46 CFR §174.055

1. (a)The wind heeling moment (Hm) of a unit in a given normal operating condition or severe storm condition is the sum of the individual wind heeling moments (H) calculated for each of the exposed surfaces on the unit; i.e., Hm=Σ H.
2. (b)Each wind heeling moment (H) must be calculated using the equation:
3. (c)When calculating “A” in the equation described in paragraph (b) of this section—
   1. (1)The projected area of each column or leg; if the unit has columns or legs, must not include shielding allowances;
   2. (2)Each area exposed as a result of heel must be included;
   3. (3)The projected area of a cluster of deck houses may be used instead of the projected area of each individual deck house in the cluster; and
   4. (4)The projected area of open truss work may be calculated by taking 30% of the projected areas of both the front and back sides of the open truss work rather than by determining the projected area of each structural member of the truss work.