Question 67 GLI03 - Master-LT 500-1600 GRT

The Correct Answer is A. ### Explanation for Option A (Correct) Option A, "V-shaped ripple with the point of the V pointing downstream," describes the characteristic visual signature of two opposing or converging currents meeting. When two currents (one flowing around each side of the middle bar) converge at the downstream end, they collide and force the water upwards, creating a stationary wave (or ripple). This wave is shaped like a 'V' or 'wake' because the flow is moving away from the point of collision, causing the point of the 'V' to face the direction of the flow (downstream). This V-shaped downstream-pointing ripple identifies the exact location of the current convergence (or "meet"). ### Why Other Options Are Incorrect **Option B) V-shaped ripple with the point of the V pointing upstream:** This phenomenon typically indicates a standing wave or ripple caused by an obstruction or feature *upstream* of the observer, where the flow is splitting around the obstruction. If two currents were meeting, the resulting V-shape would point downstream, not upstream. **Option C) A small whirlpool occurs upstream of the bar:** Whirlpools (eddies or boils) are usually associated with localized, turbulent flow caused by current separation, steep drops, or obstacles, often occurring *downstream* of obstructions or in deep holes. While turbulence is related to complex flow, a whirlpool upstream of the bar does not specifically indicate the convergence of two separate currents at the bar's downstream end. **Option D) A smooth patch of water:** A smooth patch of water (known as a slick) generally indicates very deep water, very slow surface velocity, or the immediate upstream edge of an obstruction where the flow is laminar (non-turbulent) before hitting the obstruction. It does not indicate the convergence and resulting turbulence created by two currents meeting.