Need side scan sonar/ Humminbird?

[Tejon]

Hello everybody,

I am from southern Germany and I was thinking about treasure hunting in the nearby lakes to locate little boats and small containers.
I am very new to side scan sonars so I would appreciate your help.

My intention is to operate from a very small boat, a rowing boat at times.
Would you recommend the Humminbird 997c or do you think a less newer unit will also do it.
Can I operate the gear with batteries?

Generally speaking, what kind of equipment would you guys recommend me?

Best wishes, Chris

[Rickard]

Hi Chris,

To answer your question with confidence one would have to know more about the conditions in your waters, especially depths. But a fair guess is, yes, a 997 would definitly do the job. There are not so many "old models" yet since this type of instrument were presented for the first time only a few years ago. The 987 and the 981 and the various 700 models with SI will also find containers and small boats, provided it's not too deep (more than about 40 m). The imaging capacity differs very little between the models. The newer models can run at 800 kHz but that frequency seems useful only in very shallow water. All the Humminbirds can be run on any 12 V battery. I use a small, cheap 7.5 ah lead-acid battery, it can keep my 981 going a whole day. If your boat is very small it could pay mounting the transducer on a towfish to reduce the disturbancies from wind and waves.

Wish you good treasure hunting!
Rickard

[Stefan N.]

Chris,
in my opinion / experience those devices are really just "shallow water devices". If you want to search beyond 30 m depth you need to go down with the transducers, which means a professional SideScan with a tow fish.

Schöne Grüße aus Österreich / Traunsee ;-)
Stefan

[hertsog]

for a little deeper scan i made a towfish to humminbird:
http://meelis.pri.ee/diving/sonar/index.html
cable length is 30m. If supply voltage at least 13-14V, then no significant signal loss detected.

[Stefan N.]

Humminbird tow fish

for a little deeper scan i made a towfish to humminbird:
http://meelis.pri.ee/diving/sonar/index.html
cable length is 30m. If supply voltage at least 13-14V, then no significant signal loss detected.

That's quite interresting!
How deep can you scan with this device?
At my actual project I've a maximum depth of 100 m.

Do you've some images already produced with this "tow fish" ?

Regards
Stefan

[Rickard]

Depth capability

Hi,

100 m is awfully deep for the Humminbirds! You will definitly need a towfish and a very long cable. In my present system I use 50 m shielded ethernet cable with individually shielded pairs, not HB extensions, and I get good results down to 45 m using a towfish. I tested once with 100 m UTP and got results but the attenuation was strong and there were significant problems with crosstalk and interference. These issues have been discussed since long at this place: http://www.xumba.scholleco.com/index.php and also here: http://forums.sideimagingsoft.com/. You will have to do some searches at those places to find all relevant material.

Regards,
Rickard

[Tejon]

Thanks guys for the helpful advice.

If you say that the 700er devices, for example the 798 also does the job, it is fine with me. I am only into the sonar function.
I would only operate in shallow water between 5-30 meters since my diving experience is not that sophisticated and I also want to see what I locate, not only on the screen .

Do I understand it right, that only the things which stick out of the mud appear on the screen. Everything in the mud is not visible, right?
And do you guys think the US-Version will be suitable to operate in Germany. Because buying from a German supplier would be almost twice as expensive than buying from a US dealer

@Stefan do you have experiences with a Humminbird in our lakes you could share with me?

Gruss von Bayern, Chiemsee

[Rickard]

At the frequencies used in the Humminbirds, 455 and 800 kHz (some systems have 262 kHz but the resolution is too low), nothing below the mud surface can be seen. At lower frequency, 200 kHz and lower, several meters of clay can be penetrated, at least when the beam is directed towards the bottom. This can be seen in the 2D-view which uses low frequencies. A low-frequency sidescan can see things in the mud, but not very deep and the objects must be very "hard".

I don't know what happens when US units are operated outside the US. I think you can find the answer in the forums I suggested. US-models are called "domestic" and non-US models "international".

Regards,
Rickard