Waterproof Electric Engine!!!

[soudan]

Ok here is the deal, I wanna make a mini ROV just for fun, but i ran through a few problems while thinking of how to make one.

here are the issues:

1. How will the shaft go from the motor to the propeller without water getting to the engine?

2. how do you water proof the weirs going from the ROV to the control box? (do you buy special cables for that??

also if anyone has any planes drawn that they don't mined sharing i'll be very grateful.

thank you all...

 

[Warthaug]

There are plans for what you want on the net - google for "DIY ROV". In regards to your specific questions:

There are two general ways in which motors and propellers are connected. One is to use a gland, which is basically a rod sealed with o-rings. The second is magnetic coupling - where there is no direct connection between the motor and prop, but rather the motor is completely sealed and the power gets transfered using magnets.

As for wires, usually you try to design so you don't have exterior wires. If you must have them glands, like those use for the prop, also exist for wiring. Keep in mind you'll want heavy-duity wire with thick insulation, as the slightest nick will lead to a short.

Bryan

 

[Gary D.]

Trolling motors. Cheap and work great.

Gary D.

 

[RICHinNC]

does it matter as long as it is DC power?

 

[nwbrewer]

This is something I've been thinking about too, Gary D. do you have any brand recommendations on a trolling motor to look for? Are any of them Magnetically coupled? I thought most of them used a bushing that wouldn't work at any significant depth? Thanks.

jake

 

[FatRob]

does it matter as long as it is DC power?

Oh yes it matters! Especially if you want the thing to work... Salt water likes to short out DC just as much as AC, and fresh water (not distilled) is not a lot better, since it contains quite enough dissolved salts to short the circuit.

Commercial solutions exist, generally you will want a double o-ring seal, lubricated, for all shafts, and I would use waterproof connectors. www.impulse-ent.com or subconn or seaconn should give you some ideas. Those connectors are NOT cheap though so be warned. For shallow water <100m I would use a cable gland like Halcyon use on their light systems.

You may be able to find a fully potted motor that runs underwater, and I did come up with a great way to do this, unfortunately some dude in Southampton already publised it!
(Abu Sarkh, S.M. et Al. - IEE Proc. Electr. Power Appl. Vol 151 No 5, Sept 2004, pp513-519)

Also take a look around for radio contol model submarines

Cheers
Pics please when you get it going...

 

[astrohog]

make the frame from pvc 1 inch or what ever and and screw on bilage pump from boat and u can put the wires through the frame and just a large hose with all your wires as an umbillical

 

[soudan]

Oh yes it matters! Especially if you want the thing to work... Salt water likes to short out DC just as much as AC, and fresh water (not distilled) is not a lot better, since it contains quite enough dissolved salts to short the circuit.

Ok, but the goal is not to have water touch the electronics at all so i still don't get why would it matter if it was AC or DC!!

 

[soudan]

There are plans for what you want on the net - google for "DIY ROV". In regards to your specific questions:

There are two general ways in which motors and propellers are connected. One is to use a gland, which is basically a rod sealed with o-rings. The second is magnetic coupling - where there is no direct connection between the motor and prop, but rather the motor is completely sealed and the power gets transferred using magnets.

As for wires, usually you try to design so you don't have exterior wires. If you must have them glands, like those use for the prop, also exist for wiring. Keep in mind you'll want heavy-duty wire with thick insulation, as the slightest nick will lead to a short.

Bryan

They sound logical, but i am trying to build it with what i have (i am in Egypt now), and i don't think i could get my hands on or build any of them!! any Ideas

 

[Danman589019]

I've seen people using bilge pumps as jet drives to push it around instead of using motors and props.