[Code of Federal Regulations]
[Title 46, Volume 7]
[Revised as of October 1, 2003]
From the U.S. Government Printing Office via GPO Access
[CITE: 46CFR172.090]

[Page 149-150]
 
                           TITLE 46--SHIPPING
 
   CHAPTER I--COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED)
 
PART 172--SPECIAL RULES PERTAINING TO BULK CARGOES--Table of Contents
 
Subpart E--Special Rules Pertaining to a Barge That Carries a Hazardous 
           Liquid Regulated Under Subchapter O of This Chapter
 
Sec. 172.090  Intact transverse stability.

    (a) Except as provided in paragraph (b) of this section, each tank 
barge must be shown by design calculations to have a righting arm curve 
with the following characteristics:
    (1) If the tank barge is in river service, the area under the 
righting arm curve must be at least 5 foot-degrees (1.52 meter-degrees) 
up to the smallest of the following angles:
    (i) The angle of maximum righting arm.
    (ii) The downflooding angle.
    (2) If the tank barge is in lakes, bays and sounds or Great Lakes 
summer service, the area under the righting arm curve must be at least 
10 foot-degrees (3.05 meter-degrees) up to the smallest of the following 
angles:
    (i) The angle of maximum righting arm.
    (ii) The downflooding angle.
    (3) If the tank barge is in ocean or Great Lakes winter service, the 
area under the righting arm curve must be

[[Page 150]]

at least 15 foot-degrees (4.57 meter-degrees) up to the smallest of the 
following angles:
    (i) The angle of maximum righting arm.
    (ii) The downflooding angle.
    (b) If the vertical center of gravity of the cargo is below the 
weather deck at the side of the tank barge amidships, it must be shown 
by design calculations that the barge has at least the following 
metacentric height (GM) in feet (meters) in each condition of loading 
and operation:
[GRAPHIC] [TIFF OMITTED] TC01MR91.025

where--

K=0.3 for river service.
K=0.4 for lakes, bays and sounds and Great Lakes summer service.
K=0.5 for ocean and Great Lakes winter service.
B=beam in feet (meters).
fe=effective freeboard in feet (meters).

    (c) The effective freeboard is given by--

fe=f + fa ; or
fe=d, whichever is less.

where--
f=the freeboard to the deck edge amidships in feet (meters).
fa=(1.25)(a/L)((2b/B)-1)(h); or
fa=h, whichever is less.

where--

a=trunk length in feet (meters).
L=LOA in feet (meters)
b=breadth of a watertight trunk in feet (meters).
B=beam of the barge in feet (meters).
h=height of a watertight trunk in feet (meters).
d=draft of the barge in feet (meters).

    (d) For the purpose of this section, downflooding angle means the 
static angle from the intersection of the vessel's centerline and 
waterline in calm water to the first opening that does not close 
watertight automatically.