🔍 Key Concepts

• Fuel consumption vs. speed relationships for displacement vessels • How fuel use often relates to speed squared or speed cubed in exam-type problems • Setting up a ratio/proportion using known and unknown fuel rates

💭 Think About

• First decide what mathematical relationship the problem expects between speed and fuel consumption. Is it directly proportional to speed, or to speed squared, or something else? • Write a simple formula that links fuel consumption per day to vessel speed, then plug in the original condition (268 bbl at 19 kn). • Use that same formula to solve for the new fuel consumption at 15 kn, and compare your result to the choices.

✅ Before You Answer

• Be clear whether you are assuming fuel consumption ∝ speed^2 or fuel consumption ∝ speed^3 (typical exam assumption for displacement hull resistance). • Recheck your calculation of the proportionality constant using 268 bbl/day at 19 kn before applying it to 15 kn. • After computing the new fuel rate, confirm that it is less than 268 bbl/day but still reasonable for only a 4-knot speed reduction.