🔍 Key Concepts

• Lock operations and how water moves when a lock is filled vs. emptied • How current sets and swirls along a lower guide wall • Risk from other traffic (upbound/downbound) vs. risk from changing currents

💭 Think About

• Think about where the water comes from and where it goes when a lock is being filled compared to when it is being emptied. Which one affects the downstream (lower) side the most? • When you are tied off to the lower guide wall, what kind of current or surge could cause your lines to part or your vessel to surge violently? • Compare the danger from a passing upbound or downbound vessel to the danger from sudden changes in current and turbulence created by lock operations. Which is more likely to put heavy strain on your mooring lines at the lower wall?

✅ Before You Answer

• Identify which end of the lock is associated with lower guide wall = downstream side • Decide whether the strongest current and turbulence on the lower side happens when the chamber is being filled or emptied • Verify which choice directly relates to current reaction at the lower end, not just vessel traffic direction