Deck General · Righting Arm & GZ Curve
The righting arm (GZ) is defined as:
- AThe vertical distance from the keel to the metacenter
- BThe horizontal distance between the vertical through G and the vertical through B when the vessel is heeled✓ Correct
- CThe distance from G to the waterline at any angle of heel
- DThe metacentric height multiplied by the sine of the heel angle
Explanation
GZ is the perpendicular distance between the line of action of buoyancy (through B') and the line of action of gravity (through G). The righting moment = displacement x GZ. At small angles, GZ ≈ GM x sin(heel).
Authority: Stability & Trim (USCG deck topic)
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