Question 70 TV02 - Towing Vessels - Great Lakes and Inland

The Correct Answer is C ### Why Option C is Correct: **C) The vessel has a drag of not more than 2 to 3 feet** When a vessel is maneuvering in pack ice, it needs a slight positive stern trim (a small amount of drag) for optimal performance and safety. A small drag (typically 1 to 3 feet) ensures several key benefits: 1. **Propeller Protection:** The stern trim helps ensure the stern gland and the propeller tips are slightly deeper and better protected under the ice mass, reducing the risk of damage from milling ice chunks or refreezing water. 2. **Rudder Effectiveness:** A stern trim places the rudder deeper, improving steering effectiveness and control while maneuvering through resistance. 3. **Icebreaking/Clearing:** While the bow should do the primary work, a slight stern trim helps the vessel ride up slightly on the ice and then utilize its weight to break it efficiently, while ensuring the wake clears the broken ice pieces away from the hull sides and propellers. ### Why the Other Options are Incorrect: **A) The vessel is ballasted so the forefoot is near the surface** This condition (trimming significantly by the stern/lifting the bow) is generally dangerous for ice operations. It exposes the vulnerable bow structure, makes it harder for the vessel to ride up onto the ice to break it, and severely compromises propeller/rudder performance by making them too deep relative to the breaking zone. It would also increase the risk of the propellers impacting broken pieces being pushed under the hull. **B) The vessel is on an even keel** While operable, an even keel means the propeller and rudder protection is minimized. If the vessel pitches or rolls slightly, the propeller tips are much closer to the ice surface, increasing the risk of damage compared to a vessel with a slight drag. It is not the *best* condition. **D) The vessel is trimmed slightly by the head** Trimming by the head (negative trim) is generally undesirable in ice. It places the maximum draft forward, which can make the vessel sluggish, increase resistance, and, most critically, expose the propellers and rudder tips significantly to the ice mass by lifting them relative to the surrounding water level, increasing the likelihood of damage. It is opposite of the necessary trim for ice navigation.