Question 52 GLI01 - Master-Unlimited Tonnage

The Correct Answer is C ### 2. Explanation of Why Option C is Correct: When a vessel moves from a warm climate to a cold climate, the **ambient temperature of the air and the ship's structure (hull and deck plating) drops significantly.** * **Initial Condition:** The air within the cargo hold is initially warm and carries a high amount of moisture (humidity), often picked up from the surrounding environment and potentially from the **hygroscopic cargo itself** (a hygroscopic cargo, such as grain or coffee, absorbs and releases moisture easily). * **The Cooling Effect:** As the ship sails into cold waters, the outside shell plating and structure cool down rapidly. This cool structure then cools the air immediately adjacent to it inside the hold. * **Dew Point Reached (Ship Sweat):** When this warm, moist air meets the cold structural surfaces, the temperature of the air drops below its dew point. This causes condensation to form directly on the ship's structure (underside of the deck, bulkheads, hull sides). This is known as **Ship Sweat** (or Hull Sweat). * **The Solution:** Ship sweat occurs because the hold air is too warm and moist relative to the ship’s structure. To prevent this, the hold air must be cooled down and replaced with cooler, drier outside air, or at least air that is cooler than the dew point of the initial hold air. **Ventilation** (constantly and vigorously) achieves this by drawing in the cooler outside air, reducing the temperature and moisture content inside the hold, and bringing the temperature of the hold air closer to the temperature of the ship’s structure, thereby preventing condensation on the cold metal. ### 3. Explanation of Why Other Options Are Incorrect: **A) There is danger of heavy cargo sweat if you ventilate.** * **Incorrect:** Cargo sweat (condensation forming directly on the cargo itself) typically occurs when the cargo is significantly *cooler* than the surrounding hold air. In this scenario (warm to cold climate), the structural cooling is rapid, but the large mass of hygroscopic cargo retains its heat longer. The surrounding air is becoming *colder* due to the environment, while the cargo is relatively *warmer*. Introducing cooler air via ventilation helps cool down the warm, moist hold air, minimizing the risk of this air reaching the cold dew point of the cargo (which is still warm). Ventilation is the defense against the immediate danger (ship sweat). **B) You should ventilate; there is little danger of ship sweat, but a possibility of cargo sweat.** * **Incorrect:** This is fundamentally wrong. When moving from warm to cold, **ship sweat is the primary and immediate danger**. The rapid cooling of the hull structure interacting with the warm, moisture-laden air creates ideal conditions for condensation on the cold steel. **D) There is little danger of any sweat problem.** * **Incorrect:** This move (warm to cold, with hygroscopic cargo) creates one of the highest risks for condensation and damage (specifically ship sweat). Without intervention (ventilation), heavy damage is highly probable.