Appendix C to Part 157 - Procedure for Determining Distribution of Segregated Ballast Tanks To Provide Protection Against Oil Outflow in the Event of Grounding, Ramming, or Collision
33:2.0.1.5.26.11.195.1.10 : Appendix C
Appendix C to Part 157 - Procedure for Determining Distribution of
Segregated Ballast Tanks To Provide Protection Against Oil Outflow
in the Event of Grounding, Ramming, or Collision
1. Source. The procedure for determining the distribution
of segregated ballast tanks contained in this appendix conforms to
Regulation 18, paragraphs 12-15 of the MARPOL Protocol.
2. Procedure. Protective location of segregated ballast
tanks, voids, and other spaces that do not carry cargo which are
within the cargo tank length is determined from the following:
Σ PAc + Σ PAs = J[Lt(B + 2D)] Where: PAc = the side shell area in
square meters based on projected molded dimensions for each
segregated ballast tank, void, or other space that does not carry
cargo and which complies with paragraph 2(b) of this appendix; PAs
= the bottom shell area in square meters based on projected molded
dimensions for each segregated ballast tank, void, or other space
that does not carry cargo and which complies with paragraph 2(b) of
this appendix; Lt = the length in meters between the forward and
after extremities of the cargo tanks; B = the maximum breadth of
the ship in meters measured amidship to the molded line of the
frame; and D = the molded depth in meters measured vertically from
the top of the keel plate to the top of the freeboard deck beam at
the side amidships. In tank vessels having rounded gunwales, the
molded depth is measured from the top of the keel plate to the
point of intersection of the molded lines of the deck and side
shell plating, the lines being extended as though the gunwale were
of angular design.
(a) Method of determining a value for J. (1) For tank
vessels for 20,000 DWT, J = 0.45.
(2) For tank vessels of 200,000 DWT or more:
(i) J = 0.30; or
(ii) J = the greater of 0.20, or
where: a
= 0.25 for tank vessels of 200,000 DWT. a = 0.40 for tank vessels
of 300,000 DWT. a = 0.50 for tank vessels of 420,000 DWT.
For values of DWT between 200,000 and 300,000 DWT, 300,000 and
420,000 DWT, and greater than 420,000 DWT, the value of “a” is
determined by linear interpolation.
Oc = as calculated in Appendix A of this part. Os = as calculated
in Appendix A of this part. OA = the allowable oil outflow meeting
§ 157.19(b)(1) of this part.
(3) For values of DWT between 20,000 and 200,000 DWT, the value
of “J” is determined by linear interpolation between 0.45 and 0.30
respectively.
(b) PAc and PAs: Criteria for determining the segregated
ballast tanks, voids, and other spaces that do not carry
cargo.
The following criteria are to be met for a segregated ballast
tank, void, or space that does not carry cargo, to be used in
determining PAc and PAs:
(1) The minimum width of each wing tank or space, either of
which extends for the full depth of the vessel's side or from the
main deck to the top of the double bottoms is 2 meters or more. The
width is measured inboard from the vessel's side shell plating at
right angles to the vessel's center line. If a wing tank or space
has a width anywhere within it that is less than 2 meters, that
wing tank or space is not used when calculating PAc.
(2) The minimum vertical depth of each double bottom tank or
space is B/15 or 2 meters, whichever is smaller. If a double bottom
tank or space has a depth less than B/15 or 2 meters, whichever is
smaller, anywhere within it, the double bottom or space is not to
be used when calculating PAs.
(3) The minimum width of a wing tank or space is not measured in
the way of -
(i) the turn of the bilge area; or
(ii) a rounded gunwale area.
(4) The minimum depth of a double bottom tank or space is not
measured in the way of the turn of the bilge area.
[CGD 77-058b, 45 FR 43716, June 30, 1980, as amended by
USCG-2008-0179, 73 FR 35015, June 19, 2008]