(a) For the purpose of this subpart the following terms have the same definitions as given in subchapter IA of this chapter:

(1) Column stabilized unit.

(2) Mobile offshore drilling unit.

(3) Self-elevating unit.

(4) Surface type unit.

(b) For the purpose of this subpart—

(1) Downflooding means the entry of seawater through any opening that cannot be rapidly closed watertight, into the hull, superstructure, or columns of an undamaged unit due to heel, trim, or submergence of the unit.

(2) Downflooding angle means the static angle from the intersection of the unit's centerline and waterline in calm water to the first opening through which downflooding can occur when subjected to a wind heeling moment (Hm) calculated in accordance with § 174.055.

(3) Normal operating condition means a condition of a unit when loaded or arranged for drilling, field transit, or ocean transit.

(4) Severe storm condition means a condition of a unit when loaded or arranged to withstand the passage of a severe storm.