Sample solution for Vertical Center of Gravity (VCG) problem M.V. Surveyor

You have 6 containers of ship stores each measuring 8'L by 4'B by 6'H and weighing 0.5 ton each. Each container is stowed on deck. What is the maximum VCG permitted of the remaining cargo if you are carrying rig water and load to maximum capacity? (See illustration D037DG, stability letter for M.V. Surveyor)

A. 1.06 feet (Incorrect)  B. 1.32 feet (Incorrect) C. 1.65 feet (Incorrect) D. 1.90 feet (Correct)

 

M/V Surveyor's Stability Letter  click to view

1) Paragraph 4. states that if you carry rig water, which according to the question you are, then the maximum weight of cargo without other below deck cargo or ballast is 35 tons.

2) Paragraph 3. states that the height above the main deck of the center of gravity of deck cargo shall not exceed 2.0 feet.

Therefore, according to paragraphs 3 and 4 the moment for maximum deck cargo load with a vessel carrying rig water is 70 foot-tons (35 tons x 2.0 feet).

The moment for the containers is 3.0 tons x 3.0' = 9 foot-tons.

3.0 tons = 6 containers x 0.5 tons each

3.0 feet = the height of each container is 6 feet. The vertical center of gravity of each

container is 3.0 feet.

Remaining Cargo = Max Load - Containers

VCG = Moment/Tons

VCG = 61 foot-tons/ 32 tons

VCG = 1.9   

Answer D. 1.90 feet (Correct)