What is the buoyant condition of a semi-submersible vessel when loaded with cargo?

2025-04-30


The semi-submersible is floating when loaded with cargo. The specific analysis is as follows.
Floating and sinking state judgment based on

According to the conditions of floating and sinking of objects, when the hull is partially immersed in the water but still able to maintain the overall balance, its buoyancy is equal to the total gravity, which is in the floating state at this time.
Semi-submersible ship in loading cargo, although the deck will dive below the surface of the sea, but the building of the ship building is still exposed to the water, indicating that it is not completely sunk, in line with the definition of floating.
Physical Principle Verification

By adjusting the amount of seawater in the ballast water tank, the total gravity of the semi-submersible ship and the buoyancy of the discharged seawater to reach equilibrium, i.e., F float = G total and thus stays afloat.
If heavier cargo is loaded, more ballast water needs to be discharged to reduce its own gravity, ensuring that the total gravity remains equal to the buoyancy.
For example, China's largest semi-submersible ship, the Xinguanghua, uses this mechanism to transport large equipment.