Introduction: Underwater Remote Control Drone
I decided to build this ROV for the purpose of exploration and admiration of the underwater world because there are not many cost-efficient underwater drones out there. Although it takes a lot of time, research, and autodidacticism, it is a fun project that allows you to explore bodies of water near you.
Step 1: Building the Frame
The first step in building an Underwater ROV is to design the frame. I chose to make a 12x12x10 inch PVC pipe frame with a small window at the front for the camera. For my design, I needed a PVC pipe cutter, PVC pipe glue, hot glue, 10 1/2" schedule 40 PVC Ts, 10 1/2" schedule 40 PVC elbows, and about 10 feet of 1/2" schedule 40 PVC pipe. Cut the PVC pipe into pieces that fit your design, and sand the individual pipes then glue them into the joint pieces to create the frame and finally hot-gluing the edges of each joint piece to keep it together. Be sure to drill multiple holes into the frame to allow water to fill it, causing it to sink.
Step 2: Attaching the Thrusters
For the next step, you will need six underwater bilge pumps that will serve to propel the ROV forward, up and down. You should also have two plastic grids that are able to be strapped to the top and bottom of the ROV and will hold the thrusters, termination cans, weights, and ballasts. Be sure to label each thruster(this will come in handy when wiring thrusters to the positive termination can and the remote control).
Step 3: Wiring Thrusters to Termination Cans
Next, you will need two small electrical boxes with at least seven connection terminals, #18 gauge hookup wire, and 50 feet of 7 cabled #16 gauge hookup wire(I found that sprinkler wire works best). First, drill small holes into the electrical boxes to allow the wires to go into. For the negative termination can(pictured on the right side), thread the bilge pumps' negative wires in along with the #18 gauge hookup wire and strip them far enough down so that you are able to wrap all of the bilge pumps' negative wires around the #18 gauge hookup wire. Use a soldering iron to ensure that the wires stay wrapped around one another.
In the positive termination can(pictured on the left side), thread the bilge pumps' positive wires in and strip them down enough so that they are able to be screwed into the connection terminals, but be sure to remember which thruster's wire is screwed into which adaptor(this is where labeling the thrusters comes in handy). Next, do the same with the sprinkler wire, noting which of thrusters corresponds with each of the colored #16 gauge hookup wire. The seventh cable in the sprinkler wire should be screwed into the same terminal as the #18 gauge hookup wire that is also in the negative termination can; this is called the ground wire and returns power to the negative termination can.
Step 4: Attaching Weights and Floats
In order to establish a 'top' and 'bottom' while underwater the drone will need something to keep the top positively buoyant and the bottom negatively buoyant so that it does not flip over in the water. In order to keep the top positively buoyant, I used two 4" diameter PVC pipes in which I attached endcaps the same way I did when assembling the frame, with PVC pipe glue and hot glue around the edges to keep it airtight and buoyant.
For weights, I used three, one foot long 1/2" PVC pipes filled with rocks. I also drilled multiple holes into the pipes to allow water to get in. You do not need to glue the end caps onto the weights because there is no reason to keep them airtight and you may have to adjust the amount of weight in each pipe. I used zip ties when attaching everything.
Note: You will still have to buoyancy test the ROV to make sure it does not sink straight down or float so much that the thruster is not able to push it down.
Step 5: Creating the Remote Control
To assemble the remote control, you will need a 6x4x2 inch project box, six pushbuttons, a connection terminal with at least 7 connecting terminals, #18 gauge hookup wire, and a 12-volt fuse. First, drill a hole in the front of the remote that is able to fit the sprinkler wire and on the side that is able to fit two #18 gauge hookup wires. Hot glue the terminal strip and fuse as seen in the picture. Drill six holes into the top of the project box that are able to fit each pushbutton: up, down, left1, left2, right1, and right2.
First, screw the negative wire into the first terminal and #18 hookup wire in the corresponding terminal and feed it through the hole that you drilled on the side of the remote, this will be the negative wire for the battery. Next, strip the remaining sprinkler wires to be wrapped around one screw of the pushbuttons. On the other screw, wrap #18 hookup wire that will lead down into the other six connecting terminals. For the corresponding terminals, screw-in #18 hookup wire that connects to all six terminals and finally wraps around the fuse to prevent overcurrent that would melt the wires or create a spark. Wrap another #18 gauge hookup wire to the other side of the fuse and thread it out the side hole, this will be the positive wire for the battery.
Step 6: Testing the Thrusters
Before you can waterproof everything, you will need to test that the thrusters are working properly. Connect the positive wire from the remote control to the positive battery clip and the negative wire to the negative battery clip. Clip the wires onto the battery and test that all of the thrusters work and are connected to the correct button.
Step 7: Waterproofing
To waterproof the onboard termination cans, you will first need to hot glue around the holes where the wires enter the box, be sure to hot glue the inside and outside. Next, you will need three boxes of toilet seal wax which will create an airtight seal to prevent water from making contact with the exposed wires. Melt the wax using a double boiler method, pour the wax to the top of the termination cans, and leave to cure for at least 24 hours. Be sure to put the screws in the screw holes before you pour the wax in to prevent any wax from getting in the screw holes of the termination cans. Once the wax has fully dried, screw on the lid and hot glue the edges.
Note: Once you waterproof everything it will be extremely difficult to make any changes so be sure that everything is working properly.
Step 8: Camera Setup
The easiest and fastest way to attach a camera to your ROV is to buy a fishing camera and attaching it to the frame as seen in the picture. This camera comes with its own monitor and led lights. You can also research into making a waterproof housing for a bit cheaper, non-waterproof, camera, and connecting it to a monitor such as an old portable tv player but I found that has many issues.
Step 9: Tether Setup
Finally, you will need to organize both wires(sprinkler and camera) as well as attach a rope to the ROV in which you can pull the ROV ashore. To ensure that the tether does not sink to the bottom and get caught on anything, zip tie little pieces of foam noodles to all three chords, this will also zip tie the wires and rope together. To effect the buoyancy of the ROV as little as possible, zip tie smaller pieces of foam noodle to the part of the tether that is closest to the drone. Once all three chords are organized, wrap the tether around a chord storage reel.
Step 10: Please Take Note...
Due to the increasing problems facing the earth's oceans, I encourage you to not only do more research in building an underwater ROV but also how you can help protect and preserve the natural beauty of the underwater world.
Here are some helpful links:
Chasing Coral - Netflix Documentary
Mission Blue - Netflix Documentary
A Plastic Ocean - Netflix Documentary