[Code of Federal Regulations]
[Title 33, Volume 2]
[Revised as of July 1, 2003]
From the U.S. Government Printing Office via GPO Access
[CITE: 33CFR157.21]

[Page 467]
 
                TITLE 33--NAVIGATION AND NAVIGABLE WATERS
 
   CHAPTER I--COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED)
 
PART 157--RULES FOR THE PROTECTION OF THE MARINE ENVIRONMENT RELATING TO 
TANK VESSELS CARRYING OIL IN BULK--Table of Contents
 
             Subpart B--Design, Equipment, and Installation
 
Sec. 157.21  Subdivision and stability.

    A new vessel that is a U.S. vessel must meet the following 
subdivision and damage stability criteria after assuming side and bottom 
damages, as defined in Appendix B of this Part. A U.S. vessel that meets 
the requirements in this section is considered by the Coast Guard as 
meeting 46 CFR 42.20-5.
    (a) The final waterline, taking into account sinkage, heel, and 
trim, must be below the lower edge of an opening through which 
progressive flooding may take place, such as an air pipe, or any opening 
that is closed by means of a weathertight door or hatch cover. This 
opening does not include an opening closed by a:
    (1) Watertight manhole cover;
    (2) Flush scuttle;
    (3) Small watertight cargo tank hatch cover that maintains the high 
integrity of the deck;
    (4) Remotely operated watertight sliding door; or
    (5) Side scuttle of the non-opening type.
    (b) In the final stage of flooding, the angle of heel due to 
unsymmetrical flooding must not exceed 25 degrees, except that this 
angle may be increased to 30 degrees if no deck edge immersion occurs.
    (c) For acceptable stability in the final stage of flooding, the 
righting lever curve must have a range of at least 20 degrees beyond the 
position of equilibrium in association with a maximum residual righting 
lever of at least 0.1 meter. For the calculations required in this 
section, weathertight openings or openings fitted with automatic 
closures (e.g., a vent fitted with a ball check valve), need not be 
considered as points of downflooding within the range of residual 
stability, but other openings must be accounted for in the calculation.

[CGD 74-32, 40 FR 48283, Oct. 14, 1975, as amended by CGD 75-240, 41 FR 
54180, Dec. 13, 1976]