What determines whether a vessel is in displacement or planing mode?

The determination of whether a vessel operates in displacement or planing mode primarily hinges on speed and the interaction of the hull with the water. In displacement mode, a vessel moves through the water by pushing it aside, which is typical at lower speeds. The hull maintains a consistent shape, and the water's surface tension keeps it afloat without significant changes in the angle or position of the vessel.

In contrast, when a vessel reaches higher speeds, it can transition into planing mode, where it begins to rise and skim across the water's surface rather than pushing it aside. This occurs when the speed is sufficient to generate enough lift, allowing the hull to significantly reduce drag, thereby enhancing efficiency and speed. This dynamic change in how the vessel displaces water is critical in distinguishing between the two modes of operation.

While factors like the weight of the vessel, the type of engine used, and the size of the hull do influence overall performance and design, it is the interaction of speed and the hull's behavior in the water that directly affects whether the vessel is in displacement or planing mode.