(a) Vessels are exempt from 172.015 on voyages between:

1. (1) United States ports along the East Coast as far south as Cape Henry, VA;
2. (2) Wilmington, NC and Miami, FL;
3. (3) United States ports in the Gulf of America;
4. (4) Puget Sound ports and Canadian west coast ports or Columbia River ports, or both;
5. (5) San Francisco, Los Angeles, and San Diego, CA.

(b) Vessels exempt by paragraph (a) of this section must comply with the following conditions:

1. (1) The master is satisfied that the vessel's longitudinal strength is not impaired.
2. (2) The master ascertains the weather to be encountered on the voyage.
3. (3) Potential heeling moments are reduced to a minimum by carrying as few slack holds as possible.
4. (4) Each slack surface must be leveled.

5. (5) The transverse metacentric height (GM), in meters, of the vessel throughout the voyage, after correction for liquid free surface, has been shown by stability calculations to be in excess of the required GM (GMR), in meters.

   1. (i) The GMR is the sum of the increments of GM (GMI) multiplied by the correction factor, f and r.

      Where: r = (available freeboard) (beam) of the vessel and f = 1 if r is >0.268 or f = (0.268 r) if r is <0.268.

   2. (ii) The GMI for each compartment which has a slack surface of grain, i.e., is not trimmed full, is calculated by the following formula:

      GMI = (B3 × L × 0.0661)(Disp. × SF))

      where: B = breadth of slack grain surface (m L = Length of compartment (m) Disp. = Displacement of vessel (tons) SF = Stowage factor of grain in compartment (cubic meters/tons)