During the summers [Doug] has been building a 75 foot sailing junk to be launched from America’s most inland port. When Oklahoma’s winter hits he heads indoors to work on an ROV that will prowl 3,000 feet below the surface. Originally building a piloted submarine, he grew bored and decided to use the sailboat as a carrier for his fleet of remote submersibles instead.
A consummate amateur, [Doug] is the first to admit how little he knows about anything and how much he enjoys the open source spirit: collaboration, cooperation and learning from others. Determination and hard work fills in everything in between.
Hackaday covered the beginnings of his ROV last winter. In the year since it has progressed from some sketches and a 10″ steel pipe turned into a pressure testing rig to a nearly-complete, 10 foot long, custom-lathed 4″ aluminum torpedo laying on his shop table. In a bow-to-stern walk-through [Doug] shows how he is building science equipment for less than a penny on the dollar by using largely off-the-shelf imaginatively-repurposed parts or things he could fabricate himself with only a lathe and a 3d printer.
Continue after the break for a breakdown of the tech used.
The body of the ROV alternates between wet (flooded) and dry sections to preserve balance. Surprisingly, the multitude of thrusters on-board are plain RC outrunners most of us would recognize from quadcopters – apparently with a little potting they are not overly harmed by immersion in salt water. Ditto for the LED banks which lack any heat-sinking, relying on exposure to near-freezing seawater for cooling. Dry sections are stuffed full of all manner of gear: a complement of HD IP cameras, RC LiPo (11.1v, 6Ah each) packs, motor ESCs, external & internal pressure sensors, humidity sensors, an inertial measurement unit and relay banks all controlled by an Arduino Mega with an ethernet shield.
The pride and joy of the electronics are an affordable pair of Lowrance sonars for ocean bed mapping, commonly used as fish-finders. He chose the model he did because the board can be collapsed smaller, making it easier to fit into a pressure vessel. Each sonar board is connected to a transducer, one side-scanning and one spotlight facing forward. These display up on the surface what the terrain looks like 150 feet away in the pitch black.
Unexposed wiring having to traverse a between dry sections is handled by brass hose barbs and sealed inside vinyl aquarium tubing. The pressure through the wet section crushes the tubing tight onto the wires. For exposed wiring, [Doug] has come up with own solution of centrifugally packing epoxy into plumbing fittings fitted with connection pins for a 2,600 PSI seal.
The ROV maintains a data connection to the surface with a simple, slightly-buoyant Cat-5e and polycord tether. 5000 feet of cord is too long of a run for household hardware so [Doug] has mounted ordinary Startech VDSL2 extenders which also reduce the wiring requirements down to a single twisted pair (3000 feet yielded 46MBps and only 2ms lag). A bigger issue are the HD cams themselves which they found to be rather jello-like anywhere near HD performance.
When his carrier ship is finished [Doug] plans on sailing around the world, exploring the depths and doing meaningful science into retirement. He figures his $5,000 ROV will match ones sold for $1,200,000. For research projects that puts his open source ROV design in the realm of disposable relative to operations costs. For him it means he is able to own one at all.
All of [Doug]’s videos regarding both his sailing ship (with an ubiquitous $250 schoolbus diesel engine as a backup) and his ROV are superbly filmed, cut and edited. Camera angles change quickly enough to stave off boredom and show both scale and detail of the work. It is easy to spend hours watching how he overcomes each obstacle and budget hurdle.
Ever the collaborator, [Doug] is calling out for anyone who wants to stop by for a visit to work on the boat or to participate in the ROV build with advice. His videos regularly feature collaborators who travelled to help. If you feel you have something to contribute, he seems welcome for assistance.
This reads rather weird: “During the summers [Doug] has been building a 75 foot sailing junk to be launched from America’s most inland port.” ?
I’m guessing you’re confused by the term “junk”. A “junk” is a type of sailing ship. http://en.wikipedia.org/wiki/Junk_%28ship%29 <– You would recognize them by sight, if not by name.
Also, Tulsa, Oklahoma has a river that leads to a river that leads to the Mississippi which leads to New Orleans which is on the Gulf of Mexico. Hence, guy building a giant boat in his back yard in Oklahoma can actually sail it out to Atlantic.
Doug is a person.
Summer is a season.
Lol, Correction, Doug is a metal working genius. That junk would be so much cheaper and easier to fiberglass, however matching the strength of 1/2 inch plate would be twice as heavy. Its a junk tank.
I’ve been following Doug’s build for well over a year now, and he’s definitely not a metal working genius, and expresses that many times. you’ll even see the chicken decal on his welding helmet because he does “chicken shit welding”. Fiberglassing means building a mold out of wood, and spending many months laying layers of glass. Doug knew how to metalwork, and as most cruising/live-aboard books will agree, it’s better to know how to repair your own boat than have one that’s cheaper/lighter/faster. Steel sailboats are still incredibly popular due to the easy of repairs, the DIY nature, and the robustness of the hull. Junk refers to the type of sailing rig. Check out Chinese Junk rigs. It’s preferred for most cruisers because it’s cheap and easy to maintain, and is very easy to sail in nearly all sailing conditions.
