Second OpenROV dive, first wreck dive!


#1

It was such a calm sea and lovely weather yesterday, we took the OpenROV out to dive a wreck. We’re very lucky to be only about 2 miles by boat from the wreck of the SS Breda, one of the UK’s most interesting wrecks. It is a huge site and we saw a tiny corner of it.

There is a lot of information about her, a large ship lost in 1940 to German bombers.
http://www.lochalinedivecentre.co.uk/?page_id=1314

It was only our second dive and the most unnerving thing is that, once the ROV is in the water and below a couple of metres, you’re flying blind, no idea where you are, until you see something ahead, or hit the bottom.
We went down about 20-25 metres and then suddenly, there she was. For all I knew, we could be dropping right down into one of the holds and ready to get tangled at every turn.

So far, I’ve found that it doesn’t descend or ascend very well, and when you go forwards it also dives. I’m sure it’s just a case of practice, also I think keeping no slack in the tether will be safest.

We did a few minutes, then got too scared and came up, but it was very exciting.

Any advice on retrieving a tangled ROV would be good - before it happens!

Here’s a little flavour of it.


#2

So cool! Can’t wait to see more!


#3

Thanks Brian. It was very scary!
Did you see my other post about uneven motors? The control doesn’t seem to be as predictable as I was expecting. I wouldn’t fancy my chances steering out of an enclosed space.

The “Dead Man’s Fingers” look exactly like that, don’t they?

We’ll definitely be going back there as soon as I’ve installed a compass.

Andy.


#4

Beautiful footage!

Wreck diving is always exhilarating but also unnerving, I highly highly recommend getting neutrally buoyant (or at least positively buoyant) tether to make sure it doesn’t sink down and snare itself on obstacles. For a DIY approach, you can attach fishing bobbers to the standard OpenROV tether to make a DIY neutrally buoyant tether. We should be getting neutrally buoyant tether back in stock soon in the OpenROV Store (the stuff works wonders, and can handle a 300lb load!)

If you know the coordinates of the site you want to visit, You can drop a diving shot to help you descend and ascend to the same location. It is really useful to have a visual guideline down to where you think you should be going.

For retrieval if a ROV get tangled, follow your tether back out to minimize the chances of wrapping it on anything. Oftentimes pulling on the tether from the top will just limit the vehicles ability to move and ensnare it more. Always first get a visual on the tether and try to pinpoint where it is snared. Sometimes it is just caught around a corner, and dragging the tether back out the way it came will untangle it.

The key trick for saving a tangled ROV is to try to never get tangled :stuck_out_tongue: Go slowly in environments which might ensnare the vehicle, and scan for obstacles and objects which might pose a threat. Give yourself as much distance as possible, and keep in mind that the tether is coming off the vehicle in the direction from where you deployed it.


#5

Hey thanks Colin.
The tether sounds like a great idea but sadly we can’t afford 400$, the ROV cleared the bank account out!
I will investigate fishing floats, it might even serve as a depth indicator as well if we put one every metre.
Thanks for all the advice about avoiding tangles.
One question you may be able to help with. When I go forwards, it also dives, so is quite difficult to position accurately. Is that because the weights make it slightly nose down or is it the way the motors are positioned? I would like to adjust it so that forward really means forward.
Thanks.
Andrew


#6

Very interesting impressions. Great work, Andrew!

I struggle with this too and i think it is combination of both, the nose facing down and the hydrodynamic flow around the asymmetrical ROV that creates downwards drag. On possibility is using the depth hold from the IMU (which is not available for you right now?), or manually going up slightly during a forward movement. Also for me, adding a tiny floater to the front, helped. (In field i simply taped a small piece of wood to the front bar).


#7

Thanks.
That’s a good, simple idea, just adding a little buoyancy to the front, I will try that.
Do you have the IMU fitted? I would like to get one but the shipping to the UK is 66$, crazy!
Where have you dived? Do you have any video?
Andrew


#8

Yes, I ordered one right from the start and it is a superb piece of technology. It is extremely tiny, but still delivers excellent data about the ROVs positioning. I don’t understand why the shipping is so expensive, it is very small package. (Maybe someone from the OpenROV-team can help?)

So far I only accomplished two smaller test dives, but the visibility was so bad (I am still looking for suitable and interesting locations near me), that you really could not see a thing (despite anything worth uploading :slight_smile: ). I did those dives using pretty much only the IMU for navigating.

How do you extract the pure video stream for your upload?


#9

@Fe3C thank you for the compliments on the IMU/Depth Module :smile:

We have worked with @e4andy through email and figured out a more reasonable shipping cost.


#10

Excellent! Love the team for being so flexible! Looking forward to more videos from Andrew’s IMU supported ROV :slight_smile:


#11

Hi Lukas.
They have been very good, I ordered an IMU last night with just $6 mail. It will take a little longer but I don’t mind that.

We are so lucky here with locations. We have several wrecks within a few miles and some very deep water, it often gets to 50-60 metres deep within half a mile from shore. As we approach winter, I think the water will get clearer, but unfortunately my boat needs to come out for winter storage soon.

Regarding the video, I just did a screen capture with Screencastify (with the heads up display off) then cropped it in Final Cut Pro. The resolution would be better if there was a way of extracting the video stream.

Maybe Brian knows.

Andrew


#12

Brian, thank you very much. I ordered the IMU last night with Nima’s help. Strangely, we use the Bosch 9 axis sensor at work, but it is going to be much easier interfacing yours.

Do you know if anyone has come up with a protocol for dead reckoning using this powerful sensor?
Thanks
Andrew


#13

The raw video stream has its own port address. You can get to it by going to http://openrov.local:8090/?action=stream (assuming you are running software 30.0.3)

From here you can record it using software like VLC.

Be aware that this is causing two camera streams to be open at the same time, putting more of a load on the BBB in the ROV.


#14

Very helpful, thank you @Brian_Grau Is there any document or so that collects all these “insider-tipps”? Something like an Advanced Operators Guide. I feel like a lot the potential of this platform is hard to find :smile:


#15

@Fe3C Funny that you should mention this. I am actually working on a new Operator’s Manual right now which has a Community Tips section with topics like this.

We also have the Community Hacks section on our documentation page.