---
kind: "section"
citation: "46 C.F.R. § 173.063"
title: "46"
number: "173.063"
heading: "Intact stability requirements."
url: "https://uscodex.org/cfr/46/173.063"
---

# §173.063. Intact stability requirements.

- (a) Except as provided in this section, each sailing school vessel must meet the intact stability requirements in §§ [170.170](/cfr/46/170.170.md), [171.050](/cfr/46/171.050.md), and [171.055](/cfr/46/171.055.md) of this chapter.
- (b) In applying the requirements in §§ [170.170](/cfr/46/170.170.md) and [171.050](/cfr/46/171.050.md) of this subchapter, the value of “T” is equal to the angle of heel at which the deck edge is immersed or 1/3 of the downflooding angle, whichever is less.
- (c) In applying the requirements of [§ 171.055(d)](/cfr/46/171.055.md?p=d) (1) and (2) of this subchapter—
  - (1) The value “X” is equal to 0.6 long tons/square foot (9.8 metric tons/square meter).
  - (2) For a vessel in service on protected or partially protected waters, values “Y” and “Z” are determined from graphs 173.063 (a) and (b) and multiplied by the multiplier in graph 173.063(e).
  - (3) For a vessel in service on exposed waters, “Y” and “Z” are determined from graphs 173.063 (c) and (d) and multiplied by the multiplier from graph 173.063(e).
  - (4) To convert required numerals to units of “metric tons/square meter,” multiply by 10.94.
- (d) Each vessel of the open boat type that is required to comply with the requirements in §§ [178.300](/cfr/46/178.300.md) and [178.310](/cfr/46/178.310.md) of this chapter, may instead comply with the requirements in [paragraph (e)](#e) of this section.
- (e) In lieu of complying with the requirements of [paragraph (b)](#b) of this section, an open boat may be provided with sufficient air tankage or other internal buoyancy to maintain the vessel afloat when the vessel is completely flooded or capsized. If foam is used to comply with this paragraph, it must be installed in accordance with the requirements in [§ 170.245](/cfr/46/170.245.md) of this subchapter.
- (f) A sailing school catamaran must meet the intact stability requirements in [§ 171.057](/cfr/46/171.057.md).

## Notes

### Amendments

[CGD 83-005, 51 FR 925, Jan. 9, 1986, as amended by CGD 85-080, 61 FR 946, Jan. 10, 1996]

### Authority

Authority: 43 U.S.C. 1333; 46 U.S.C. 2113, 3306, 5115; E.O. 12234, 45 FR 58801, 3 CFR, 1980 Comp., p. 277; DHS Delegation No. 00170.1, Revision No. 01.3.

### Source

Source: CGD 79-023, 48 FR 51045, Nov. 4, 1983, unless otherwise noted.

### Amendments

[CGD 83-005, 51 FR 925, Jan. 9, 1986, as amended by CGD 85-080, 61 FR 946, Jan. 10, 1996]