🔍 Key Concepts
• Six degrees of freedom of ship motion: surge, sway, heave, roll, pitch, yaw
• Meaning of directional (course) stability vs transverse/longitudinal stability
• Which motion is around the vertical axis as shown in the illustration
💭 Think About
• From the drawing, match each motion (pitch, sway, yaw, surge) to the axis it acts about or along
• Ask yourself: which kind of motion would make the bow wander left and right from its intended course?
• Eliminate the motions that only move the ship up/down or fore-and-aft without changing heading
✅ Before You Answer
• Be clear on the difference between rotational motions (roll, pitch, yaw) and translational motions (surge, sway, heave)
• Identify which motion directly changes the vessel’s heading/course rather than just its position
• Verify on the illustration which motion is specifically tied to the vertical axis