---
kind: "section"
citation: "46 C.F.R. § 42.20-10"
title: "46"
number: "42.20-10"
heading: "Free surface."
url: "https://uscodex.org/cfr/46/42.20-10"
---

# §42.20-10. Free surface.


When doing the calculations required in §§ [42.20-6(a)](/cfr/46/42.20-6.md?p=a), [42.20-7(a)](/cfr/46/42.20-7.md?p=a) and [42.20-8(a)](/cfr/46/42.20-8.md?p=a), the effect of free surface of the following liquids must be included:

- (a) For each type of consumable liquid, the maximum free surface of at least one transverse pair of tanks or a single centerline tank must be included. The tank or combination of tanks must be that resulting in the greatest free surface effect.
- (b) For cargo liquids, unless the compartment is assumed to be empty as required by [§ 42.20-9(b)(3)](/cfr/46/42.20-9.md?p=b-3), the free surface of those compartments containing liquids is calculated at an angle of heel of not more than 5 degrees.

## Notes

### Amendments

[CGD 79-153, 48 FR 38649, Aug. 25, 1983]

### Authority

Authority: 46 U.S.C. 5101-5116; Department of Homeland Security Delegation No. 00170.1, Revision No. 01.4; section 42.01-5 also issued under the authority of 44 U.S.C. 3507.

### Amendments

[CGD 79-153, 48 FR 38649, Aug. 25, 1983]