(a) Defined. “Uppermost complete deck” means the uppermost deck which extends from stem to stern and from side to side at all points of its length and is bound by the vessel's hull.

(b) Restrictions. The uppermost complete deck must not:

(1) Extend above any space exempted as open space under paragraph (d) of § 69.117;

(2) Extend below the design waterline, except in the case of vessels such as submersibles, where the entire uppermost complete deck is submerged during normal operations; or

(3) Rest directly on consecutive or alternating ordinary bottom frames or floors for a distance of over one-half of the tonnage length.

(c) Deck discontinuities. Decking athwartships of the following deck discontinuities is not considered to be part of the uppermost complete deck:

(1) Through-deck openings that are not protected from the sea and the weather, such as would be provided by hatch covers or a surrounding superstructure that encloses the opening and whose area is more than 10 percent of the total deck area from stem to stern as viewed from above.

(2) Middle line openings conforming to the requirements of § 69.117(e)(2).

(3) Deck recesses that are not through-hull for which the depth of the deck recess at its deepest point is more than five feet below adjacent portions of the deck, and whose area (as viewed from above) is more than 10 percent of the total deck area from stem to stern, as viewed from above.

(4) Notches bounded by a deck below that wrap around from the ends to the sides of the vessel for which the depth at the deepest point is more than five feet below adjacent portions of the deck, the area is more than one percent of the total deck area from stem to stern as viewed from above, the length of the notch in the direction of the vessel's longitudinal axis exceeds 10 feet at any point across its width, and the width of the notch in the direction of the vessel's longitudinal axis exceeds two feet at any point along its length.