activity page will offer:
An exploration of one theory for the Hunley sinking
definition of a sealing gasket
metal jar lids
thick rubber bands
rubber glove (or swatch of rubber material)
or tub filled with water
activity, you'll explore the mechanics of waterproofing a seal.
Instead of a submarine hatchway, two metal lids will be "sealed"
together using rubber bands. You'll compare and contrast the effectiveness
of a metal-to-metal seal versus one that uses a rubber gasket.
- Clean and dry four identical metal lids. Then, position two
of the lids so that the rims align against each other. When the
rims are face to face they will creating an enclosed hollow space.
- Secure the positions of these two lids with two thick rubber
bands. The bands should be placed at a 90 degree angle to each
other to insure a uniform seal.
- Obtain a discarded rubber glove or a swatch of thin rubber material.
Place one of the unused lids over the material and trace the outline
of the rim onto the rubber.
- Use a compass to draw two additional circles using the center
of this traced outline. One circle should have a diameter about
1 inch (2.5 cm) less than the traced image. The other circle should
have a diameter about 1 inch more than the traced circle.
- Use scissors to cut out the ring or rubber material that lies
between the outermost and innermost circle. This ring will become
the sealing gasket for the two lids.
- Repeat steps 1 and 2. (You may be better off just repeating
these steps using the unused lids) This time, however, insert
the rubber seal between the two rims. Be sure that the gasket
remains in place when the lids are secured together with the rubber
- Place both lid systems in a sink or tub filled with water. To
prevent the lids from floating, you may need to place a fishing
weight over each lid system. Let stand for several minutes.
- Carefully remove the lids and dry off any water from the outside
of each set-up. Separate the lids and observe the appearance of
the inside of each system. Did water enter either system? Explain
- What was the role of the ring of rubber material?
- Although the lids were metal, both setups were very buoyant.
- What was the role of the fishing sinkers?
- Predict the buoyancy of each lid system over time.
Visualizing the Concept
A rubber gasket produces a waterproof seal by filling in the tiny
pits of unmatched surfaces. Its expansion into these surface irregularities
prevents water from flowing through minute metal-to-metal gaps.
Can you envision the action of such a gasket? If so, illustrate
it in two drawings that show a magnified view of metal surfaces
in close contact. One view should illustrate the bare interface
of bare metal. The other view should show the exact same surfaces
(with identical pitting and surface irregularities), but aligned
against a common rubber gasket
The space shuttle Challenger was another vessel that met her demise
due to faulty seals. The seals that failed on the Challenger, however,
were o-rings inserted between adjoining segments of the solid rocket
boosters. Research this disaster and compare and contrast the failing
of the seals in both losses.
Did you know that water entering the hull of a ship is a common
occurrence. That is why most ships have bilge pumps. These devices
pump any water that has entered the hull out into the surrounding
sea. Contact a local boat supplier or do a web search to learn more
about bilge pumps. Could such a pump have saved the Hunley? How
would it operate? How would it differ from the ballast pumps? Explain.
of the Hunley - Inside the Hunley
An interactive panorama of the inside of the submarine hull
Friends of the Hunley - Recovery
Information about the recovery of the submarine
in the Hunley http://home.att.net/~JVNautilus/Hunley/Hunleyarchaeology.html
Site that illustrates the hatchways and locking systems employed
to keep the hull watertight.
activities in this guide were contributed by Michael DiSpezio, a
Massachusetts-based science writer and author of "Critical Thinking
Puzzles" and "Awesome Experiments in Light & Sound" (Sterling Publishing
Academic Advisors for this Guide:
Corrine Lowen, Science Department, Wayland Public Schools, Wayland,
Suzanne Panico, Science Teacher Mentor, Cambridge Public Schools,
Anne E. Jones, Science Department, Wayland Middle School, Wayland,
Gary Pinkall, Middle School Science Teacher, Great Bend Public Schools,
Great Bend, KS