Eleanor Roosevelt High School

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Eleanor Roosevelt High School 1st Annual Mustang
Regatta Winners
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Eleanor Roosevelt High School 2nd Annual Mustang
Regatta Winners
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Cardboard Boat Materials
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Cardboard Boat Physics

• How deep will it sink? It depends on the amount
  of water you displace

Displaced Volume of Water (V) V L x W x H
Boat
Displaced Water
Water
Water Displaced(ft3) Weight-of-boat--people-lb
s 62.4 lbs/ft3-H20 Depth(ft) boat sinks
Water Displaced(ft3) Length X Width of
boat (ft2)
Weight of Water 62.4 pounds/cubic-foot
Example Box boat, 3 ft X 6 ft, 1ft tall
(high) Boat area 3 X 6 18 ft2Weight of
boat 30 lbs Weight of 4 people 600 lbs
Water
displaced 630lbs ? 62.4 lbs/ft3 10 ft3

Depth it sinks 10ft3 ? 18 ft2 0.56 ft ? 12
in/ft 6.7 inches
Boat will ride with about 5.3
inches out of the water
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Cardboard Boat Physics
Generally, the wider your boat, the more stable
it is. why a boat tips over shapes of hulls and
stability secondary stability
Center-line
Center-line
Center-of-gravity
Center-of-gravity
Center-of-buoyancy
Center-of-buoyancy
Righting-Arm (Moment)
Righting-Arm (Moment)
POSITIVE
NEGATIVE
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Cardboard Boat Physics

• Boat Building tips1 Freeware boat designer
• Some real designs and discussion

Slanted Box
SimpleBox
V-Shaped Bow
Pontoon Design
Outrigger Design
RaftDesign
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Cardboard Boat Physics
According to Newtons 1st Law, on object is lazy
and will tend to want to keep doing what it is
already doing unless a net force acts on it. So
you will need a net force to get your boat to
start moving and a net force to turn it around.
This is difficult because without sturdy paddles
it is hard to push and pull water. The
gravitational force on a cubic foot of water is
62.4lbs. That is very difficult to push aside
because it has a lot of inertia.
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Cardboard Boat Physics
According to Newtons 2nd Law, an objects
acceleration is directly proportional to the net
force acting on it and inversely proportional to
its mass. This means that if you exert a lot of
force it is likely that your boat will accelerate
to a higher speed. Likewise, if your boat is less
massive, you can exert less force to accelerate
it to a greater speed. To find out more about
this you can look up Newtons 2nd Law and
kayaking or canoeing. Physics of Kayaking
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Cardboard Boat Physics
According to Newtons 3rd Law, every force is a
single interaction between 2 objects. So, if you
want your boat to move forward, you must cause
your oar to exert a force on the water, then the
water exerts a force back on the oar causing the
boat to move forward or sideways. The boat
usually moves in the opposite direction to the
force you exert. For more information about this
look up how to paddle a canoe and the physics of
paddling a canoe. physics of paddling how to
paddle
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Cardboard Boat Design

• Set the Design Goal Float, Turn, Fast, Looks
• Sketch out your design
• build a scale model from thin poster board (1in
  1ft)
• estimate materials or plan how to use what you
  have
• plan out what construction techniques will be
  used
• 1x1x3 box will float 187 lbs.
• If itll hold you, its big enough to float
• Flat bottoms (sit-to-paddle) are easiest to
  make, but can cause tipping problems.
• Rudders help keep you straight but adds
  complexity to your design.

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Cardboard Boat Design

• Short boats (lt8) - are difficult to keep
  straight
• Best Height 18 inches
• allows room to sit/kneel still paddle over the
  edge
• Best Width
• 18-30(max) for 1 person
• 48 wide for 2 people side by side
• Kneeling is a power position but sitting is
  more comfortable

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Construction Tips Techniques

• Cover edges of cardboard with cardboard they act
  like siphon
• Cardboard Tubes make great frames
• Cutting for joining bending
• Fastening tubes together
• Cardboard Hull
• Bottom 2-3 layers, fasten cover the seams
  w/cardboard
• Sides 2 layers
• Decorate with house paint
• Reinforce the area where you sit, kneel or stand

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Construction Tips Techniques

• Duct tape only non-painted surfaces (tubes or
  frame that will be covered)
• Duct tape shrinks when painted
• Duct tape can be covered with masking tape if you
  need to paint it.
• Clear tape - it melts when painted and does a
  horrible job of sealing cardboard. Dont use it!!
• Masking tape for edges seams, after overlapping
  with cardboard

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Steering can be a challenge
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Look at that power stroke by the Stars Stripes
Winner
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Why did they sink? Because of poor turning
technique too much buoyancy. They were riding
too high in the water, then when they turned they
leaned a little bit too far over started to
take in water
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Disqualified! You cannot use the lane markers to
help you pilot the boat!
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Celebrities sometimes show up, like Peter Pan,
Wendy, Tinker Bell, and Captain Hook
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Boat can have interesting decorations design
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Best Decorated Winner!
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Boat can be small still seaworthy
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Boats that do not have several layers of
cardboard that are overlapped at the edges and
corners can become misshapen take in water.
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Showing Mustang Pride, but oops, the oar was not
attached firmly enough to the handle and so it
became a little bit harder to pilot.
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Except for edges corners, insides can be left
bare cardboard. (Just dont get them wet)
You can tape the insides, but dont attach tubes
with tape, these fell off in the water
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The Kraken was a cool looking boat. However, the
boat suffered a small separation of the bottom,
on an edge not thoroughly attached nor reinforced
with extra cardboard. It also took in water, but
did not completely sink.
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This boat nearly sank because the tube edges were
not covered with cardboard, instead they sealed
them with duct tape. Duct tape is not the perfect
seal for a cardboard end. It should have been
covered with cardboard, then taped.
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House paint is an excellent sealant for
cardboard, making it very water resistant.
However, you cannot paint over duct tape. The
paint disintegrates the duct tape glue. You can
paint over masking tape. In fact it is made to be
painted over.
You can paint cardboard first, then assemble
boat. You can assemble with duct tape then
cover duct tape with masking tape before you
paint.
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Remember that you do not need to coat the boat
with duct tape. Duct tape and masking tape are
binding materials, not waterproofing materials.
Latex house paint on cardboard or on masking tape
over cardboard is a better waterproofing.
However, you can never expect paint to take the
place of cardboard and tape in construction and
binding materials.
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Be like the Pirate, and have a little fun with
this project.