ROV (DIY)

[rgecy]

Well since I was showing off the magnetometer, I came across some of the picts of the ROV my Son and I built.? It has proven useful to about 60ft and has a great image if water visibility is good.? Thats the only problem here in SC, we have terrible vis.? Less then 5 feet some times.? The vis only gets good when you get offshore 10-15 miles.? None the less, it has proven to be a fun project!

It's a modified version of the Sea Fox ROV in the book by Harry Bohm, "Build your own underwater robot."? Here are some great ROV links if anyone is interested.? This design can be built for less than $300.

http://groups.yahoo.com/group/robotrov/?yguid=195345130? ? ROV Forum
http://home.comcast.net/~homebuiltrovs/? ? ?Steve Thones ROV Page
http://members.rott.chello.nl/rengelsman/? ? ? Link to ROV Links? (See Homebuilt ROVs at bottom)
http://jackson.parcabul.com/rov/index.html? ? ?Doug Jackson's ROV Page

You can see the original version I built using the bilge pumps and the modified version wher I converted the bilge pumps to thrusters.Robert in SC

 

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[rgecy]

Cornelius,

Go with the 1100GPH model.? The more the better.? The first thing you will need to do is make your frame.? Its made from 1/2" PVC pipe.? You will probably need about 16 feet to be safe.? You will also need 14 - 1/2" T's and 10 - 90deg elbows.? The bottom support is made from a plastic coca cola crate.? I'll tell you what, I am going to scan the pages from the book and send it to you.? It will show you some options you have on building it.? Mine is a modified version and I will make some notes and send those as well.

There are alot of options. You need to do alot of reading at the sites I posted. Don't hesitate to ask questions. I'll be glad to help with what ever I can.

Good Luck,

Robert in SC

 

[seal]

I am having some problems, is there a general basic plan that everyone goes by then modifies themselves to suit their needs or what as I am unable to find this plan.

 

[wreckdiver1715]

Robert; I like your ROV and am currently building one down this way. I see you made modifications to the basic SeaFox design. Question; your thrusters don?t appear to be the standard bilge pumps, A; I only see two Aft thrusters, and one vertical, and B; did you modify them, ore use something else? I also see that you appear to have been able to reduce the volume of your floatation requirement, by reducing the number of thrusters.
I like!

Q

 

[lobsterman]

WOW, i can't believe the ROV at the gov auction that i mentioned to a few of you, is up to $23,000.00 already, nice unit but i never thought it would go that high, it makes me want to start building one right now .

Pat.

 

[lobsterman]

Hi cornelius, do you sell your ROV's ?, i think i remember seeing one by that name on the market before, along with a few sister models. i don't remember if i had sent you the info on the auction, i'll send you the link by PM.

Pat.

 

[rgecy]

Since we were talking ROVs, I thought I would refresh this one.

Good luck with all the ROV projects out there. They definately are fun to operate!

Robert in SC

 

[ceolacanth]

Just a little input
I have read several of the comments and discussions and thought I might toss this out there

Regards motors, I know most of you are attempting really small ROV's but dont short yourself on power, electric outboard trolling motors come watertight with thrust bearings and even a prop to boot (you can change the size and pitch if you wish to increase speed or thrust) they come in a wide variety of sizes and are all 12VDC. They are all reversible (although very few ROV Motors get exact equal performance FWD-REV). So now all you need to do is increase the depth peformance (I have tested to 25ft AS IS and only after that did I experience problems)Increasing depth is best achieved by eliminating the external pressure (or should I say pressure inbalance from either side of the seal)
One must Increase the pressure insisde the housing to match the external pressure of the water using a mediium ( I initially used a modified scuba first stage and linked all the thrusters to a small pony cylinder it works, but in a really small vechile as you use the air, you create bouyancy from the pony tank anyhow I wont go on about bouyancy as I tend to go on and on.

In short take the electric outboard either cut the shaft or remove it (or adapt it using a method similar to what Cornelius described to allow you to tilt the thrusters)
drill two small holes about 3-4 inches apart 1/4 inch dia will do then thread both holes (its soft pvc /plastic) insert a hose barb (threaded one end ) into each hole . Now fill the motor with oil (low viscosity hydraulic will do NB NON CONDUCTIVE ) Connect the two hose barbs with a clear plastic tube in a slight bend use a tiewrap it will hold just fine . Ensure that the complete motor housing has no air bubbles and the plastic hose is full of oil. (i use a small hand pump to flow the oil through the motors for cleaning and refilling this ensures there is no air trapped a bit like a brake bleeding tool)

And voila you have a motor that will easily obtain 600ft (in fact this is the same method used for full ocean depth thrusters)

I WILL SEND SOME MORE INFO ON HOUSINGS FOR LIGHTS AND CAMERAS IF ANYONE IS INTERESTED

 

[Treasure Seeker]

Thanks for the info Ceolacanth. I've researched "real" thursters and noticed that many of them are filled with oil.

