Question 64 TV01 - Towing Vessels - Oceans or Near Coastal

The Correct Answer is B ### Why Option B is Correct: Option B states, "The further forward and closer to amidships the more readily the tug will trip." This is correct because the risk of "tripping" (capsizing or experiencing a dangerous heeling moment) is directly related to the position of the towing bitts relative to the tug's center of gravity and hull geometry. 1. **Leverage and Heeling Moment:** When a tug is pulling and the tow line applies tension, that force creates a heeling moment (a force that tries to roll the vessel). This moment is calculated by multiplying the tension in the line by the perpendicular distance from the center of pull to the tug's center of gravity (or center of lateral resistance). 2. **Increased Tripping Risk:** If the towing bitts are placed far forward or close to the centerline (amidships), the effective leverage of the tow line when the tug is pulled sideways or subjected to a sudden side load (such as the line coming taut at a sharp angle) is significantly increased. 3. **The Pivot Point:** In standard towing practice, the bitts are placed well aft and often slightly outboard to ensure that if the tow line comes under extreme tension, the resulting force acts closer to the stern (the pivot point). If the bitts are moved forward, the tug's bow acts as a pivot, making the vessel much more unstable and susceptible to being rolled over or "tripped" if the line pulls abeam (sideways). ### Why Other Options Are Incorrect: * **A) The height and position of towing bitts has no significance.** This is definitively false. The position and height of the bitts are arguably the most critical design elements influencing a tug's stability and safety in towing operations, directly impacting the heeling moment and the danger of tripping. * **C) Placement further aft permits more effective pulling, better steering and eliminates the danger of tripping.** While placing the bitts further aft *does* permit more effective pulling, better steering, and *significantly reduces* the danger of tripping (this is standard safe practice), it does not *eliminate* the danger of tripping. Tripping remains a fundamental hazard in tug operations, though mitigated by proper design and operation. * **D) Installing the bitts down low lowers the center of gravity.** While installing any weight lower on the vessel nominally lowers the center of gravity (CG), the actual reduction in CG from lowering the bitts a small amount is negligible compared to the massive effect that the height of the bitts has on the *heeling moment*. A lower bitt position increases the potential moment arm between the tow line and the center of lateral resistance, which can sometimes increase the tripping danger, depending on the hull design and geometry. The primary concern is the leverage of the tow line, not the small change in the tug's inherent CG.