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Difficulty: Very hardResolving Paradoxes and Discrepancies

In an effort to reduce operating expenses, a major maritime freight carrier replaced its entire fleet of traditional steel shipping containers with newly engineered carbon-fiber containers that are 25 percent lighter. The carrier anticipated a significant drop in fuel consumption because vessel displacement was reduced while payload volume per voyage remained identical. However, during the year following the complete container replacement, the average quantity of fuel consumed per ton-mile of freight transported across the carrier's ocean routes increased by nearly 6 percent. Which of the following, if true, most helps to resolve the apparent paradox described above?

  1. A
    The market price per gallon of marine heavy fuel oil increased steadily throughout the year following the container fleet replacement.
  2. Because the carbon-fiber containers were substantially lighter, vessels carrying them rode higher in the water, exposing a larger cross-section of the hull to surface winds and hydrodynamic turbulence that required significantly more engine power to maintain cruising speed.Answer
  3. C
    Rail transport providers carrying the carrier's containers on inland routes recorded a substantial drop in fuel usage per container-mile after switching to the carbon-fiber units.
  4. D
    The carbon-fiber containers were substantially more expensive to purchase and maintain than the steel containers they replaced.
  5. E
    Competing ocean freight carriers operating along the same international shipping lanes continued using standard steel containers throughout the same period.

Answer

The apparent paradox is resolved by the option explaining that lighter containers caused vessels to ride higher in the water, thereby increasing aerodynamic and hydrodynamic drag and forcing engines to burn more fuel to maintain standard speeds.
The correct answer identifies a secondary hydrodynamic consequence of the weight reduction: because the lighter containers reduced vessel draft, more of the ship's hull was exposed above the waterline. The resulting wind and surface turbulence resistance demanded increased engine output to sustain cruising speed, neutralizing the mass benefit and driving up fuel consumption per ton-mile.

Step-by-Step Solution

1
Identify the two seemingly contradictory facts in the stimulus.
Fact 1: Carbon-fiber containers are 25% lighter, reducing ship displacement with identical payload volume. Fact 2: Fuel consumed per ton-mile across ocean routes increased by 6% after replacing the containers.
Resolving a paradox requires finding a missing factor that allows both facts to be simultaneously true without denying either premise.
2
Evaluate the mechanism required to reconcile the premises.
The correct explanation must show how the reduction in container weight directly or indirectly caused an operational inefficiency that outweighed the expected energy savings.
A valid resolution introduces a third variable that accounts for the unexpected negative outcome resulting from the initial change.
3
Assess the correct choice against the required mechanism.
The statement regarding vessel draft explains that lighter weight caused ships to sit higher in the water, increasing exposure to wind and surface turbulence. Overcoming this extra drag required more engine power than was saved by the lower mass, explaining the 6% increase in fuel burn per ton-mile.
This logical bridge reconciles the 25% mass reduction with the 6% fuel consumption increase.

Key Concept

Resolving Paradoxes through Confounding Physical and Operational Side Effects
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Topics

Resolving Paradoxes and Discrepancies

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