What effect can shifting cargo have on a vessel?

Shifting cargo can significantly affect a vessel's stability and safety. When cargo is moved from its original position, it alters the center of gravity and can lead to changes in the vessel's heel, which is the angle at which the vessel tilts to one side. If the cargo shifts too far or the redistribution results in the center of gravity moving beyond a critical limit, it can cause the vessel to heel excessively or even capsize. This precarious situation emphasizes the importance of securing cargo properly and maintaining a stable load distribution to ensure safe operation at sea.

The other options would not accurately reflect the dynamics involved in cargo shifting. For example, while shifting cargo may affect speed indirectly due to increased drag or changes in trim, it does not directly lead to a consistent decrease in speed. A scenario where it has no significant effect on stability overlooks the essential safety concerns related to shifting weight. Additionally, the statement that it improves navigation is misleading, as instability generally complicates navigation rather than enhances it.