Question:medium
Which ONE of the following options CORRECTLY matches the efficiencies in Column 1 with the corresponding definitions in Column 2?
Column 1 Column 2 I Gear efficiency P Ratio of delivered power to shaft power II Shaft efficiency Q Ratio of shaft power to brake power III Hull efficiency R Ratio of thrust power to delivered power IV Propeller (behind-hull) efficiency S Ratio of effective power to thrust power
Which ONE of the following options CORRECTLY matches the efficiencies in Column 1 with the corresponding definitions in Column 2?
| Column 1 | Column 2 | ||
|---|---|---|---|
| I | Gear efficiency | P | Ratio of delivered power to shaft power |
| II | Shaft efficiency | Q | Ratio of shaft power to brake power |
| III | Hull efficiency | R | Ratio of thrust power to delivered power |
| IV | Propeller (behind-hull) efficiency | S | Ratio of effective power to thrust power |
Show Hint
Trace the power chain from brake power at the engine down to effective power at the hull, one link at a time.
Updated On: Jul 28, 2026
- I-Q; II-P; III-S; IV-R
- I-P; II-S; III-R; IV-Q
- I-P; II-R; III-Q; IV-S
- I-S; II-R; III-Q; IV-P
Show Solution
The Correct Option is A
Solution and Explanation
Step 1: Write the power chain in order.
Power leaves the engine as brake power $P_B$, passes through the gearbox to become shaft power $P_S$, travels along the shafting to become delivered power $P_D$ at the propeller, gets turned by the propeller into thrust power $P_T$, and finally moves the hull as effective power $P_E$.
Step 2: Attach one efficiency to each link.
$P_S / P_B$ is the gear efficiency, the only step between brake power and shaft power, so it is Q. $P_D / P_S$ is the shaft efficiency, the step from shaft power to delivered power, so it is P. $P_T / P_D$ is the propeller (behind-hull) efficiency, turning delivered power into thrust, so it is R. $P_E / P_T$ is the hull efficiency, turning thrust power into effective power, so it is S.
Step 3: Match each roman numeral.
I (Gear) needs Q, II (Shaft) needs P, III (Hull) needs S, IV (Propeller, behind-hull) needs R.
Final Answer:
The set I-Q, II-P, III-S, IV-R is option A. \[ \text{Correct option} = A \]
Power leaves the engine as brake power $P_B$, passes through the gearbox to become shaft power $P_S$, travels along the shafting to become delivered power $P_D$ at the propeller, gets turned by the propeller into thrust power $P_T$, and finally moves the hull as effective power $P_E$.
Step 2: Attach one efficiency to each link.
$P_S / P_B$ is the gear efficiency, the only step between brake power and shaft power, so it is Q. $P_D / P_S$ is the shaft efficiency, the step from shaft power to delivered power, so it is P. $P_T / P_D$ is the propeller (behind-hull) efficiency, turning delivered power into thrust, so it is R. $P_E / P_T$ is the hull efficiency, turning thrust power into effective power, so it is S.
Step 3: Match each roman numeral.
I (Gear) needs Q, II (Shaft) needs P, III (Hull) needs S, IV (Propeller, behind-hull) needs R.
Final Answer:
The set I-Q, II-P, III-S, IV-R is option A. \[ \text{Correct option} = A \]
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