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Scanning Sonar Testing

(Svein H.) #41

All you need is rs485 to rs 232 converter and it is ready to be runned on a laptop. It will be sold with a converter and a pigtail. It you search me up un facebook you csn see the sonar on my page. Search for ‘Sogndalstrand Undervannstjeneste’

and you will find me.

Cheers

Svein H.

(Svein H.) #42

No, but out of what i can see of the spech. It is not wery good compared to what we use offshore.

Would like to test it, but have not have the chance yet.

Cheers

Svein Harald

(Etienne Demers) #43

Yes just received mine yesterday. I’ll have a play with it soon.

With regards to performance, got to stay reasonable for that price range. I think its pretty awesome :slight_smile:

(k.deboer) #44

Can’t wait to hear how your testing goes with that one Etienne.

(Etienne Demers) #45

I’ll keep everyone updated.

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(Svein H.) #46

Hi,
Have you tested the sonar? Very interrested in k owing how you think it performed?

Cheers
Svein Harald

(Etienne Demers) #47

Not yet. It’s mounted on but I haven’t had a chance to get everything up and running since I’m working on my mods right now.

Once I’ve got my SCU up and running, I will configure all the software including the ping.

I’m waiting to go offshore soon so I’ll be giving it a good test for 10 days. I’m sure I’ll have lots to say about it when I return :slightly_smiling_face:

(Etienne Demers) #48

Had a peak. Is it the one inside the buoyancy fairing?

How do you like the Blueprint USBL? Got a quote for it and I’m considering buying it.

Did you try their multi-beam sonar?

Nice boat by the way. I’m super jealous.

Cheers E

(Svein H.) #49

Thanks for that, looking forward to that. I am offshore at the moment and my latest investment is a Lowrance HDS live echologger and chartplotter with all kinds of scanning options from my boat. It is extremely accurate with higt resolotion. Will be more effective
to use this one to locate pipe and other things with in shallow water area.

Svein H.

(Svein H.) #50

The sonar is mounted in the tunnel from where the vertical truster used to be. I actually drilled out the bouancy to have it installed very tight and stabile.

Acc. the blueprint i did this test on behalf of the company that i am working for, Oceaneering and it was not accurate enough for our purpose offshore in the oil industry, but for me private i could like to have one because as long as i was not more than 50-60
meter of senter at 30m depth it was quite stabile. The boat is a nice boat made by a company in sweden called Ockelbo. It is not big, but it is ideally for my purpose. 21feet long and i can have it mobile on a trailer.

Can i ask for wht the quote was? I could get it from UK for approx. 7000 British pound.

(Etienne Demers) #51

Yes that was the price I got as well.

How inaccurate was it? Within a meter?

Oil and gas are very strict indeed but it’s just a big smoke show since I know from experience that survey positioning is never as accurate as they say it is even with the expensive USBL.

Did you try the water link underwater gps?

If so, how does it compare in accuracy with Blueprint?

(Etienne Demers) #52

Nice one, looks bigger that 21 feet.

I have this crazy idea to build a twin hull with bldc motors and use br2 tech to make it DP :joy: Have the ROV deploy from inside the cabin via moonpool.

So many projects so little time.

(Svein H.) #53

I it not within one meter, but that is not what we need eighter. As long as you see related to the map where you are and where you are heading when flying the rov you have the tools to get in right potition i think. It depends how far away you are with the
vessel related to the Rov.

When it comes to DP i am actually playing with that posibility with use of a front eletric motor with GPS, this one can be controlled from my Lowrance HDS live screen. Search for MotorGuide and you will see how you easely can get DP :+1::blush:

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#54

I’ve also used a Blueprint USBL, I’m still hoping to make it work better (I’m in contact with their support). For now the position error (rough estimate) is around 20m with a distance between the boat and the ROV being between 50 and 200m. It seems to be quite sensitive to noise in the water.

About DP (must be so great to have this !), if you need a high precision GPS, I’ve tested the RTK-GPS from Drotek, it works pretty well ! I use two https://store.drotek.com/DP0503 along with two Raspberry Pi and 4G communication. Depending where you want to use it another communication mean would be better.

(Etienne Demers) #55

Hello Benji,

Thank you for your feedback.

20m is pretty bad in such a short range.

Did you calibrate for sound velocity?

I was thinking about giving this one a try: https://emlid.com/reach/

Cheers,
E.

(Etienne Demers) #56

Just following up on this.

I am presently offshore with my BR2 and have the ping installed on the back.

I find that it does a fair job at about 4 meters off the seabed.

I also get a lot of false readings. The beams may be a bit too wide. I do not know.

I’ll run some more tests when I have a chance.

Considering the price, I am quite happy with it. In the end, I only use it so I do not crash on the seabed and 4 meters is enough warning for me.

Cheers,
E.

(Svein H.) #57

Thanks for that, but my questions was regarding the Tritech 720im. I just finished the installation of the ping altimeter today without any problem, but find it not very accurate. I can stay 20cm above seabed for several minutes and it read 4-5 meter, and suddenly it drops down to the depth i actually is on. Have not been able to do any calibrations on it and not aware if there i options for it.

Can you @jwalser tell us what to do to make it more accurate? i have several logfiles from today if you want to have something to look at.

Cheers
Svein Harald

#58

Hello Etienne,

Thanks for the suggestion. I asked the supplier if I should modify the speed of sound setting, he said there shouldn’t be any need to touch this. But I’ll try next time as from last time measurements I have a strong impression that the speed of sound is off (part of the error is clearly dependent on the distance and doesn’t look random).

I also came accross this one, looks great ! I chose the Drotek as it is less expensive and I didn’t need the IMU, WiFi, housing etc. as I wanted to use it with a Raspberry Pi.

(Etienne Demers) #59

This is an odd response unless their equipment measures the sound velocity by itself?

I am no positioning experts but I have been working offshore a lot with several types of USBLs and the survey department usually do several SVP (sound velocity probe) dips per week to maintain accuracy.

Since speed of sound is used directly to measure distance underwater, this will influence the accuracy for sure.

(Rusty) #60

Hi @SHS,

The Ping’s minimum range is actually 0.5m, so we don’t expect it to work well at 20cm as you describe. It’s challenging to pick out the depth at that range, unfortunately.

-Rusty

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