StacksVerified U.S. regulatory reference

46 CFR §171.067

Verified against eCFR.gov as of June 20, 2026View official text on eCFR.gov ↗
  1. (a)For the purpose of this section—
    1. (1)The main transverse watertight bulkhead immediately forward of a stepped bulkhead is referred to as bulkhead 1; and
    2. (2)The main transverse watertight bulkhead immediately aft of the stepped bulkhead is referred to as bulkhead 3.
  2. (b)If a main transverse watertight bulkhead is stepped, it and bulkheads 1 and 3 must meet one of the following conditions:
    1. (1)The separation between bulkheads 1 and 3 must not exceed the following:
      1. (i)If the factor of subdivision (FS) determined from § 171.065 (a) or (b) is greater than 0.9, the distance between bulkheads 1 and 3 must not exceed the maximum separation calculated to demonstrate compliance with § 171.065.
      2. (ii)If the factor of subdivision is 0.9 or less, the distance between bulkheads 1 and 3 must not exceed 90% of the floodable length or twice the maximum bulkhead separation calculated to demonstrate compliance with § 171.065, whichever is smaller.
    2. (2)Additional watertight bulkheads must be located as shown in Figure 171.067(a) so that distances A, B, C, and D, illustrated in Figure 171.067(a), satisfy the following:
      1. (i)Distances A and B must not exceed the maximum spacing allowed by § 171.065.
      2. (ii)Distances C and D must not be less than the minimum separation prescribed by § 171.065(e).
    3. (3)The distance A, illustrated in Figure 171.067(b), must not exceed the maximum length determined in § 171.065 corresponding to a margin line taken 3 inches (7.6 cm) below the step.
  3. (c)A main transverse bulkhead may not be recessed unless all parts of the recess are inboard from the shell of the vessel a distance A as illustrated in Figure 171.067(c).
  4. (d)Any part of a recess that lies outside the limits defined in paragraph (c) of this section must be treated as a step in accordance with paragraph (b) of this section.
  5. (e)The distance between a main transverse watertight bulkhead and the transverse plane passing through the nearest portion of a recessed bulkhead must be greater than the minimum separation specified by § 171.065(e).
  6. (f)If a main transverse bulkhead is stepped or recessed, equivalent plane bulkheads must be used in the calculations required to demonstrate compliance with § 171.065.