46 CFR §172.133

1. (a)If a type I hull is required, design calculations must show that the vessel can survive damage at any location.
2. (b)Except as provided in § 153.7 of this chapter, if a type II hull is required, design calculations must show that a vessel—
   1. (1)Longer than 492 feet (150 meters) in length can survive damage at any location; and
   2. (2)Except as specified in paragraph (d) of this section, 492 feet (150 meters) or less in length can survive damage at any location.
3. (c)If a Type III hull is required, design calculations must show that a vessel—
   1. (1)Except as specified in paragraph (d) of this section, 410 feet (125 meters) in length or longer can survive damage at any location; and
   2. (2)Less than 410 feet (125 meters) in length can survive damage at any location except to an aft machinery space.
4. (d)A vessel described in paragraph (b)(2) or (c)(1) of this section need not be designed to survive damage to a main transverse watertight bulkhead bounding an aft machinery space. Except as provided in § 153.7 of this chapter, the machinery space must be calculated as a single floodable compartment.