This is a great, easy, weekend project! This project is also a first prize winner in the 2012 Instructables Robot Contest!

So, this little submersible uses 3 DC motors and a nine volt battery. It controls the three motors with three buttons. It's frame is built from lego-type pieces. It is very simple and great for kids to learn. Although you will need some sort of supervision because the project involves a soldering iron.

Step 1: Parts and Tools!

There aren't too many things involved and if you take things apart a lot like me, you should have most of these things. I will also attach Radioshack links next to the parts that they may carry.

(3) Push buttons or switches  http://www.radioshack.com/product/index.jsp?productId=2062495
(3) DC Motors (at least two have to be the same)  http://www.radioshack.com/product/index.jsp?productId=2102822
(?) I built my frame out of pieces from a physics workshop kit, but as long as it holds the motors and isn't too heavy, anything should work 
(1)  9V battery connector, or if your using different voltages, a different battery holder. http://www.radioshack.com/product/index.jsp?productId=2062218
(4) Empty Film Canisters. These will hold the air that will float the ROV (Remote Operated Vehicle) back to surface.
(3) Propellers. These go on the motors to propel the ROV. I found one off an old model plane and two laying around.
(1) Some solder. Most anything should work. http://www.radioshack.com/product/index.jsp?productId=4314832&filterName=Type&filterValue=Solder
(1) Some hot glue. 

Soldering Iron. anything should do. Just needed to solder a few pieces together. Make sure you have permission to use this.
Hot Glue Gun. I used this to glue to film canisters and the motors onto the frame. 
Helping Hands. These work REALLY good. I used kind of a make do one, but these help when your trying to solder something. 
A Bath Tub. Something to test it in.
(Optional) Wire Strippers

Step 2: Put Together the Frame

One you gave gathered all of your materials, you are ready to begin constructing the frame of the ROV. It must have an area on the top to glue four film canisters. It also needs an area in the middle on the bottom for the motor that propels downward and two areas on the bottom for the motors that propel forward. Use my frame design to make yours.

Step 3: Assembling the Motors

Before you attach the motors to the frame, add very long leads to the positive sides of the motors. The negative sides only have to be about 4 inches. It also helps if you use different colored wires to the positive and negative side. Once you have the leads on, use a hot glue gun to glue your propellers onto all three motors.

Now, use a battery and touch one lead of a motor to the positive side and the other to the negative. Note which leads went to which sides of the battery. When the propeller turns on make sure it is blowing air. If it is not, switch the leads on the battery. When it blows air designate the wire going to the negative side of the battery as "ground" and the positive as "positive". Make sure you do not get these mixed up.

Now, glue the 3 motors you collected onto the frame. The two that propel forward have to be the same and the one that propels down can be any size. Glue all three into the areas designated for them. Make sure the downward propelling motor is in the middle of the bottom of the frame and that the other two are on the back.

Step 4: Wiring

You should have all of the motors securely fastened onto the frame. Now, take all of the leads you designated as "ground" and solder them all together. There should be three. Next solder a very long wire (depending on the depth you want it to go) to the joint you just soldered. This is the ground wire.
Next grab those three buttons you got. If you have one of those helping hands, clip the button to it. There should be three little leads of metal on the bottom of the button. When the button is pressed down, it connects the two right leads and when it's up, it connects the left two. So we want to connect the motor lead to the middle and the battery to the right so when it is pressed down, it connects the battery to the motor and it spins. So as I said, solder the positive motor leads to the middle of each button.
Once a button is soldered to each positive motor lead, we can start with the battery. Grab your 9V battery clip. It should have one red and one black wire coming out of it. The red is the positive and the black is the negative. Strip the ends of each of these wires. On the positive wire, solder on three 5 inch wires. So now there should be 3 positive wires and one negative one. Grab that one "ground" wire you connected to all of the motor negatives and solder that to the negative wire coming out of the battery clip. Now get all of the buttons you just soldered. The positive motor lead should be connected to the middle lead. Solder one of the positive wires coming from the battery clip to the right lead of each button.
So now you should have everything connected and no open wires. If you do reread this step. You can test that you did everything right by putting in the battery and pressing the buttons. Make sure that each motor runs. Almost done!

Step 5: Finishing Up

Now find where you want to put your film canisters and hot glue them to the frame. Make sure they are centered so it is not tipsy.
Once you have them on, your ready to test it out! Put it in a bath tub or something to test it! If it is back heavy, you may need to add quarters into the from film canisters. 
I hope you really enjoyed reading or making this project. I learned a lot myself and had fun. Please Vote For This In The Robot Challenge!!! Thanks!
Great job! I would love to see a video of it in action.
Thanks! I actually meant to post one. Tomorrow I will post one! Please vote for this is the Robot Challenge!
You have my vote!
Thank you so much!!
Awesome! Kudos galore!
Thanks! I would be so happy if you voted for this in the Robot Challenge!
Nice work!
Thank You! Please vote for this in the Robot Challenge!
<p>is there a replacement material for the body?<br></p>
I made it,but it didn't work.Pls tell me why l,I will try to change batt after this
<p>found the ingredients,i think dptd toogle switch is way better</p>
Awesome Instructable! After reading this I had to build my own. I recommend using DPDT toggle switches for the motors so you can reverse the polarity and change direction.
<p>what did you make it from,i already attached everything.The only problem is don't have enough lego parts.Any idea what shall i use?</p>
Thanks!! Yours looks awesome!
<p>How do you control the speed???theres no sc here</p>
<p>Amazing job. Stark simplicity. Very Impressive! </p><p>Sealing the motors would be a great next step. Would love to see how you choose to do that?</p>
I'm going to make this, however, are the motors water proof?
Very nice work! <br> <br>I'm curious how long the motors lasted. Did you try sealing them? <br> <br> <br> <br>Jim <br>Victoria, BC <br>
Thanks! I did not try to seal them. To this day one of rear motors has stopped working. If I make another one I will probably try to seal them!
my god
i've done this with my students before and the author has done an excellent job. the thrusters last quite awhile but do eventually corrode.... lots of time to experiment though!
If you were worried about the motors corroding, you could seal them in like they do on the SeaPerch ROVs, they have a manual here: <a href="http://www.seaperch.org/teacher_tools" rel="nofollow">http://www.seaperch.org/teacher_tools</a>
Thank you!
You need to make the video 'public' so we can see it.
Sorry about that! Thanks for telling me, I would have never realized!
Wouldn't the motors fry?
I don't think so. The voltage used is fairly low so I would think that there would only be a minimal loss of electricity due to the semi conductivity of the water. I would think that there would eventually be some rusting or oxidization on the motor casing or brushes which might affect the motors performance after a while.
Yea, there would be some oxidization if used in chlorine or anything, if in fresh water its fine, and the motors would be fine, you could actually overvoltage them due to the cooling effect of the water

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