Marine Debris Collecting ROV V2

Hi All

Last year I cobbled together an ROV which wasn’t much more than a rough sketch of what I thought at the time a marine debris collecting ROV would look like. I attempted to incorporate too many different capabilities into and ultimately compromised the capacity of any individual capability so I have gone back to a more basic design with just three primary tools on it. This ROV is aimed mostly at retrieving items such as shopping trolleys, bicycles and other assorted items that village idiots the world over throw off jetties, river banks and bridges. The grappling hook detaches and has a 200 kg breaking strain line 50 metres long with a float on its arm so that items can be hauled in without the ROV being further involved.

The ROV also has a quickly demountable twin disc cutter with counter-rotating blades with hopefully the ability to cut through rope, discarded fishing gear and possibly light cable. I am yet to find just how long an M200 can put up with that kind of load. There is obviously plenty of testing to be done to further refine what works and what doesn’t work.

As you can see, it has a Cerulean sonar and DVL650 on it although the sonar will probably only be able to see much larger items.

For those of you that are interested in the design of the body, I designed two very simple boxes that couple together with flat hatches. The ROV won’t be needed to go deeper that 50 metres and I wanted to keep the design as simple as possible to keep the machining cost down. I prefer having my electronics be accessible to me easily and have found getting 10 ESCs into a 4” tube difficult in the past although the larger tube sizes would make that much easier.

My normal designs focus much more heavily on making the bodies as hydrodynamic as possible but the idea was to make this as cheap as I could to allow entities involved in marine debris collection to have the cheapest units possible.
Cheers

John






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Wow - that looks amazing John :+1: , particularly the compact form factor but with heaps of space for electronics. Are the enclosures and frame all aluminium? I’m certainly no expert but does the limited separation between fwd and rear vertical thrusters limit power for pitch? Also found that the Cerulean Omniscan can return a useful signal at less than the advertised minimum 6m range. Although blurred and prone to artifact depending on the object characteristic its is interpretable and suspect it’s enough to ‘see’ larger objects until you are close enough for a real visual in the murkiest conditions.

Hi Bill

Glad you like it! Great to know the sonar is capable of picking up items at close range. I think I will be highly reliant on it in most coastal river systems the clean-ups take place.
The body is machined from T6-6061 alloy, the same alloy that all the BR tubes are made of.
Even though there is the forward and rear vertical thrusters are close together, I have had no problem with adequate pitch in previous designs with them that close together. I like having them tucked in close to cut down drag that you get on a larger body where they are spaced further apart.

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Really nice robustness/durability for a hard-working ROV and ease of acessing the enclosure contents a game changer. Will get in touch directly to see if we can organise a demo!

Hello @johng !
Very nice ROV and very interesting tools you designed.
Have you tested it already? How did it perform? At what depth did you test?
I’m interested in having more details on how you managed to seal the electronics and battery enclosures.
Thank you!

Hi Fernando

Thanks for the interest. I haven’t tested in to anything other than pool depth at this stage but am confident with the 4mm wall thickness increasing to 10 mm thickness at the ribs spaced 100 mm apart on the wtc and hatches that it will be perfectly ok at a max of 50 meters. I have just one 5.33 mm cross section o ring but I design my hatch cavities to be tapered inward at 2 degrees so that I have a full metal on metal contact when the hatch is bolted down flush. This has worked very well for me in the past so I have confidence it the seal. It would be interesting to know at what depth it actually does fail at but I am not going to sacrifice a wtc and hatches to find that out when the intended use of this machine is in depths of less than 50 meter.
The tools are a work in progress and further testing will no doubt result in numerous modifications. That is always part of the process of developing any new system, or at least in my experience.
cheers
John