[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: 33CFR157.09]

[Page 456-457]
 
                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. 157.09  Segregated ballast.

    (a) A new vessel of 70,000 tons DWT or more must have segregated 
ballast tanks that have a total capacity to allow the vessel to meet the 
draft and trim requirements in paragraph (b) of this section without 
recourse to the use of oil tanks for water ballast.
    (b) In any ballast condition during any part of a voyage, including 
that of lightweight with only segregated ballast, the vessel's drafts 
and trim must have the capability of meeting each of the following 
requirements:
    (1) The molded draft amidship (dm) in meters without taking into 
account vessel deformation must not be less than dm in the following 
mathematical relationship:

dm=2.0+0.02L
    (2) The drafts at the forward and after perpendiculars must 
correspond to those determined by the draft amidship as specified in 
paragraph (b)(1) of this section, in association with the trim by the 
stern of no more than 0.015L.
    (3) The minimum allowable draft at the after perpendicular is that 
which is necessary to obtain full immersion of the propeller.
    (c) The vessel may be designed to carry ballast water in cargo tanks 
during the condition described in Sec. 157.35.
    (d) Segregated ballast spaces, voids, and other noncargo-carrying 
spaces for a vessel of conventional form must be distributed:
    (1) So that the mathematical average of the hypothetical collision 
(Oc) and the hypothetical stranding (Os) outflows 
as determined by the application

[[Page 457]]

of the procedures in Sec. 157.19 and Appendix B is 80 percent or less of 
the maximum allowable outflow (OA) as determined by Sec. 
157.19(b)(1); and
    (2) To protect at least 45 percent of the sum of the side and bottom 
shell areas, based upon projected molded dimensions, within the cargo 
tank length. When the vessel design configuration does not provide for 
the spaces to be distributed to protect at least 45 percent of the side 
and bottom shell areas, the spaces must be distributed so that the 
mathematical average of the hypothetical collision (Oc) and 
the hypothetical stranding (Os) outflows, determined by 
application of the procedures in Sec. 157.19 and Appendix B, is a 
further 2 percent less than the maximum allowable outflow 
(Oa) for each 1 percent by which the shell area protection 
coverage required is not achieved.
    (e) A ballast space, void or other non-cargo-carrying space used to 
meet requirements in paragraph (d) of this section must separate the 
cargo tank boundaries from the shell plating of the vessel by at least 2 
meters.
    (f) A vessel of conventional form for application of this section 
has:
    (1) A block coefficient of .80 or greater,
    (2) A length to depth ratio between 12 and 16, and
    (3) A breadth to depth ratio between 1.5 and 3.5.
    (g) Segregated ballast spaces, voids, and other noncargo-carrying 
spaces for a vessel not of conventional form must be distributed in a 
configuration acceptable to the Coast Guard.

[CGD 74-32, 40 FR 48283, Oct. 14, 1975, as amended by CGD 74-32, 40 FR 
49328, Oct. 22, 1975; CGD 75-201, 41 FR 1482, Jan. 8, 1976]