🔍 Key Concepts

• Time of slack and reversal relative to a reference station (entrance to Delaware Bay) and inland locations like Philadelphia • Elapsed time and distance run at 12 knots from Chestnut St. toward sea • How current changes progressively along a river/estuary as the tide turns at the entrance

💭 Think About

• First, figure out how long after the ebb begins at the entrance you will pass each of the listed locations going downriver at 12 knots. Which one lines up with when the flood is expected to die out? • Think about whether the flood or ebb reaches the seaward end or the upriver end first. How does that affect where you will still have flood versus where it will already have turned to ebb? • Use the relationship between knots, nautical miles, and hours to estimate your position vs. time after departure, then compare that timing to the 1526 reversal at the bay entrance.

✅ Before You Answer

• Convert speed and time correctly: 12 knots = 12 nautical miles per hour and be careful with decimal hours vs. minutes • Verify approximate river mile positions of Chestnut St., New Castle, Reedy Island, Ship John Shoal, and Mile 44 relative to Philadelphia and the bay entrance • Check which choice is closest to the point where the flood would reasonably be ending for your position at the time you pass there, given that the ebb has already started at the entrance at 1526.