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Activity: Design a Ship

NGSS Science and Engineering Practices:

NGSS Crosscutting Concepts:

Materials

  • Table 8.8
  • Heavyweight aluminum foil
  • Polymer modeling clay
  • Scissors
  • Tape
  • Bamboo skewers
  • Wax paper
  • Aquarium or other large container
  • Water
  • 300 pennies or other small weights
  • Scale or balance
  • Stopwatch
  • Ruler
  • Towels
  • Blow dryer
  • Large water bottle
Table 8.8. Model ship design (A) goals and (B) constraints
A. Model ship design goals
  1. Stay afloat with a large amount of cargo (tonnage by weight)
  2. Move quickly by wind power with and without cargo
  3. Stay afloat in rough weather conditions with and without cargo
B. Model ship design constraints
  1. Must weigh at least 5 g without cargo
  2. Must be less than 10 cm wide (to pass through narrow canals)
  3. Must have a draft of less than 5 cm (to safely navigate shallow harbors)
  4. You may use no more than the following provided materials in the construction of your model ship:
    1. One 20 x 20 cm sheet of aluminum foil
    2. 20 g of modeling clay
    3. One bamboo skewer
    4. One 10 x 10 cm sheet of wax paper
    5. Tape
    6. Pennies or other weights
  5. All cargo must remain dry during transport.
  6. Model ship may not touch the bottom of the aquarium.

Procedure

Safety Note: Do not allow the blow dryer or any of the electrical equipment to come in contact with water. Unplug all electrical equipment immediately after use.

 

A. Initial design conception and prototype construction

  1. Identify the design goals and constraints
    1. Carefully consider the ship design goals and constraints (Table 8.8). These factors are meant to simulate real design conditions in naval architecture and engineering.
    2. During your initial design process, ensure that all design goals and criteria have been addressed.
    3. Review the text on Archimedes’ principle (principle of floatation), buoyancy, ship design, and stability as needed to ensure your model ship will float.
       
  2. Sketch the design of your model ship.
    1. Write a list of the design features included in your model ship.
    2. Record notes on how to construct the model including a list of materials.
       
  3. Discuss your design plans with a partner or group.
     
  4. Revise your design as needed.
  5. Construct your model ship according to your sketched design and notes. Consider this first model as your prototype. A prototype is an early model used to test and modify a particular design. Check design constraints:
    1. Use a balance to measure the weight of your prototype.
    2. Ensure that your prototype weighs at least 5 g. Record the total weight.
    3. Use a ruler to ensure that your prototype meets all size constraints. Record all size dimensions of your prototype.

 

B. Prototype testing

  1. Fill the aquarium with water until it is at least 10 cm deep.
     
  2. To begin testing, gently place your prototype model ship on the water surface.
     
  3. Test prototype speed without cargo.
    1. Float the prototype on the water.
    2. Use the blow dryer to gently push the prototype across the aquarium. The blow dryer simulates wind.
    3. Test the maximum speed of your prototype by recording the time required for it to travel from one end of the aquarium to the opposite side.
    4. Record your prototype test observations.
    5. If the prototype sinks, carefully dry it before continuing onto the next test phase.
       
  4. Test prototype stability without cargo.
    1. Float the dry prototype on the water.
    2. Test the stability of your prototype by repeatedly submerging and lifting a water bottle at one end of the aquarium once every second. This steady, repeated movement simulates rough ocean conditions.
    3. Use a stopwatch to record the amount of time the prototype remains afloat on the water surface. Continue the test the stability of the prototype for up to one minute.
    4. Record your prototype test observations.
    5. If the prototype sinks, carefully dry it before continuing onto the next test phase.
       
  5. Test prototype maximum cargo load.
    1. Note how the prototype floats and balances on the water surface.
    2. Test the maximum cargo load of your prototype by carefully placing individual pennies or other weights inside the prototype hull. These weights will simulate cargo in your model ship.
    3. You may place the weights anywhere within the prototype to balance the weight evenly.
    4. Continue to add weights one-by-one until the prototype sinks to the bottom of the aquarium.
    5. Record the maximum number of weights held afloat by the prototype before sinking. This number is the maximum cargo load of the prototype.
    6. Record you prototype test observations.
    7. If the prototype sinks, carefully dry it before continuing on to the next test phase.
       
