46 CFR §42.20-6

1. (a)Design calculations must be submitted that demonstrate that the vessel will remain afloat in the conditions of equilibrium specified in § 42.20-12 assuming the damage specified in § 42.20-11 as applied to the following flooding standards:
   1. (1)If the vessel is over 150 meters (492 feet) in length it must be able to withstand the flooding of any one compartment, except the machinery space.
   2. (2)If the vessel is over 225 meters (738 feet) in length, it must be able to withstand the flooding of any one compartment, treating the machinery space as a floodable compartment.
2. (b)When doing the calculations required in paragraph (a) of this section, the following permeabilities must be assumed:
   1. (1)0.95 in all locations except the machinery space.
   2. (2)0.85 in the machinery space.