On 10 November 2023 at 2130, you are inbound...

On 10 November 2023 at 2130, you are inbound at Charleston Harbor Entrance Buoy “10” (ACT6611). Your vessel will transit 15nm and make good 12.5 knots to a berth where the nearest tidal current station is ACT6706. What will be the direction and velocity of the current as you approach the dock? Illustration D058NG

🔍 Key Concepts

• Use the Speed = Distance / Time formula to find how long it takes to go 15 nm at 12.5 knots. • Identify which tide current station (ACT6611 vs ACT6706) applies "as you approach the dock". • From the current graph, decide if the current at your ETA is flood (positive) or ebb (negative), then match that to the mean flood/ebb directions printed on the chart.

💭 Think About

• First, compute your ETA at the berth starting from 2130 using your transit time. What clock time do you get? • On the lower graph (ACT6706), at that ETA, is the curve above or below the zero line, and roughly how strong (in knots) does it look? • Once you know whether it is flood or ebb and the approximate speed, which choice has both a matching magnitude and a direction consistent with flood or ebb at ACT6706?

✅ Before You Answer

• Be sure you are reading the ACT6706 (Lower Town Creek Reach) graph for conditions at the berth, not ACT6611. • Confirm the ETA falls on 10 November and read the correct side of the time axis (make sure you’re not on 9 Nov or 11 Nov). • Match the sign of the current (flood vs ebb) to the printed Mean Flood Dir 335°(T) or Mean Ebb Dir 172°(T) at ACT6706 before selecting a choice.