🔍 Key Concepts

• Waterplane area in ship stability refers to the 2D shape you see at the waterline when looking straight down on the vessel • The waterplane is formed where the water surface cuts through the vessel at the draft she is floating at • Think about what physical boundary of the ship meets the water surface to create that outline

💭 Think About

• If you look at a ship from above, what exactly forms the closed shape you see at the waterline—the ship’s frame, a reference plane, or the outer shell? • Is a waterplane something defined by abstract reference planes, or by where the real structure of the vessel meets the water? • Which option best describes the actual physical surface of the vessel that touches the water along the waterline?

✅ Before You Answer

• Make sure the choice you pick describes a real, physical boundary that can intersect with the water surface to form a closed curve • Eliminate answers that are purely reference planes and not actual ship structure • Visualize the waterline outline you’d trace with a pencil from directly above—what part of the vessel are you tracing along?