

Which echo sounder is good up to (almost) zero depth?
 

"Short Wave Sportfishing" wrote in message
...
On Mon, 09 Jun 2008 11:04:13 -0400, wrote:


In a sailboat, the transducer would be mounted in the hull, above the
level of the top of the keel, so you would have 4-10 feet (depending
on how deep a keel you have) of water even with the keel scraping
bottom. Sounders usually have a "keel offset" setting to compensate
and tell you how much depth remains after the keel height is
subtracted.

I understand that - I'm not clear on the whole zero depth concept.


The Navigator had a Raytheon system on it that was calibrated for the
transducer location versus the actual hull depth.
It was accurate to 2.8 feet. Ask me why I know.

Eisboch

Which echo sounder is good up to (almost) zero depth?
 

On Jun 9, 8:06*pm, "Eisboch" wrote:
"Short Wave Sportfishing" wrote in messagenews:f8fr44dh4d6e09iqlo00m3n5gf8993hnkq@4ax .com...

On Mon, 09 Jun 2008 11:04:13 -0400, wrote:

In a sailboat, the transducer would be mounted in the hull, above the
level of the top of the keel, so you would have 4-10 feet (depending
on how deep a keel you have) of water even with the keel scraping
bottom. Sounders usually have a "keel offset" setting to compensate
and tell you how much depth remains after the keel height is
subtracted.

I understand that - I'm not clear on the whole zero depth concept.

The Navigator had a Raytheon system on it that was calibrated for the
transducer location versus the actual hull depth.
It was accurate to 2.8 feet. * Ask me why I know.

Eisboch

The simple guess would be that your boat needed 2.9? Good to see
you stop back in.. We have all been working very hard to keep it nice
while you were away...;)