CFR > Title 46 - Shipping > CHAPTER I—COAST GUARD, DEPARTMENT OF HOMELAND SECURITY > SUBCHAPTER S—SUBDIVISION AND STABILITY (parts 170 to 174) > PART 171—SPECIAL RULES PERTAINING TO VESSELS CARRYING PASSENGERS > SUBPART H—Drainage of Weather Decks (§171.130 to §171.155) > 171.150—Drainage of a vessel with a well deck.

171.150—Drainage of a vessel with a well deck.

(a) Each well deck on a vessel must be watertight.
(b) Except as provided in paragraphs (c) and (d) of this section, the area required for freeing ports in the bulwarks that form a well must be determined as follows:
(1) If a vessel operates on exposed or partially protected waters, it must have at least 100 percent of the freeing port area derived from table 171.150.
(2) If a vessel operates only on protected or partially protected waters and complies with the requirements in the following sections for a vessel that operates on exposed waters, it must have at least 50 percent of the freeing port area derived from table 171.150:
(i) The intact stability requirements of § 171.030 or 171.050 and § 171.170.
(ii) The subdivision requirements of § 171.040, 171.043, or 171.070.
(iii) The damage stability requirements of § 171.080.
(3) If a vessel operates only on protected waters, the freeing port area must be at least equal to the scupper area required by § 171.145(d) for a cockpit of the same size.
(c) The freeing ports must be located to allow rapid clearing of water in all probable conditions of list and trim.
(d) If a vessel that operates on exposed or partially protected waters does not have free drainage from the foredeck aft, then the freeing port area must be derived from table 171.150 using the entire bulwark length rather than the bulwark length in the after two-thirds of the vessel as stated in the table.
Table 171.150
Height of solid bulwark in inches (centimeters) Freeing port area 1,2
6(15) 2(42.3)
12(30) 4(84.7)
18(46) 8(169.3)
24(61) 12(253.9)
30(76) 16(338.6)
36(91) 20(423.2)
1 Intermediate values of freeing port area can be obtained by interpolation.
2 In square inches per foot (square centimeters per meter) of bulwark length in the after 2/3 of the vessel.
[CGD 85-080, 62 FR 51354, Sept. 30, 1997]