46 C.F.R. § 45.121
Freeing port area: Changes for trunks and side coamings
If a vessel has a trunk and does not meet the requirements of § 45.61 or has continuous or substantially continuous hatchway side coamings between detached superstructures, the minimum area of the freeing port openings must be obtained from the following table:
| Breadth of hatchway or trunk in relation to the breadth of ship | Area of freeing ports in relation to the total area of the bulwarks (percent) |
|---|---|
| 40 percent or less | 20 |
| 75 percent or more | 10 |