I never thought about applying that same concept to my own motors...

So just by filling them with Hydraulic oil, that will give them roughly 600 feet? Just curious, how is this number determined? Is that a value associated with the physics of the oil?

Thanks -- and yes, any other info you have would be awesome!

My first ROV will be a small one to have fun with the kids with... But the one I *really* want to build is more of a hybrid ROV/AUV... Can't wait for winter to get here -- my hobby/project time.

TS

 

[ceolacanth]

T S
The depth of oil filled thrusters is "full ocean depth" which in real terms is 28000 ft the problems arise with 3 main things:
1) the absolute removal of all air from casing
2) the distortion of the outer shell material.
3) the thrusters must run continuously or the oil needs to be heated as it tends to go a little like molasses when the temp drops. (this is not detrimental to the actual thruster itself just its performance and amperage peaks on start up)

The 600ft is at what pressure most plastics / pvc start to take on distortion and the characteristics and properties of the material can alter to such an extent it can have catastrophic failure. A better material here is Delrin.

This same principle can be adopted for umbilical and electrical housings on the rov. In order for them to be pressure proof to say 1000ft the housing would need to be substantial and usually cylinder shaped with capped ends (these are awkward for building components into) being substantial means also being heavy (using aluminum or titanium cylinder walls can cut down on wall thickness but the downside is the end caps which add all the weight) to counter this weight they are usually constructed larger to add buoyancy to balance it all out (syntactic foam can also be used but is still not as efficient as solid open space buoyancy) Anyhow before I ramble off into the ROV/SUBMERSIBLE nightmare of weight vs buoyancy I will go on with the explanation:

Umbilical termination boxes and electrical (not electronic) junction boxes can now be a simple off the shelf watertight electrical box (a good make like Klockner Mueller etc which also has a clear front ) oil filled with a simple hydraulic compensator attached or the fill hose can be say 1 inch dia and mounted on top of the box (use clear soft pvc hose about 2 ft in length this hose will act like the hydraulic compensator it will allow the external pressure to act upon the oil keeping both internal and external equalized.
The hydraulic compensator is nice as it allows expansion of the oil if you are working in warmer shallow waters ( anything can be used for this the principle is a half filled syringe allowing the water pressure to push down on the plunger thus forcing oil into box and equalizing pressures, if the temperature increases then as the oil expands it pushes the plunger out) oh yes the position of the plunger is usually half way I have come across many different types of homemade compensators and they all appear to do the job.

So by using this method we have simplified the umbilical termination box and all electrical outlets. It also allows you to use a less expensive or even a homemade umbilical as the oil is forced up the umbilical the deeper you go (you use a standard outdoors nylon cable compression fitting to attach umbilical to box) The same goes for all other connections Thrusters, lights etc. (here I want to point out that it is always best to run higher voltage and step down on the vehicle as it keeps umbilical size down which results in cost savings and easier tether management for both yourself and the vehicle)

If you wish to keep a watertight connection from your umbilical to the vehicle and dive it to anything over 400ft then you need to spend a lot of money on the umbilical or it will simply collapse at the vehicle end . An interesting test (if you don?t have a test chamber handy) is to terminate the end of the umbilical you plan on using with epoxy 50/50 two part cold mix ( just use a larger piece of hose pipe or something for the mold ) it must go up the umbilical at least 6 inches and extend 2 inches below then once set lower the umbilical to your working depth and see the results any non custom cables will just compress to the extent of destruction .

Regarding cameras, lights and housings I will post something tomorrow in more detail if you wish, including how to make your own through hull waterproof connections as these are usually a killer when you have to purchase and using standard $ 75 echo sounders as altimeters. In the meantime here is a link to a site with pressure housing software programs ( they are costly but they have a demo you can play with)
http://www.deepsea.com/underpressure/
Another good pressure vessel site is : http://www.prevco.com/
Have a look around and get ideas on how you would make your own its really not that difficult.

Hope any of this helps or makes sense.

 

[Dinkydick]

Ceolacanth:

I have been waiting around for some more of your contstuction tips (and possible pics) but none
have come. I am sure there are a few subscribers to this net who would like to know more about
buliding an inexpensive ROV. I am one for sure.

My problem is working an ROV in high current and near zero visability. Do you have any suggestions
on how to atleast combat the high current problem?

My working depth would be limited to 100 feet.

Let me (us) know some of your secrets.

Thanks

Dinkydick

 

[ceolacanth]

Sorry for the lack of response but work calls at the present and time is limited but I will get around to it,
Question1) just how strong is the current?
Question2) is all the work you envision on the seabed ?

The visability can be overcome (within reason) but their are costs involved, the current on the other hand (dependant on actual strength) can pose a problem for smaller vechiles.(a downline weight can assist here though ) I asked if all the work was on the seabed as in really strong current areas small crawler type vechiles can often be more efficient see below link (just to give you the picture)
http://www.roboprobe.com/CATALOGS/C38-LIST_ROBOTS_AND_ROVS.HTML

Last Question : if its only 100ft why not just dive it?

