The COASTAL DRILLER is loaded as shown in the sample load from #2 (preload). All of the preload is dumped with the exception of 50 kips in preload tank #28. What is the new LCG?
• Longitudinal Center of Gravity (LCG) and how it shifts when weights are added or removed • Using the LCG shift formula: New LCG = (Total moment ÷ Total weight) after the weight change • How removing a weight affects LCG depending on whether that tank’s LCG is forward or aft of the original LCG
• First, think about whether tank #28 is located forward or aft of the vessel’s original LCG from sample load #2. Will removing preload from there tend to move the LCG forward or aft? • When most of the preload is dumped, how do the total weight and total longitudinal moment change? Which direction does that push the LCG? • Compare the direction of LCG movement you expect with the numerical trend of the answer choices (which are slightly increasing aft). Which range of values matches the direction you reasoned out?
• Look up or recall the LCG position of preload tank #28 from the sample load #2 data sheet before doing any math • Recalculate: New total weight = (original total weight) − (preload dumped), and new total moment = (original total moment) − (weight dumped × LCG of tank #28) • After you compute the new LCG (moment ÷ weight), compare it with the original LCG from sample load #2 and ensure the shift direction (forward/aft) makes physical sense
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