Question 60 OSV01 - Master/Chief Mate - Offshore Supply Vessels

The Correct Answer is B **Explanation of Option B (Correct):** When docking an oceangoing single-screw vessel (which typically has limited maneuverability, especially at low speeds, and relies on propeller wash and rudder action) under normal circumstances with a single tug, the primary and most critical function of the tug is **to control the bow**. The bow is the most difficult part of the vessel to control, especially against wind and current, and is often the first part to be caught by external forces. By placing the tug tied to the **offshore bow** (the side away from the dock), the tug can hold the bow off the dock, push it toward the dock, or act as a pivot point, allowing the ship's main engine and rudder to control the stern movement while the ship slides smoothly into the berth. This configuration gives the docking master precise control over the vessel's angle of approach. **Explanation of Other Options (Incorrect):** * **A) To pull the vessel into the slip and is tied to the bow:** While the tug is tied to the bow, its primary function is usually not just to *pull* the entire ship into the slip (the main engine often handles longitudinal movement). More importantly, the critical need is *control* of the bow angle, not just brute pulling power. * **C) To push the ship bodily alongside and is tied to the offshore side on the stern:** Pushing the ship bodily alongside (sidelining) is a function often performed by multiple tugs or specialized harbor tugs, but it is not the *usual* primary function of a single tug assisting a single-screw vessel during docking. Furthermore, controlling the stern with a single tug is less critical than controlling the bow, as the ship's propeller wash and rudder have more direct control over stern movement. * **D) To control the stern and is tied to the stern on the offshore side:** This is generally inefficient. If the stern is controlled but the bow is loose, the bow will immediately drift, making the docking impossible or dangerous. The vessel's own engine and rudder offer the best control for the stern; the tug is needed where the vessel has the least control—the bow.