 

[Treseekr]

Re: ROV (DIY) wire/voltage drops

voltage/amp drop formulas will help with any ROV applications. Also submersible wire link. http://www.powerstream.com/Wire_Size.htm http://www.houwire.com/catalog/products.asp?catid=73

 

[Dinkydick]

Cornelius:

I have a question regarding your Reply #9. When you referred to "CAP" magnets - What are these
and where can I get some? I think I know what you are referring to but I didn't know that they are
available already made up.

Please explain, Thanks

Dinkydick

 

[Dinkydick]

This is my reply to both Ceolacanth and Cornelius:

I have chosen the worst possible conditions underwhich my ROV will be utilized.

I live in a costal town which has 260 mile long river running through it. In my location the river has a
maximum depth of 110 feet and is about 1500 wide. It is tidal in this area (about 5 feet). This location has a standard current of from 4 to 5 knots either coming in or going out. Actually the water goes in opposite directions as you get deeper. Ceolacanth - I have worked in this area and it took four grown men to pull me to the surface during high current conditions as I was wearing a 85-pound belt and a
Desco dive helmet. I was doing no-D dives everyday.

Cornelius - I really don't have any particular search site in mind, just a alot of questions on designing a ROV to operate under these conditions. Oh, did I mention that the water visability on a GOOD day may be one-foot.

I have chosen this site to test the operation of my NOT-YET-BUILT ROV. If it will perform somewhat
I will be happy as I am not getting any younger and may not have enough time to build another one.
I have alot of ideas to try.

Once the ROV is built I plan on installing a manipulator. I have seen some nice ones over the years. Some can be built quite cheaply.

I am always open to suggestions. Pic of one I designed and built in the early sixties to follow.

Dinkydick

 

[Dinkydick]

Here is the PIC

Dinkydick

 

[sthone]

Hey Guys - I'm new here and I'm probably jumping in late but.... I think working in that much current your best/easiest bet would be to use trolling motors. The 100' depth would probably mean they would have to be pressure compensated though. I saw one article about filling them with oil and I think theres a few guys that attach scuba regulators to them somehow to do this but I've never really looked into it yet. If this is something you'd be interested I could find the article or put you in contact with someone who has done it.

On a side note - the magnetic coupler idea is the best way to go, no leaking seals to worrie about. I've been working on a few designs for one but haven't gotten too far on building one yet i've only done a few simple tests so far.

Cornelius do you have any pictures of your set up or Rov?

I'm sure a few of you have all ready been to my site. If not here's the link http://www.homebuiltrovs.com? you can see a few of my projects.

-Steve​

 

[ceolacanth]

Hi all,
I am currently away from home but will submit ROV info promised upon my return,
Dinkydick - I dont think you will get a small rov capable of working in that type of current (effectivly that is) even rare earth metal motors would struggle moving a ultra light ROV in those conditions and if you kept the ROV too light it would struggle to stay down with that amount of current. I would guess a small crawler type vechile would be best unfortunatly if the wreckage stands proud of the seabed to any great extent then you are limited to the reach of the camera/manipulator articulated boom.(although they can reach up about 8-10 ft even on smaller models)

Sthone: if working less than 300 ft I would stick with air compensated (Note dont make my mistake and install a regulator on each motor, just link them all up to one which is connected directly to pony tank.

Cornelius: I like the rudder idea for steerage. I have used a small drouge behing the vechile to keep its track and heading in a straight line, but also observed some others who simply allow a larger bight of the umbilical to trail behind tiewrapped off and it seemed to work just as effectivly(the drouge did work better in cross current) Tow depressors are great in allowing you to increse vessel speed when towing. I used a seperate tow depresser upwards of the vechile but often encountered problems when slowing down to inspect an area in more detail. I have since then "beefed" up my camera /lights platform and now have two small dive planes either side of the vechile which I operate using camera tilt. So long as you strengthen the mountings and do not wish to utilize a larger "rotator" motor it will still work fine you just have to slow down vessel speed to alter or adjust dive planes. Usually the camera is still pointing in the direction you need it to face but if not just shim it up until you get a happy medium.

 

[FISHEYE]

My ROV

http://68.205.197.69:81/ROV/ROV.html

 

[Narked1]

Have been reading the chain here and, having never built an ROV myself (so please forgive my ignorance), I have a question. What is the possibility of attaching a transducer from a fishfinder to the ROV to provide a "picture" of potential sites well ahead of the camera's viewing range in order to provide an advance silhouette of potential sites. Would be advantageous in low viz situations.

I think that this may work well at shallower depths, possibly 100 feet depending on type of system, due to impedance of the transducer cabling.

Just a thought. You all have piqued my interest here and I just may have to start building my on ROV to stay busy during the diving off-season here.

Mike