elephunk

Hi guys, I'm looking for some help if someone fancies throwing their 2 cents in.....

My son and I are starting to plan to build an ROV for exploring lakes and canals and such. I have a good idea how to accomplish it, but am just looking for help choosing some key components.

So the ROV is going to have a frame built from 21.5mm pvc pipe in the shape of a box, then I will attach the components inside.
My initial idea for the thrusters is to have one motor inside 110mm pvc pipe mounted centrally at the front, split into 2x 50mm thrusters on the back, one left side one right to balance thrust. This motor will be run in reverse to give reverse thrust.

Wihile I was researching what other people have used before for thrusters, one thing that has struck me is the documentation for this kind of thing is quite old, well what I've found anyway. The most common choice has been modified bilge pumps. While I don't have a problem with this, they are kinda bulky and I was wondering if anyone here had a better recommendation. I don't mind the bilge pump idea, but to me they just seem a bit bulky and I just have a feeling there is a better option available that I am missing. I have seen brushless motors can be run in water, but not having any knowledge on this I need to ask for help of someone with some knowledge.

The next one is waterproof servo's. I am looking at adding rudders to the thrusters, so I've had a quick look on ebay and can see there are servos claiming to be waterproof, but havent found one to give an IP rating. So could I use one for this application??

In reality this sub is going now lower than 20m max.

Last one is bi-directional propeller. Havent the foggiest where to begin so any help with this would be greatly appreciated.

Many thanks in advance
Iain

Gato.Submarine

I would not run my servos in the wet. Even servos that claim they are waterproof. These are hobby grade items and you are correct not rated. Almost all submariners build a Water Tight Container or Cylinder (WTC) for their subs and use a seal or gland to have a rod exit the dry area and control rudder and dive planes. This keeps the radio reciever, Electronic Speed Controller (ESC), motors, servos, and other electronics dry.
A prop is designed to run forward or reverse. Is this what you mean bi bi-directional? If so and ESC is what you need. Any decent hobby store or web site will have them. The ESC you select will depend on what motor you run (brushed or brushless), the size of motor, and the size of prop you run. A good balanced system and your motor will not get hot. You have a lot to go through if you have not done submersible devices before.
Go to sites like:
www.subcommittee.com - they have a very nice beginners tutorial

www.theassociationofmodelsubmariners.com (AMS) also a nice beginners area

forum.sub-driver.com this site does not have a beginners site, but many how-to and submarine builds

www.rcgroups.com/submarines-60/ some good discussions and ideas

www.subpirates.com/forum.php this site has some good information too. Some dated, but the basics are the same and are timeless.

I am not sure where you reside, but there may be someone who lives close to you that can show you the workings. Also, subcommittee and AMS post local shows that you can go to.
Peace,
tom

Gato.Submarine

I posted and it was put on hold. is it going to be released?
I offered links to areas that will help this individual work on their ROV. When I posted it said it would need to be reviewed and approved. May I ask why?

elephunk

Thanks for trying to help Gato.Submarine