ST
21
OUR SEAPERCH
1. Our ROV has foam that helps it be neutrally buoyant. This makes it easier to
control since it is not sinking or floating (much).
2. It has holes in it to allow water to fill to cavities so that it won’t float. If it
stayed full of air, it would float.
3. Our ROV has motors powered by electricity that spin, forcing water to move
and pushing the ROV in the opposite direction.
4. We installed a tether cable that supplies the motors with electricity so that
the ROV doesn’t have to carry around a giant battery. Batteries are heavy
and would make the ROV sink. The tether cable also simplifies the design
since the ROV doesn’t need to receive radio signals through water.
5. Our ROV has a specially designed net inspired by the challenge video that
allows it to catch balls easily and hold them in. Balls can be caught on the
surface, held and then released because the net has a little lip to hold balls
but not such a big lip that it is hard to release the balls. The ROV also has a
net specifically designed for pushing the golf balls along the bottom of the
pool.
6. The ROV uses zip ties to attach the net to the PVC frame, create a lip in the
net, hold the floats so that they don’t slide back and forth, and securely
hold the motors to the frame.
7. The ROV has a PVC frame which provides a place to attach motors and the
net. The PVC frame is light so it does not sink excessively. PVC is also
inexpensive.
The basic DC motor mechanism
The switches are simpler. When one is pressed, or flipped,
a piece of metal is inserted so the electricity can flow from
the battery to the tether cable and into the SeaPerch.
When the switch is neutral, the metal is taken away and it
can’t flow.
APPLYING MATHEMATICS
It didn’t seem like it, but our little ROV includes mathematics. We had to
measure out the PVC for the frame, keep track of our budget, and make sure to
have more thrust from the motors than drag from the water. In the regional
challenge, we had to prioritize to get the greatest amount of points for the
least amount of time. We used math to help us get more points.
Basic design before motors
When we first tested our ROV, the net had some problems. It was too low
to catch the balls easily and the lip that was supposed to hold the balls in
the net was not large enough to hold the balls in when driving around. On
top of that, there was almost no way to push golf balls on the bottom. We
had to problem solve and move our net up with zip-ties and adapt to our
working environment because we were at the cold outdoor testing pool and
not our school. We were able to add a small net at the bottom to push the
golf balls along the bottom. It had to be big enough to push them but small
enough not to affect catching the balls.
Uh-Oh! Broken Propeller
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During the orbs challenge at regionals, everything was going great until one
of the forward/backward motor’s propellers fell off! With some quick
thinking and superglue we were able to get the propeller back on and score
another four points.
It’s Alive! (Sort of….)
Testing motors
Final Design
THE TEAM
Isaac Avery
• Isaac has built a quadcopter from
scratch and learned soldering, wiring,
and that a computer can make it a lot
easier to fly
• He participated in SeaPerch in 2015
• He enjoys science, history, and math
at school
Gavin DePue
• Gavin participates in many
extracurricular activities and especially
likes flying quadcopters and RC
airplanes.
• He participated in SeaPerch in 2015
• He enjoys science, history, and math
at school
Boaty McBoatface
• Boaty is an essential member of the
team
• This is his first SeaPerch competition
• He enjoys swimming 
While building the ROV we learned new techniques such as using soldering
irons, testing control boxes, and cutting PVC. When we saw the challenge
video we processed that information and realized that making a boxy net
instead of the standard one attached to the bottom would be better
because the challenges were all centered around catching and releasing
balls. We also decided not to add a PVC arm because that would hinder
movement and none of the challenges required it.
APPLYING PHYSICS
With the help of Sir Isaac Newton, we know that physics is constantly affecting
our ROV. The motors force water to move one way, and the equal and opposite
reaction pushes the ROV in the other direction (his third law).
For the easiest steering, we had to make the force of flotation equal to the
force of gravity by cutting off the floats so it wouldn’t sink or float.
Without magnetism, our motors would not work and our ROV would stay
motionless.
Newton’s third law of motion
WE LEARNED
While building the SeaPerch our team gained some useful skills. For instance,
we learned how to test our switches and buttons with an ohmmeter. Neither of
us had done much with ohmmeters before, so we learned something new.
We also learned how the DC (direct current) motors on our ROV work
(explained in the applying engineering section). They are cool because they can
be made in almost any size and are able to be used in many different things
(cars, toys, SeaPerches, quadcopters).
Accessed May 2016, https://s-media-cache-ak0.pinimg.com/736x/1a/34/ea/1a34ea6135aaa8845aee12d329b78551.jpg
Engineering plays a huge role in the creation of our
SeaPerch. The motors use a magnetic field and a power
source to rotate. The power goes through a wire and then
a graphite carbon “brush” to a copper commutator. The
commutators switch the power from positive to negative,
so the coil of wire doesn’t stay in one place from the
magnetic force. Then it travels through that coil, and
because of the magnetic field, it rotates, along with an axle.
Normally there are lots of coils, which makes for a
smoother rotation.
Net Problems
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APPLYING ENGINEERING
CENTURY SKILLS
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CONTACT INFO
Team Members: Isaac Avery, Gavin DePue
Mentor: Dirk Avery
[email protected]
540.693.0352
School: Rodney E. Thompson Middle School
Teachers: Mr. Vann, Ms. Quail
75 Walpole Street
Stafford, VA 22554
Phone: 540.658.6420
Nuclear symbol, accessed May 2016, https://upload.wikimedia.org/wikipedia/commons/thumb/a/ae/Nuclear_symbol.svg/2000px-Nuclear_symbol.svg.png