  6. Test prototype speed under maximum cargo load.
    1. Float the dry prototype on the water.
    2. Carefully add the maximum cargo load of weights to the prototype (determined in step 5).
    3. Repeat speed testing (step 3) on your prototype using a blow dryer.
    4. Record your prototype test observations.
    5. If the prototype sinks, carefully dry it before continuing on to the next test phase.
       
  7. Test prototype stability under maximum cargo load.
    1. Float the dry prototype on the water.
    2. Carefully add the maximum cargo load of weights to the prototype (determined in step 5).
    3. Repeat stability testing (step 4) on your prototype.
    4. Record you prototype test observations.

 

C. Design refinement.

  1. Assess how well your prototype met the design goals and constraints (Table 8.8). Review all observations and notes from your prototype testing. Pay particular attention to performance failures such as sinking or slow speed.
    1. Does your ship float properly at the desired speed?
    2. Design modifications that would help address performance failures.
       
  2. Modify the prototype according to your new designs. Attempt to increase the maximum cargo load, maximum speed, and overall stability of your model ship. Rebuild the model ship from raw materials if needed.
     
  3. Ensure that the final model ship meets all design constraints.
    1. Measure and record the weight of the model ship.
    2. Measure and record the size dimensions of the model ship.
       

D. Final product evaluation.

  1. Repeat all test phases described in part B using your final model ship.
     
  2. Record all test results and observations in detail.
     
  3. Determine the displacement volume of your model ship hull.
    1. Fill a small container with water. Mark the water volume level.
    2. Submerge the model ship hull up as deep as possible without sinking.
    3. Mark the new water volume level.
    4. Calculate the displaced water volume. This volume equals the model ship hull displacement volume.
       
  4. Present your final product evaluation results to your class.

 

Activity Questions: 
  1. Prototype testing
    1. Describe the performance of your prototype in each phase of testing.
    2. What design flaws did you identify in your initial prototype?
    3. How did you assess the performance of your design features? Provide examples of quantitative and qualitative measures you considered during this process.
       
  2. Model performance with and without cargo
    1. How was the performance of your final model ship affected by the cargo load?
    2. What is the purpose of ballast in real ships?
    3. How might the performance of our final model ship be improved under cargo load in future designs?
       
  3. Design refinement and final product evaluation
    1. How did you change your design to address design flaws?
    2. How did the performance of the final ship model compare to that of the prototype?
    3. How might you continue to improve the performance of your model ship in future designs?
       
  4. Compare model ship designs within your class.
    1. What are some design similarities shared among the fastest model ships?
    2. What design features are common among the model ships that were able to carry the greatest amount of cargo?
    3. How did your classmates optimize stability in their model ship designs?
       
  5. One design goal called for a ship that is stable in rough ocean conditions. Ship stability can be achieved through several design solutions.
    1. What is the difference between leverage stability and weight stability in ship designs?
    2. What do you think are the advantages and disadvantages of multi-hulled ships like catamarans?
       
  6. Ship draft depth
    1. What are the advantages of having a deep draft in a real ship?
    2. What are the disadvantages of having a deep draft in a real ship?
       
  7. Physics of ship design
    1. What is Archimedes’ principle? Explain it using language that is easily understood by a student one year younger than you (who has not yet taken this class).
    2. How did you apply Archimedes’ principle when designing the hull of your model ship?
    3. How does the displacement volume of the model ship hull and the overall model weight relate to how well it will float in water?
    4. Use Archimedes’ principle to calculate the predicted maximum cargo load for your final model ship. How does this predicted cargo load compare to the actual maximum cargo load from the final product evaluation (Part D)?

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Exploring Our Fluid Earth, a product of the Curriculum Research & Development Group (CRDG), College of Education. University of Hawaii, 2011. This document may be freely reproduced and distributed for non-profit educational purposes.