🔍 Key Concepts

• Relationship between speed and fuel consumption for displacement vessels (fuel use ~ speed³) • How to set up a proportion using the cube of the speed ratio • Checking if the final fuel rate seems reasonable compared to the original 8 tons/hour

💭 Think About

• What happens to fuel consumption when speed increases from 15 to 20 knots—does it rise in a straight line, or faster than that? • How can you use the ratio (20/15) and a power (like squaring or cubing) to estimate the new fuel burn? • After you compute the new rate, is it just a little more than 8 tons/hour, or significantly more? What makes sense physically?

✅ Before You Answer

• Be sure you are using knots as speed consistently in your ratio (20/15). • Confirm that you apply the speed ratio to the power commonly used for fuel vs. speed on displacement hulls (not just first power). • Compare your final answer with 8 tons/hour and ask: Is this increase in fuel use plausible for a relatively small increase in speed?