What kind of Modems are those? I was not aware that they could be used like this. (I always thought there was something special on the telco’s side) How are they set up to connect to each other? That is pretty cool!
direct modem to modem? http://www.jagshouse.com/modem.html
That doesn’t work. It would work with a 56kbps analog modem, but not for VSDL. The thing he uses is specially designed to send ethernet over telephone lines as a cat5 replacement. In theory it is not very different from a VDSL modem, but the firmware is different.
It is possible with some very specific models of modems. Especially SDSL (symmetric DSL) modems often support this.
Various types of DSL modem can run back-to-back, no DSLAM needed. This type is commonly used with old installed wiring, where you’ve got vintage twisted-pair running all over the place, and sneaking a few megabits down it will obviate the need for new wiring, at least for a few more years.
Regular POTS modems can also run back-to-back, if you provide loop current. It occurs to me that a lot of this generation’s hackers might not be familiar with some of the things we thirtysomethings found obvious, so maybe that would be a good subject for a future post…
Yes, a POTS modem tutorial would be great since there’s the possibility of sending data over the main power line where POE won’t overcome the resistance of a long umbilical. Umbilical properties are one of the expensive/frustrating bugaboos of ROV design. An observation or working class free swimmer needs a scope of 3:1 – 5:1, a towable needs more like 7:1 – 9:1 to avoid bad harmonics and the need for a complex suppressor. Two copper wires for power and slow data would keep costs down for that 20,000 umbilical needed for 3,000 foot target depth in the case of this very impressive project.
This piece explains a bit about scope as it relates to anchoring, I will put something together for scope as it relates to ROV’s soon. http://maritime.about.com/od/Glossary/g/Correct-Scope-Is-Essential-For-Safe-And-Comfortable-Anchoring.htm
He is limited to 5,000 feet of cable. Near the end of the video linked he shows how he’ll get 3,000 feet of depth from that by using the dive wing on the ROV to force it down.
The use of the dive plane (wing) to force it to depth will make the scope ratio horrible and the mostly vertical umbilical will hum like a guitar string at just a few knots. Matt didn’t give me an option to reply directly to him and didn’t take the time to think about why scope is important. An ROV umbilical needs a significant scope ratio to keep the vibration to a minimum. The natural curvature of the line creates a horizontal section right before the ROV that dampens vibration from the more vertical section that will eventually cause mechanical failures; usually of the termination hardware.
I have 1200 hours of open water time operating my machines and a couple thousand more in tanks and sims. I know what breaks, and a towfish forced down with planes is bad for everything from the pressure hull to the capstan. It’s too bad the writer is so defensive of his basic understanding since this is a fascinating project built by an interesting guy. From Matt’s other comments it seems like he just wants to argue with people. Maybe the editorial staff could review the HAD philosophy with him.
Paul – No conspiracy. The reason you weren’t “given the option to reply directly” is because Hackaday has a max depth of 5 nested comments. This is true of any post, including your own, not some attempt to prevent you from speaking your mind.
I’m not defensive of my novice-level understanding of ROVs, nor defending the design from the article. I watched about 10 hours of video for the article, and just thought I’d be helpful and reiterate Doug’s explanation since not everyone is going to dig for those answers. Nowhere did I say you were wrong, nor that Doug’s solution was superior. I have no experience or knowledge to evaluate one method versus another. Just giving the context mentioned in the source material for why he was limited on the tether and what he thought his solution was. This, to help the discussion continue for anyone who was interested, not “arguing” with you.
It seems you know a lot about this and are a bit off-put by everyone not acknowledging your expertise.
These are the modems he’s using: http://www.newegg.com/Product/Product.aspx?gclid=CPCG67SrnbsCFdiUfgodlyQAlQ&Item=N82E16833114042&nm_mc=KNC-GoogleAdwords&cm_mmc=KNC-GoogleAdwords-_-pla-_-Network+Transceivers-_-N82E16833114042&ef_id=UpuCeQAABOiF-xB3:20131207050537:s
Very impressive use of a lot of cheap(ish) COTS parts.
This is something I wanted to do back in 1999. With the off the shelf tech back then, it was much harder. :-)
I’ve been watching Doug’s “channel “for a long time now, since running into it on HAD originally. Interesting projects from an interesting guy, and I’ve learned a lot in the process.
Keep up the good work, Doug.
Same here!! I loved his boat building (and his attempt at casting) videos.
The casting attempts yielded a few pairs of pretty sweet propeller blades, I was actually surprised at how good the casting was given the equipment they used…
I’m wondering if filling a small ROV with 3M Novec 1230 could counter the water pressure?
https://www.youtube.com/watch?v=qb0Px5YWspc
Seems like the big problem with that would be knocking the dust loose inside electronics
I’d imagine the dust would lift away wouldn’t it.Float away if it was flooded . Irrelevant here as if used it would be part of the original ROV construction anyway. Thanks for posting this though .Didn’t know of it . Bet it costs a fortune.
