The DEEP DRILLER is loaded as shown in the Sample Load Form #1 (Transit). Weather conditions require ballasting to survival draft. Assume that 4087 long tons of ballast are added at an average VCG of 8.32 feet, and upon arrival at 45 feet, port and starboard ballast tanks 1, 3, and 8 are slack. What is the new KGL?
• Effect of adding ballast on KG (vertical center of gravity) and understanding how to compute a new combined KG/KGL when weights are added • Using the moments about the keel method: (W₁×KG₁ + W₂×KG₂) ÷ (W₁ + W₂) • How slack tanks affect the free surface correction and therefore the final KGL
• Start from the original displacement and KG from Sample Load Form #1, then add 4087 LT at VCG 8.32 ft. How do you combine these to get a new KG before any free surface correction? • After you get the new KG, think about how slack ballast tanks (1, 3, and 8, both port and starboard) will change GM and therefore KG to become KGL. What additional correction must be applied? • Compare your final KGL with the choices: which values are too high or too low based on the fact that you are adding low ballast weight (VCG 8.32 ft) to a much higher original KG?
• Confirm the original displacement and KG on Sample Load Form #1 (Transit) before adding ballast • Carefully compute the total moment: existing moment + (4087 LT × 8.32 ft), and divide by the new total displacement • Apply the correct free surface correction for all slack tanks to convert KG to KGL, and only then compare with the answer choices
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