On a vessel of 9,000 tons displacement there are two slack deep tanks of palm oil (SG .86). Each tank is 40 feet long and 30 feet wide. What is the reduction in metacentric height due to free surface with the vessel in sea water (SG 1.025)?

Correct Answer: Option B — .48 ft

Palm oil with a specific gravity of 0.86 creates a proportional free surface moment. Two deep tanks measuring 40'x30' on a 9,000-ton vessel generate a net reduction in metacentric height of 0.48 feet when floating in standard seawater.