46 CFR §171.060

1. (a)Each of the following vessels must be shown by design calculations to comply with the requirements in §§ 171.065 through 171.068 for Type I subdivision:
   1. (1)Each vessel 100 gross tons or more on an international voyage: and
   2. (2)Each vessel 150 gross tons or more in ocean service.
2. (b)Each vessel not described in paragraph (a) of this section must be shown by design calculations to comply with the requirements in §§ 171.070 to 171.073 for Type II subdivision.
3. (c)Except as allowed in § 171.070(c), each vessel must have a collision bulkhead.
4. (d)Each double-ended ferry that is required by paragraph (c) of this section to have a collision bulkhead must also have a second collision bulkhead. One collision bulkhead must be located in each end of the vessel.