🔍 Key Concepts
• On standard engineering or ship construction drawings, a centerline is usually drawn as a thin line made up of alternating long and short dashes.
• A hidden detail or invisible edge is usually shown with evenly spaced dashes of medium thickness, not the same pattern as a centerline.
• A dimension line typically has arrowheads and a numerical value between them, which is different from a pure centerline symbol.
💭 Think About
• Look at which of the labeled lines is made of an alternating long‑dash/short‑dash pattern rather than all solid or all evenly dashed.
• Ask yourself which line type would logically be used to show the center of symmetry of a hull, shaft, or cylinder on a plan view.
• Which choices can you eliminate right away because they are either completely solid, include arrowheads and measurements, or use dashes that are all the same length?
✅ Before You Answer
• Verify that the correct choice is a thin line, not thick or medium, since centerlines are normally drawn light and fine.
• Confirm that the dash pattern is long dash – short dash – long dash repeating, not just evenly spaced dashes.
• Make sure the option you select does not have arrowheads, numbers, or other dimensioning symbols attached.