Deep dives

Spot for your general beginner questions.
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duncan
Posts: 22
Joined: Nov 6th, 2013, 5:43 am

Deep dives

Post by duncan »

Has anyone ever built an ROV to go as deep as 60m? Or over 100m?

~120m is my ultimate goal (a specific wreck in mind) so I'm interested to know from anyone experienced with these depths what approaches just won't work.

For instance, would a steel housing withstand 100m depth? If not, what would?

How about the plexiglass in front of a camera? Can you just layer the plexiglass and tightly bolt it together to improve its strength?

Is filling the hull with oil essentially a necessity?

Do you need specialised thrusters?

I'm getting to grips with the basics using this forum but realise at deeper depths there is a whole other host of issues, and much of the material on the forum most likely doesn't apply
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ROVER3D
Posts: 128
Joined: Nov 9th, 2012, 7:45 pm
Location: Wuppertal, Germany

Re: Deep dives

Post by ROVER3D »

I've reached 65m meters for an expedition at Elba, Italy with ROVERII. There are many things i've learned about this depth. First of all: You need lights, powerful lights! Else you need enough thrust to pull the tether!
For me using oil-filed housings is the best way to forget pressure-problems. Only have to look for a pressure-stable camera-housing. With oil-filled housing there will be no leaking-problems with saltwater. But dont forget a oil-pressure-equalizing system!
duncan
Posts: 22
Joined: Nov 6th, 2013, 5:43 am

Re: Deep dives

Post by duncan »

I am thinking filling with mineral oil is practically required.

So the camera housing can't really have oil filled in it since it would mess up the picture. Does that mean you need to pay a bit extra for a depth rated camera? Unless you mean there are tricks I'm not aware of
sideshow
Posts: 4
Joined: Dec 12th, 2013, 10:05 am
Location: Norway

Re: Deep dives

Post by sideshow »

Great topic! I have plans for building a deep water ROV too.
Thinking of around ~100m with a specific wreck in mind here aswell :)

No great plans for my ROV so far, just done some thinking and research.
Was thinking of using a dome for surveillance cams and a PVC-pipe as body but it might be hard to get a tube like that waterproof down to such depths...
fryslan76
Posts: 290
Joined: Dec 18th, 2012, 4:52 pm
Location: Netherlands

Re: Deep dives

Post by fryslan76 »

Hi,

No personal experiance with a ROV on this depth, only with scuba diving. The wall tickness is not the problem, seals are. So look how camera housings and such are made for scuba diving to see good building practice for this depths.
In the Netherlands there are PVC pipes for gas lines which are rated to 10 bar pressure (internal) I am planning on using these to make my body. The problem I for see now is deforming due to pressue of the pipe which you should be able to counter with an internal strut.

Regards,

Fryslan76
MNDeepROV
Posts: 34
Joined: May 12th, 2014, 3:46 am
Location: Minnesota

Re: Deep dives

Post by MNDeepROV »

ROVER3D wrote:I've reached 65m meters for an expedition at Elba, Italy with ROVERII. There are many things i've learned about this depth. First of all: You need lights, powerful lights! Else you need enough thrust to pull the tether!
For me using oil-filed housings is the best way to forget pressure-problems. Only have to look for a pressure-stable camera-housing. With oil-filled housing there will be no leaking-problems with saltwater. But dont forget a oil-pressure-equalizing system!

Question on your above comment on oil-filled housing. Which housings are you referring to? Which would you NOT want to fill with oil (Lipo compartment, etc.). On another forum someone mentioned not filling the electronics with oil for various reasons (I'd rather not).

Also, you mention an oil-pressure-equalizing system. Can you elaborate on the need/specfics?! Much appreciated.

Currently I'm planning on using either an aluminum cylinder housing, if I can find for a reasonable price, or Schedule-80 PVC. For my depths (300') I beleive that will be appropriate.
rovdude
Posts: 83
Joined: Sep 17th, 2012, 10:28 pm
Location: Baltimore, USA

Re: Deep dives

Post by rovdude »

On another forum someone mentioned not filling the electronics with oil for various reasons (I'd rather not).
There may be reasons I am unaware of, but I got to go to Northrop Grumman and they showed us how they work with AUVS(Some seriously impressive stuff too). They actually do fill their electronics compartments with oil.
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TigerShark
Posts: 108
Joined: Jan 7th, 2014, 2:43 pm
Location: Washington State

Re: Deep dives

Post by TigerShark »

I plan to go to over 900' and this should be fine with an air filled pressure hull. I will use uncased brushless motors and cat 5 as a tether. You do not need to have an oil filled housing unless you are going really deep >3000' or so. Just design a good pressure housing. Most observation class ROV's are air filled.
MNDeepROV
Posts: 34
Joined: May 12th, 2014, 3:46 am
Location: Minnesota

Re: Deep dives

Post by MNDeepROV »

Thanks for the input TIgerShark. 900' is a fantastic goal! How far have you made it so far? I've been looking at using Schedule 80 PVC for my Hull...great pressure ratings...but was bummed to find out just how expensive the fittings are. I was also going to make a hydrostatic pressure chamber out of the PVC too, but at $100 for a 8 to 12 inch cap alone, well that's pretty ridiculous. Now I'm looking at steel options.

Also, been looking at aluminum tubing dependent on price and final hull size in my design (still finalizing that). Looks like you've got metal hull. Aluminum? Working well for you? I'd be curious as to how you sealed it. I've been thinking something along the lines of the Nemo 200 camera housing shared on another post.

I may just revert to Schedule 40 PVC because it does actually hits my goal depth...but just at the max operating pressure ratings...and then I can go no further.
kendelrio
Posts: 11
Joined: Oct 22nd, 2013, 9:37 am
Location: Alexandria, La

Re: Deep dives

Post by kendelrio »

rovdude wrote:
On another forum someone mentioned not filling the electronics with oil for various reasons (I'd rather not).
There may be reasons I am unaware of, but I got to go to Northrop Grumman and they showed us how they work with AUVS(Some seriously impressive stuff too). They actually do fill their electronics compartments with oil.

We fill the majority of our housings with oil also. That said, our electronics bottle (boards etc) are machined aluminum with a depth rating of 15,000 fsw. Personally I have dove the sub to ~9700 with no issues on our oil compensated or 1 atmosphere bottles.

Good luck!
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