According to the 1912 International Navigational Congress recommendations used in harbour engineering, the entrance reach ratio of ship length to channel width for cargo vessels should lie approximately within which range?

Introduction / Context:
Entrance geometry standards ensure vessels can safely enter and exit harbours with adequate clearance and controllability. Historical recommendations from the International Navigational Congress (1912) are often cited in exams to benchmark preliminary channel sizing, before modern simulation-based checks are applied.

Given Data / Assumptions:

• Vessel class considered: cargo ships (distinct from passenger vessels).
• Parameter: ratio of ship length to entrance width.
• Application: preliminary sizing and rule-of-thumb verification.

Concept / Approach:
Cargo vessels typically require a somewhat narrower ratio range than passenger vessels due to differences in hull form, speed, and manoeuvring characteristics. The recommended range commonly quoted for cargo vessels is about 7.4–7.8:1, providing a workable compromise between berth protection and navigational safety.

Step-by-Step Solution:
Identify the vessel class (cargo) to avoid confusion with passenger-vessel ratios.Recall the historically cited range for cargo ships: about 7.4–7.8:1.Select the option matching this range exactly.

Verification / Alternative check:
Standard harbour-engineering MCQs and summaries of the 1912 recommendations list 7.4–7.8 as typical for cargo vessels, with passenger vessels having a larger ratio.

Why Other Options Are Wrong:

• 5.5–6.0 and 6.2–6.8 are narrower than recommended; they risk restricted manoeuvring margins.
• 8.2–8.5 corresponds more to finer, faster passenger ships.
• 7.0–7.2 is not a standard cited bracket.

Common Pitfalls:
Mixing up cargo and passenger ratios; applying the range without considering local wind, current, and tug assistance in modern design.

Final Answer:
7.4 and 7.8 to 1