---
kind: "section"
citation: "46 C.F.R. § 174.185"
title: "46"
number: "174.185"
heading: "Intact stability."
url: "https://uscodex.org/cfr/46/174.185"
---

# §174.185. Intact stability.

- (a) Each OSV must be shown by design calculations to meet, under each condition of loading and operation, the minimal requirements for metacentric height (GM) in [§ 170.170](/cfr/46/170.170.md) of this chapter, and in either [§ 170.173](/cfr/46/170.173.md) of this chapter or [paragraphs (b) through (e)](#b..e) of this section.
- (b) The area under each righting arm curve must be at least 0.08 meter-radians (15 foot-degrees) up to the smallest of the following angles:
  - (1) The angle of maximum righting arm;
  - (2) The downflooding angle; or
  - (3) 40 degrees.
- (c) The downflooding angle must not be less than 20 degrees.
- (d) The righting arm curve must be positive to at least 40 degrees.
- (e) The freeboard at the stern must be equal to the freeboard calculated to comply with subchapter E of this chapter or to the value taken from Table 174.185, whichever is less.
- (f) For paragraphs [(b)](#b) and [(d)](#d) of this section, at each angle of heel an OSV's righting arm may be calculated considering either—
  - (1) The vessel is permitted to trim free until the trimming moment is zero; or
  - (2) **The vessel does not trim as it heels.**
- (g) For the purpose of paragraphs [(b)](#b) and [(d)](#d) of this section, the method of calculating righting arms chosen must be the same for all calculations.

## Notes

### Source

Source: CGD 82-004 and CGD 86-074, 62 FR 49353, Sept. 19, 1997, unless otherwise noted.

### Authority

Authority: 42 U.S.C. 9118, 9119, 9153; 43 U.S.C. 1333; 46 U.S.C. 3306, 3703; E.O. 12234, 45 FR 58801, 3 CFR, 1980 Comp., p. 277; Department of Homeland Security Delegation No. 0170.1. Section 174.180 also issued under sec. 617, Pub. L. 111-281, 124 Stat. 2905.

### Source

Source: CGD 79-023, 48 FR 51048, Nov. 4, 1983, unless otherwise noted.