46 CFR § 171.010 - Definitions.
(b) Deepest subdivision load line means the waterline that corresponds to the deepest draft permitted by the applicable subdivision requirements in this part.
(c) Equivalent plane bulkhead means a bulkhead that is -
(1) Used in lieu of a recessed or stepped bulkhead when doing the subdivision calculations required in this part; and
(2) Located as shown in Figure 171.010(a).
(d) Ferry means a vessel that -
(2) Has provisions only for deck passengers or vehicles, or both;
(3) Operates on a short run on a frequent schedule between two points over the most direct water route;
(4) Offers a public service of a type normally attributed to a bridge or tunnel.
(e) Freeing port means any direct opening through the vessel's bulwark or hull to quickly drain overboard water which has been shipped on exposed decks.
(g) Flush deck means a continuous weather deck located at the uppermost sheer line of the hull.
(h) International voyage has the same meaning provided for the term in § 70.05-10 of this chapter.
(i) Machinery space means, unless otherwise prescribed by the Commandant for unusual arrangements, the space extending from the molded base line to the margin line and between the main transverse watertight bulkheads bounding the following spaces:
(1) Each space containing main and auxiliary propelling machinery.
(2) Each space containing propulsion boilers.
(3) Each space containing permanent coal bunkers.
(j) Open boat means a vessel not protected from entry of water by means of a complete deck, or by a combination of a partial weather deck and superstructure which is seaworthy for the waters upon which the vessel operates.
(k) Passenger space means a space which is provided for the accommodation and use of passengers, other than a baggage, store, provision or mail room.
(l) Recessed bulkhead means a bulkhead that is recessed as shown by bulkhead B in Figure 171.010(b).
(m) Small passenger vessel means a vessel of less than 100 gross tons -
(2) That is chartered with the crew provided or specified by the owner or owner's representative and carrying more than 6 passengers;
(3) That is chartered with no crew provided or specified by the owner or owner's representative and carrying more than 12 passengers; or
(n) Short international voyage means an international voyage where -
(2) The total distance between the last port of call in the country in which the voyage began and the final port of destination does not exceed 600 nautical miles (1111 kilometers).
(o) Scupper means a pipe or tube of at least 30 millimeters (1.25 inches) in diameter leading down from a deck or sole and through the hull to drain water overboard.
(p) Stepped bulkhead means a bulkhead that is stepped as shown by bulkhead A in Figure 171.010(b).
(q) Well deck means a weather deck fitted with solid bulwarks that impede the drainage of water over the sides or an exposed recess in the weather deck extending one-half or more of the length of the vessel (LOD) measured over the weather deck.