Need WTC Ideas!

[Toffe]

Hello.

I'm currently trying to build a ROV for my own amusement and experience. What I've gone with is an Arduino Mega as a brain since i already own this. And 1100GPH Bilge pump (6x) for thrusting. So It'll much be like the Seafox design. But i want a WTC were i can contain the brain, camera e.t.c so mostly i need somethin with plexi glass on the end so i can see trough.

The big "BUT" is the limitation of supplies, Norway might be rich but if you live a little off the "big cities" you dont have the choice of materials as you do in e.g. Oslo.

What are the different methods of waterproofing something down to 50meters? Simpler, cheaper the better! I would love to use PVC pipes but i cant find anyone who sells PVC with that thickness i want (11mm).. or PVC for that matter..

Minimum size would be 20x10x15cm cubed. Could i create something by using plexiglass? I got 6mm plexiglass available.

[Kjetil]

I live in Stavanger and I did find PVC pipe at a plumbing wholeseller called Ahlsell. It cost a small fortune comparred to the prices in US and I had to buy pipe in full lenght (5 m). Maybe you can get the local plumber to order pipe and parts from Ahlsell. http://www.koi.no do have some pvc pipe parts for a resonable price.

[fluxno]

is there a special reason why you want that thick pipe, 50meter depth does not demand so much.
on the openrov they use 3mm wall acrylic pipe(OD 100mm ID 94mm).
Have you talked to your local plumber? the pipes used in water distrubution have pressure ratings of 6-10Bar and are often pvc or something like that.
or check with ahlsell, heidenreich(those selling to our local plumbers in norway) http://www.heidenreich.no/no/produkter/va/

edit: wrote 50bar instead of 50meter

[Toffe]

Ahlsell is my company's wholesaler so i might hear from them. Will check it out. But what do i need to make my WTC? What did you guys do from "norwegian" supplies? I mean, i need to be able to open it easily and have a tether cable? 50bar? What do i really need?

Going to have a camera, 2x 4A batteries, external light (outside of the wtc in a smaller WTC with a cable between) and the "brain" arduino.

Please post pictures and details on how "you" did it. Need some inspiration, "up-to" for 50 meters depth! (prolly only max 20-30 meters but just for safety sake, got 305 meter tether cable. going to cut out 50m)

[Kjetil]

I made my WTC by using 110mm pipe with a cap on one end and a union on the other.

Link to Ahlsell product catalog: http://np.netpublicator.com/netpublication/n68201057
End cap page: 190
Union page: 188
Pipe page 194

I have bought a plastic dome from http://www.ukplasticfabrication.co.uk/A ... domes.html

In my WTC I have the following equipment:
Arduino Mega with homemade overlay card
Relay and fuse board
20 ea 1,2V D-cell Ni-MH battery
10 ea 1,2v C-cell Ni-MH battery
camera and two servos for control of camera

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[Toffe]

Nice, how deep does it go "watertight"? Tested any limitations?

I'm probably gonna do the same as you, but using mosfet, diode and resistor for each thruster instead of relays. Using mosfet's i found in my hobbyroom which is rated for up to 60volt and 30A. Should be enough for each thruster. Have enough to make around 20 "homebuildt relays".

I love how you have done it, neat and clean. Dont think mine is gonna be so "neat". Not V1 atleast

Lets see if i get you right, you have glued the O-ring part of the union on the 110mm pipe, then got a dome fitting the unio o-ring part and threaded the "nut" over it. About depth you got any "info" again?

And the back end is that also possible to open? How did you e.g. do the cable exits and light?


(Seems like i'll do a 160mm tube)

[Kjetil]

I have only tested it to 13 meter by just lower it 13 meter in water. I have not found a place near me where there is deeper water. That was before I drilled holes for the connectors. I have not tested it after. But I have tested the connectors to 3 bar without any leak Was not able to test to highet pressure since the water pressure is only 3 bar where I live.


Back end is not possible to open. My plan is to push the batteries in and then connect all the cables through the connectors. If I need to remove the battery pack then I have to remove all the cables.

Picture of the union with all parts:

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The relays shown on picture is not for thruster and/or light control, they are to turn ROV on/off and to change where the power from the different battery is going to.
Board on the ballast housing have mosfet for controlling thrusters(connected to a digital port on the Arduino Mega, so these are only on off) and light control with use of PWM

Below is a shematic of electrical parts of the ROV.

Visio-Elektrisk Ver 5 BUK555 08.11.pdf

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Picture of relay board for the ballast, thruster and light control.

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[Toffe]

Just a quick question before i leave (I'll read rest of the post tomorrow just saw the images now) but do i really need that much cooling for the mosfets at 3.5-4 amp / 12v ?

[Kjetil]

About the cooling. I do not know. I have tested them when running the bilge pumps with out any load. The mosfets did not get hot. The only reason why I have used these is since this is the only ones I had available.

[Toffe]

http://www.skylighter.com/6-inch-fiberg ... r-tube.htm

What about theese, will it be stronger than PVC?

And is it possible to fill the hull with pressure before diving to equalize the pressure a little?

10 bar inside = 0 bar at 10 meter down, then at 40 its only 30 bar pressuring.. Adding 20 bar inside you'll get 20 bar at 40 meters?