[Code of Federal Regulations]
[Title 46, Volume 7]
[Revised as of October 1, 2004]
From the U.S. Government Printing Office via GPO Access
[CITE: 46CFR171.105]

[Page 137-138]
 
                           TITLE 46--SHIPPING
 
   CHAPTER I--COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED)
 
PART 171_SPECIAL RULES PERTAINING TO VESSELS CARRYING PASSENGERS--Table 
of Contents
 
              Subpart D_Additional Subdivision Requirements
 
Sec. 171.105  Double bottoms.

    (a) This section applies to each vessel that carries more than 12 
passengers on an international voyage and all other vessels that are--
    (1) 100 gross tons or more; and
    (2) In ocean or Great Lakes service.
    (b) Each vessel over 165 feet (50 meters) and under 200 feet (61 
meters) in LBP must have a double bottom that extends from the forward 
end of the machinery space to the fore peak bulkhead.
    (c) Each vessel over 200 feet (61 meters) and under 249 feet (76 
meters) in LBP must have a double bottom that extends from the fore peak 
bulkhead to the forward end of the machinery space and a double bottom 
that extends from the aft peak bulkhead to the aft end of the machinery 
space.
    (d) Each vessel 249 feet (76 meters) in LBP and upward must have a 
double bottom that extends from the fore to the aft peak bulkhead.
    (e) Each double bottom required by this section must be at least the 
depth at the centerline given by the following equation:

D=18.0+0.05(L) inches
D=45.7+0.417(L) centimeters

where--

D=the depth at the centerline in inches (centimeters).
L=LBP in feet (meters).

    (f) The line formed by the intersection of the margin plate and the 
bilge plating must be above the horizontal plane C, illustrated in 
Figure 171.105, at all points. The horizontal plane C is defined by 
point B, located, as shown in Figure 171.105, in the midships section.

[[Page 138]]

[GRAPHIC] [TIFF OMITTED] TC01MR91.024

    (g) A double bottom is not required in a tank that is integral with 
the hull of a vessel if--
    (1) The tank is used exclusively for the carriage of liquids; and
    (2) It is approved by the Commanding Officer, Marine Safety Center.
    (h) A double bottom is not required in any part of a vessel where 
the separation of main transverse watertight bulkheads is governed by a 
factor of subdivision less than or equal to 0.50 if--
    (1) The Commanding Officer, Marine Safety Center approves;
    (2) The vessel makes short international voyages; and
    (3) The vessel is permitted by Sec. 75.10-10 of this chapter to 
carry a number of passengers in excess of the lifeboat capacity.

[CGD 79-023, 48 FR 51017, Nov 4. 1983, as amended by CGD 88-070, 53 FR 
34532, Sept. 7, 1988]