46 CFR §171.085

1. (a)Paragraphs (b) through (g) of this section apply to each vessel of 100 gross tons or more and paragraphs (h) through (j) of this section apply to each vessel that is less than 100 gross tons.
2. (b)The portion of the collision bulkhead that is below the bulkhead deck must be watertight.
3. (c)Each portion of the collision bulkhead must be at least—
   1. (1)5 percent of the LBP from the forward perpendicular in a motor vessel; and
   2. (2)5 feet (1.52 meters) from the forward perpendicular in a steam vessel.
4. (d)The collision bulkhead must be no more than 10 feet (3 meters) plus 5 percent of the LBP from the forward perpendicular.
5. (e)The collision bulkhead must extend to the deck above the bulkhead deck if the vessel—
   1. (1)Is in ocean service; and
   2. (2)Has a superstructure that extends from a point forward of the collision bulkhead to a point at least 15 percent of the LBP aft of the collision bulkhead.
6. (f)The collision bulkhead required by paragraph (e) of this section must have the following characteristics:
   1. (1)The portion of the collision bulkhead above the bulkhead deck must be weathertight.
   2. (2)If the portion of the collision bulkhead above the bulkhead deck is not located directly above the collision bulkhead below the bulkhead deck, then the bulkhead deck between must be weathertight.
7. (g)Each opening in the collision bulkhead must—
   1. (1)Be located above the bulkhead deck; and
   2. (2)Have a watertight closure.
8. (h)Each collision bulkhead—
   1. (1)Must extend to the deck above the bulkhead deck if in ocean service as defined in § 170.050(f) of this chapter or to the bulkhead deck if in service on other waters;
   2. (2)May not have watertight doors in it; and
   3. (3)May have penetrations and openings that—
      1. (i)Are located as high and as far inboard as practicable; and
      2. (ii)Except as provided in paragraph (i) of this section, have means to make them watertight.
9. (i)Each vessel that is not required to comply with a one or two compartment standard of flooding may have an opening that cannot be made watertight in the collision bulkhead below the bulkhead deck if—
   1. (1)The lowest edge of the opening is not more than 12 inches (30.5 centimeters) below the bulkhead deck; and
   2. (2)There are at least 36 inches (92 centimeters) of intact collision bulkhead below the lower edge of the opening.
10. (j)Each portion of the collision bulkhead must be—
    1. (1)At least 5 percent of the LBP from the forward perpendicular; and
    2. (2)No more than 15 percent of the LBP from the forward perpendicular if the space forward of the collision bulkhead is not subject to damage stability requirements and at any location aft of the location described in paragraph (j)(1) of this section if the space forward of the collision bulkhead is subject to damage stability requirements.