[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: 46CFR174.310]

[Page 179-180]
 
                           TITLE 46--SHIPPING
 
   CHAPTER I--COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED)
 
PART 174_SPECIAL RULES PERTAINING TO SPECIFIC VESSEL TYPES--Table of 
Contents
 
       Subpart I_Hopper Dredges With Working Freeboard Assignments
 
Sec. 174.310  General.

    (a) Each hopper dredge under this subpart must be shown by design 
calculations based on the assumptions under paragraphs (b), (c), (d), 
and (e) of this section, that it meets--
    (1) The requirements in Sec. Sec. 170.170, 170.173, and 170.300 of 
this chapter in each condition of loading and operation; and
    (2) The survival conditions of Sec. 174.320 in each condition of 
loading and operation assuming the character and extent of damage 
specified in Sec. 174.315.
    (b) The calculations required by paragraph (a) of this section must 
assume:
    (1) The hoppers are full of seawater;
    (2) The permeability of flooded spaces is as provided by Table 
174.310;
    (3) The equalization provisions of Sec. 174.325; and
    (4) The jettisoning provisions of Sec. 174.330.
    (c) The calculations required by this section must take into account 
a sufficient number of loading conditions to

[[Page 180]]

identify the condition in which the vessel is least stable, including, 
but not limited to, the most severe loading condition, and the:
    (1) Specific gravity of the dredge spoil, from 1.02 up to and 
including the maximum required by paragraph (e)(1) of this section; and
    (2) Draft, up to and including the draft corresponding to the 
working freeboard for the full range of trim.
    (d) The calculations required by this section for a dredge with open 
hoppers may include spillage of spoil from the hopper resulting from 
changing the angle of heel and trim.
    (e) The following assumptions must be made when doing the 
calculations required by this section:
    (1) Dredged spoil in the hopper is a homogeneous liquid with a 
maximum specific gravity for the areas of operation.
    (2) When calculating the vessel's righting arm, it is assumed at 
each angle of heel that the vessel trims free and the trimming moment is 
zero.

             Table 174.310--Permeability of Floodable Spaces
------------------------------------------------------------------------
             Spaces and tanks                       Permeability
------------------------------------------------------------------------
Storerooms................................  0.60
Accommodation spaces......................  0.95
Consumable liquid tanks...................  0.00 or 0.95--whichever
                                             results in the more
                                             disabling condition.
Machinery space...........................  0.85--unless otherwise
                                             supported by calculations.
Cargo tanks...............................  Determined from the actual
                                             density and amount of
                                             liquid carried in the tank.
------------------------------------------------------------------------