26. A vessel behaves as if all of its weight is acting downward through the center of gravity, and all its support is acting upward through which point?

The buoyant force acts upward through the center of buoyancy, which is the geometric center of the submerged hull volume. This point represents the upward support balancing the vessel's weight, acting downward through the center of gravity. The keel, tipping center, and amidships center section are structural or geometric locations, not the point of action for the buoyant force.