Humminbird 987c SI side-imaging sonar...anybody got one?

[Chagy]

Would you need both things or the sub-bottom profiler will do the same as a SSS plus it will let you see under the sand.
Or are they two different things the SSS to see on top of the sand and the sub-bottom to see under.

All the best,

Chagy..........

 

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[rgecy]

No, you would need two different units.

The side scan looks out to the side and sends an image of objects that are above the sea floor. The sub-bottom profiler looks directly down in a narrow beam and sees what is directly beneath the transducer under the sea floor.

I have heard where some surveys are performed towing all three devices in an array. Basically they tow a mag, then behind it a sub-bottom profiler, and behind that a side scan sonar. This way all data is collected in a single pass. There is software package that handles all the incoming data.

Robert in SC

 

[Chagy]

can you run to mags at the same time or one will be enough?

Chagy.....

 

[rgecy]

You could run two mags at the same time. There is actually a setup that uses three Cesium mags. They use outriggers to tow basically a triple gradiometer setup. One left, one right, and one in the center. A computer logs the readings and can actually determine where an object is in relation to the mag (left, right, or directly under) based on readings from each mag. An object will have a greater reading on a closer mag and a smaller reading on a mag further away. It greatly increases the sensitivity. Virtually no iron object will go unrecorded!

Here is a picture of Deep Blue Marines survey and recovery vessel, R/V DeepScan pulling this same setup.

Robert in SC

 

[Peg Leg]

Here is a DUMB question.
My cousin has a Fish Finder on his fishing boat. It looks like a small Side Scan Sonar. He can see fish at 8 feet or more and he has a GPS attached with a printer. What is the difference except for the cost?
Peg Leg

 

[rgecy]

PegLeg,

You will have to be more specific. I have no idea what the difference is without knowing what unit you are talking about. Is it a Side Scan Sonar made from a fishfinder or a fishfinder that has side scan capabilities? What unit does he have?

Robert in SC

 

[Chagy]

Rob,

How big is that boat on the pic? How many feet?

Chagy...

 

[rgecy]

Chagy,

60 feet! I got a chance to check it out first hand down in Key West. Pretty cool! I dove with Oldman (Ed) on one of Deep Blue Marines sites off Woman Key and got to see some of their latest finds. We only did one dive before we had to head up to Marathon. Vis was only about 6-8 ft and the current was ripping through Hawk Channel. It was a great trip though!

Robert in SC

 

[Chagy]

Chagy,

60 feet! I got a chance to check it out first hand down in Key West. Pretty cool! I dove with Oldman (Ed) on one of Deep Blue Marines sites off Woman Key and got to see some of their latest finds. We only did one dive before we had to head up to Marathon. Vis was only about 6-8 ft and the current was ripping through Hawk Channel. It was a great trip though!

Robert in SC

Sounds like a great trip! I didnt see blowers on the R/V....do they take them off and put them on when needed?

Chagy......

 

[rgecy]

No it doesn't appear that there is a blower in this pict but yes it does have one now! It also has a 8" dredge. The screening/separation table is located on the bow and from what the guys have said works great.

Robert in SC

 

[FISHEYE]

heres a pic of the r/v deepscan blower,i tried to post all the specs on the boat earlier but it got messed up,ill try again later today

 

[rssharpetx]

Scuba,

You got the main point and problem. This particular record was taken with 5 differant frequency transmitted at the same time 3.5khz, 12khz,24khz,50khz and 200khz. The higher the frequency the shorter the wavelength the better the resolution. On the other hand the lower the frequency the better the bottom penetration but "blurrs the record" This is why we use so many frequency etc. They are combined in software signal processing to produce the best of both worlds......so goes the theory. Conventional chirp sonar sweeps threw a frequency band and is then processed so you get fractional wavelenght thus better resolution.....this is great in deeper water but in shallow water since you transmitted a longer pulse or sweep you get interference with shallow water data being overburdened by out going transmit pulse and many other problems, surface ghost, bottom multiple etc. I use this particular system for sediment, pipeline type surveys. We did find some ballast piles on a couple of projects. Used side scan etc after plotting the site. It is yet another tool for the tool box!

Best Regards

Scott

 

[ScubaFinder]

Thanks Scott, that is where my head was going, just hadn't put it all together yet.

Robert / Chagy,

There were pics of the screen separator on Deep Blue Marine's web site, but I can't find them now...if you have them could you send me a link? The Deep Scan is a well thought out boat, and I bet it's pretty effective too! I'm jealous Robert! Here's the boat specs http://www.alldeepblue.com/DeepSCAN.pdf

Jason

 

[Peg Leg]

PegLeg,

You will have to be more specific. I have no idea what the difference is without knowing what unit you are talking about. Is it a Side Scan Sonar made from a fishfinder or a fishfinder that has side scan capabilities? What unit does he have?

Robert in SC

I believe it is a fishfinder with side scan capabilities. A friend of his put the thing together for him and the total cost was around $800 including the fishfinder.
Peg Leg

 

[Peg Leg]

Oh I might add that he will sell me the unit at a discount but I have to see it work first and I have just the place to test it
Peg Leg

 

[rgecy]

They may have one of Burton Electronics model. They use a custom built transducer and towfish that feeds into a Lowrance or Eagle fishfinder. Its a cheap alternative and gives excellent results, but it only looks to one side.

Burton Electronics Website

Some have also tried to build a side scan from just an ordinary fishfinder and an array of puck transducers mounted on a towfish.

Heres a website: Dan Fountain's Homegrown Side Scan Sonar

Check it out! I made one of Dan Fountains using an old Lowrance X-16 paper chart recorder. It works, but nothing like the Humminbird 987 or Burtons Side Scan.

Robert in SC

 

[ScubaFinder]

So Robert, I have been looking into the Burton site as well. If you were going to start from scratch right now, which product would you go with? I'm toying with building a Burton unit from the T6-200KHZ unit and purchasing a nice fish finder, or just getting a Hummingbird 987c SI and building a towfish for it. Any advice or recommendations?

Thanks,

Jason

 

[Darren in NC]

After seeing the images of both, I'd go with the Hummingbird. That's only based on clarity, though. There may be some depth advantages I'm not aware of.

 

[ScubaFinder]

I'm kinda leaning that way right now aslo. I talked to Mr. Burton (Gary I think?) today, and he was anxious to sell me one of his units. I forgot to ask him about hooking it up to a PC though, and it looks like the Hummingbird unit has a port all set up for that. I think I'd rather be able to view and capture on the PC myself, and those 987 images do look sweet.

Robert, we need an update on that Towfish

Jason

 

[Salvor6]

The Humminbird has a port but it is for an SD card to record images. You can't hook it up to a computer. Why would you need a towfish? There's a 987 on ebay right now for $1699.