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34

What You Will Need

r Plastic coat hanger

r 6- or 12-volt DC motor (from www.sciplus.com) 

r Model boat propeller (from a hobby shop, or 

visit www.towerhobbies.com and search on 

“boat propeller”)

r Epoxy glue

r Two pieces of #28 AWG stranded wire 

(telephone wire), each about fi ve feet long

r Electrical tape

r 2 popsicle sticks

r Two fi lm canisters with lids (If you cannot fi nd 

fi lm canisters, use 2.5” to 3” screw-top plastic containers available at any craft store)

r Twelve nails, about three inches long or 1/4-

inch diameter bolts to use as weights

r One or two 6-volt batteries (two if you are 

using a 12-volt motor)

r Container of water at least 18 inches deep 

(bathtub, large laundry tub, etc)

r Hot glue gun

r Wire cutters or wire stripper or a sharp knife

r Optional: Hand drill and drill bit of same 

diameter as the motor shaft

Make a simple version 

of an underwater 

remotely operated vehicle

Some underwater robots are controlled by 

built-in computers, and can operate without 

any connection to the surface. These are called 

“Autonomous Underwater Vehicles” (AUVs). 

Many underwater robots are attached to a cable 

that allows a human operator to control the 

robot’s movements from a ship on the ocean 

surface. These robots are called “Remotely 

Operated Vehicles” (ROVs).

What can swim deep inside the 

wreck of the Titanic?

What can sit on the edge of 

an erupting underwater volcano?

What can dive thousands of feet

 below the ocean surface?

What can collect animals no one 

has seen before from 

the deep ocean?

Build an Underwater Robot Build an Underwater Robot

Underwater robots can!

Courtesy OAR/National Undersea Research Program (NURP)

Courtesy OAR/National Undersea Research Program (NURP)

What You Will Do
National Oceanic and Atmospheric Administration (NOAA) 35

SCIENCE | Service | Stewardship EXPLORE THE EARTH

Warnings

1. Do not connect a wire directly between the two 

terminals of a battery. The wire will rapidly 

become very hot and may start a fi re or cause 

serious burns!

2. Do not do this activity in saltwater because 

everything will short out and your motor will 

be ruined.

3. If you use a knife to remove insulation from 

the wires, be careful! Put the wire onto a 

cutting board and roll the knife over the wire 

to cut the insulation, but not the wire. Keep 

your fi ngers clear of the blade!

How to Do It

1. Press the propeller onto the shaft of the motor. 

If the propeller is loose on the shaft, place 

a small drop of epoxy glue on the end of the 

shaft before installing the propeller. If the 

shaft is too large for the hole in the propeller, enlarge the hole slightly with a hand drill 

fi tted with a small drill bit. (You may need 

help from an adult for this.)

2. Hold the coat hanger so that the hook is 

pointed down. Tape the motor onto the 

inside of the hook so that the propeller is 

facing up. 

3. Tape the two fi lm canisters (or screw-top 

plastic containers) with lids on, to the upper 

part of the coat hanger. 

8. Tape the other end of each wire to a popsicle 

stick or chopstick so that the bare wire end is 

hanging over the end of the stick. 

9. If you are using a 12-volt motor, connect two 

6-volt batteries in series: Strip about one 

inch of insulation off of both ends of a piece 

of #28 AWG wire about 12 inches long. Twist 

one end of the wire around the negative 

terminal of one battery, and twist the other 

end of the wire around the positive terminal 

of the other battery. 

4. Tape enough weights to the lower parts of the 

coat hanger (near the hook) so that the coat 

hanger fl oats just below the surface of the 

water. 

5. Strip about one inch of insulation off of both 

ends of each wire.

6. Twist one end of each wire onto a terminal of 

the motor. If necessary, you can keep the 

wires in place with a dab of hot glue.

7. Twist the wires together to make a single 

cable.

fi lm canisters

or screw-top 

plastic containers

motor with propeller - use 

tape to attach to hanger

wires attached to popsicle 

sticks with tape

tape weights here
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Discover Your World With NOAA

36

10. Test Dive Your ROV: Touch the bare end of one 

wire to one battery terminal, and the bare 

end of the other wire to the other battery 

terminal. If the propeller spins but does not 

sink, try reversing the wires on the battery 

terminals. If your ROV still doesn’t sink, you 

may need to add some more weight.

Ocean explorers use ROVs for many purposes, 

including monitoring underwater habitats, 

observing fi shes and other organisms, exploring 

deepsea environments, investigating shipwrecks, 

and studying areas too dangerous for humans 

such as active underwater volcanoes. Underwater robots are essential tools of modern ocean 

explorers. 

ROVs may be large or quite small, depending 

upon the jobs they are expected to do, but they 

all have some systems in common:

• Framework on which other components are 

mounted;

Ocean explorers use ROVs for many purposes, 

Want to Do More?

1. Add two more motors to your ROV to make it 

move horizontally. You should be able to 

make your ROV spin or move in a straight 

line, depending upon how you connect the 

motors and the battery.

2. For more underwater robots you can build, 

check out these books by Harry Bohm:

 Bohm, H. 1997. Build your own underwater robot and other wet projects. Westcoast Words. 

148 pages.

 Bohm, H. and V. Jensen. 1998. Build Your Own 

Programmable Lego Submersible: Project: Sea 

Angel AUV (Autonomous Underwater Vehicle). 

Westcoast Words. 39 pages.

• Flotation so that the ROV is neutrally buoyant 

(or nearly neutral; this means it doesn’t rise 

or sink when in the water);

• Ballast to keep the robot from rolling over;

• Power to operate motors, video cameras, and 

other equipment;

• Propulsion to move the robot up and down, 

side to side, and backward and forward;

• Control to cause the robot to perform certain 

tasks; and

• Navigation to keep track of the robot.

Some of these systems may not actually be on 

the ROV itself, but instead may be on a ship and 

connected to the ROV with a cable. Most ROVs 

carry video equipment, and many have manipulator arms that can collect samples, handle 

tools, etc.

For more information about underwater robots 

and ocean exploration, visit oceanexplorer.

noaa.gov/technology/subs/subs.html. 

Scroll down the page for links to all kinds of 

submersibles!

A Little More about Underwater Robots

Courtesy Mountains in the Sea scientifi c party: NOAA, URI/IAO and IFE

Adapted from an activity by Harry Bohm and the Marine 

Advanced Technology Education Center (MATE). 

www.marinetech.org