---
kind: "section"
citation: "46 C.F.R. § 174.145"
title: "46"
number: "174.145"
heading: "Intact stability requirements."
url: "https://uscodex.org/cfr/46/174.145"
---

# §174.145. Intact stability requirements.

- (a) In each condition of loading and operation, each vessel must be shown by design calculations to meet the requirements of [paragraphs (b) through (e)](#b..e) of this section.
- (b) The area under each righting arm curve must be at least 16.9 foot-degrees (5.15 meter-degrees) up to the smallest of the following angles:
  - (1) **The angle of maximum righting arm.**
  - (2) **The downflooding angle.**
  - (3) 40 degrees.
- (c) The area under each righting arm curve must be at least 5.6 foot-degrees (1.72 meter-degrees) between the angles of 30 degrees and 40 degrees, or between 30 degrees and the downflooding angle if this angle is less than 40 degrees.
- (d) The maximum righting arm shall occur at a heel of at least 25 degrees.
- (e) The righting arm curve must be positive to at least 60 degrees.
- (f) For the purpose of this section, at each angle of heel, a vessel'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.**

## Notes

### 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.