(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 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................................ 0.60Accommodation spaces...................... 0.95Consumable 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.------------------------------------------------------------------------