An embodiment includes an open/non-closed hull collar assembly that is shaped to increase encapsulated volume of a hull. The hull collar assembly may include a hull collar structure and a foam module. The hull collar structure may include a gunwale, an outboard boundary, and an inboard boundary. The outboard boundary extends in an outward lateral direction from a lower hull portion and extends in a longitudinal direction from the lower hull portion such that at least a portion of the hull collar structure is at least partially included in a freeboard portion of a boat hull. The inboard boundary extends from the gunwale a portion of a distance to a deck such that the hull collar structure is at least partially open or non-closed to an inner hull volume. The foam module is comprised of a non-expansive, closed cell foam. The foam module is shaped for disposition within the hull collar structure.