🔍 Key Concepts

• Definition of the fore perpendicular (FP) and aft perpendicular (AP) in ship construction • Meaning of the vertical plane midway between FP and AP (often called the midship plane or midship section) • How standard ship-drawing symbols try to suggest “center” or “middle” in plan or section views

💭 Think About

• First, picture the ship in profile: mark the FP at the stem and the AP at or near the rudder post. Now, where is the plane that lies exactly halfway between these two points, and what is that plane called? • Look at each symbol and ask: which one is most naturally associated with a midship or middle transverse plane, as opposed to a baseline, centerline, or a generic frame? • Try to recall or deduce what the other symbols might represent (for example, baseline, centerline, frame or station) so you can eliminate them and isolate the one for the midship plane.

✅ Before You Answer

• Be clear that the question is about a vertical transverse plane at mid-length, not the longitudinal centerline plane. • Confirm in your mind that midship plane/section is located at L/2 between FP and AP. • Before choosing, make sure the symbol you select is not one you recognize as baseline or centerline on ship plans.