Good going Doug Amazed at his work pace.
Mineral oil is fairly standard for this purpose and is not considered toxic if there were a rupture or leak.
Silicone Oils are also excellent for this application, although Mineral oil has better thermal properties.
Silicone oils also don’t attack soft plastic parts like o-rings which is a problem with mineral oil.
fluorinert?
“custom-lathed” ???
Milling machines produce “milled parts”, but lathes produce “turned parts”. Unless you’re describing a hole made on a lathe in which case it’s “bored”. “Custom-lathed” would describe a support for plaster. At least that’s how it is in English.
Yep, your right. I have posted the same thing in earlier posts.
What I meant by “custom-lathed” was that he used a lathe to fabricate custom parts. I think if I took a survey of 1,000 people who read this comment, well over 99% of them would have understood this, making it effective communication. Doug both bored and turned parts on the ROV.
You are technically correct (the best kind of correct) and I should be more wary of any coincidentally-specific term I use to describe a generic thing, but in this case I’m not worried.
Jesus is he saying he’s wrong or is he saying hes right . What a load of tripe . Admit you are wrong and just take it like a man not a pansy.
B.S. That’s like saying ‘I custom-carred to the shop’ instead of ‘I drove’. No need to cite made-up surveys for which you provide made-up outcomes, just use the proper english words.
It would be like saying “He transported it in a boat” and someone complaining “The word is ‘shipped’, when something is carried as cargo in a boat the word you should use is ‘shipped’. No one understood what you meant!” Uh, okay. Sure. So much hate.
Hate over what, the purity of the English language?
“The problem with defending the purity of the English language is that English is about as pure as a cribhouse whore. We don’t just borrow words; on occasion, English has pursued other languages down alleyways to beat them unconscious and riffle their pockets for new vocabulary.” – James Nicoll
I used a term casually instead of the precise technical machining term, relax. The sky has not fallen upon thee. Go have a beer.
I think I just found a siggy. Thank you so much for your hilarious contribution.
Except “lathed” has a meaning, also in the construction trades. To cover a wall or ceiling with laths. At first I thought you were struggling for a way to describe the windings of carbon filaments to make tubes. Anyway, hell of a project. I want to hear more about the motors running in sea water. From my own experience at sea I will guess there will be a LOT of failures before this works reliably. Trying to get good video from a single drop camera that sits on the sea floor is an exercise in all the things that can go wrong – way more than you would think are possible.
I’d think it’d be closer to 2500-2750 feet after subtracting the path the umbilical takes going from the control system and over the edge of the boat, the fact that it isn’t going to directly below the bot the whole time, and drag on the umbilical from ocean currents pulling on it.
See the part near the end where he talks about the “dive wing” and sketches the path for the tether with and without. The dive wing forces the ROV to dive rather than just lazily drift. Of course it’s a sketch to explain the concept, not precise, but, it is something he has considered and addressed.
I wonder what it would cost to get a couple thousand feet of the fiber cable they use for trans-oceanic cables. It is already rated for several thousand feet of pressure, has in-built power conductors (to power the in-line repeaters), and could carry some pretty impressive amounts of data
Neutrally buoyant fiber is what is typically used on ROVs like those made by SeaBotixs. It’s pretty expensive stuff though, especially depth rated as deep as this is going. The cables on the ocean floor don’t carry the neutrally buoyant requirement and are likely a little easier to manufacture.
Combining it with a side-scan sonar is a really good idea.
This article has numerous grammar issues that impacts its readability.
I watched ALL of his ROV videos last night, they are awesome!
@Christopher Ahrens – He is using standard CAT5 cable, “Because it is CHEAP!” For buoyancy, he is combining it with synthetic (nylon?) rope. (CAT5 might be CAT6, don’t recall.)
Also, the dive wing is fully built. The tow cable actually attaches to the dive wing, it uses a spring so when the ROV isn’t being towed, it retracts to a horizontal position for free sailing.
@voxnulla – He has 4 cameras, a bank of 4 bright LED spotlights, and TWO sonars – one side scan and one ‘spotlight’ sonar!
@vindolin – He’s putting a lot of effort into achieving neutral buoyancy, and apparently needs the air pockets. The ROV is divided into sections which alternate between flooded and dry to provide weight/buoyancy distribution. The number of batteries will be set according to ballast needs.
@Jeff – He is using VDSL modems. He has already tested them with a 1000 foot spool of CAT5 cable (only uses 2 strands), running the signal back and forth 4 times to give 4000 feet (over-testing for a design length of 3000 feet). He ran 4 IP webcams (1 at HD and 3 set to VGA) over it, and still has bandwidth left over for C&C of the thrusters and feedback from IMU and sensors.
Love the kid with the Bowie knife. And the bow. And the shuriken.