Which statement describes how two vessels should behave to minimize the venturi effect while passing alongside?

• A. Both vessels maintain their course
• B. Both vessels should turn away from each other
• C. Both vessels will maintain slight rudder towards each other
• D. One vessel should accelerate aggressively

Answer: (C)

When two vessels are passing closely alongside each other, the Venturi effect can occur, which involves a reduction in pressure that happens when the vessels create a constricted pathway for water between them. This effect can lead to troubling maneuverability or instability if not managed properly.

The correct practice for minimizing the Venturi effect is for both vessels to maintain slight rudder towards each other. This action essentially helps to balance the hydrodynamic forces at play as they approach one another. By turning towards one another, each vessel can create a more stable flow of water around them, which reduces the likelihood of significant pressure changes that could lead to interference with navigation or control of the vessels. This slight rudder adjustment helps ensure that both ships remain clear and maintain a safe distance while passing, as it counters the suction effect that might otherwise occur if they were to maintain a straight course or turn away.

While the other options may seem logical at first glance, they either do not effectively counter the Venturi effect or could exacerbate the situation by either maintaining a direct course (which may lead to instability) or accelerating aggressively, which could increase the risk of collision or loss of maneuverability.