---
kind: "section"
citation: "46 C.F.R. § 178.320"
title: "46"
number: "178.320"
heading: "Intact stability requirements—non-sailing vessels."
url: "https://uscodex.org/cfr/46/178.320"
---

# §178.320. Intact stability requirements—non-sailing vessels.

- (a) As permitted by [§ 178.310(c)](/cfr/46/178.310.md?p=c) of this part, the following vessels may undergo the simplified stability proof test detailed in [§ 178.330](/cfr/46/178.330.md) of this part, in the presence of a Coast Guard marine inspector, if they do not have tumblehome at the deck, measured amidships, that exceeds 2 percent of the beam:
  - (1) Monohull vessels; and
  - (2) **Flush deck catamaran vessels which are not pontoon vessels and carry not more than 49 passengers.**
- (b) As permitted by [§ 178.310(c)](/cfr/46/178.310.md?p=c) of this part, a self-propelled pontoon vessel may undergo the pontoon simplified stability proof test detailed in [§ 178.340](/cfr/46/178.340.md) of this part, in the presence of a Coast Guard marine inspector, if it satisfies all of the following requirements:
  - (1) The vessel carries not more than 49 passengers and does not make international voyages;
  - (2) The vessel operates on Protected Waters only;
  - (3) The vessel is constructed with only one deck;
  - (4) The buoyant hull volume consists of two symmetric, fully enclosed hulls;
  - (5) The cross section of each hull is circular or of wall-sided construction without tumblehome, and constant for at least 90 percent of the length of the hull;
  - (6) The hulls contain no machinery or tanks;
  - (7) **The portion of the deck accessible to passengers does not extend beyond—**
    - (i) The outboard edge of the hulls, and
    - (ii) The forward or the aft end of the hulls;
  - (8) There is no deck more than 0.15 meters (6 inches) above any point on any of the buoyant hulls;
  - (9) The distance between the centerlines of the hulls is not less than 1.83 meters (6 feet); and
  - (10) Each hull has a beam or diameter, as applicable, of not less than 0.61 meters (2 feet).
- (c) For a vessel that carries not more than 49 passengers, carries no deck cargo, and is otherwise eligible to undergo the simplified stability proof test detailed in [§ 178.330](/cfr/46/178.330.md) or [§ 178.340](/cfr/46/178.340.md) of this part, the authority issuing the stability letter may—
  - (1) Dispense with the requirements of the simplified stability proof test in [§ 178.330](/cfr/46/178.330.md) or [§ 178.340](/cfr/46/178.340.md) of this part when the vessel's stability can be adequately assessed by alternate means giving due consideration to each item that impacts a vessel's stability characteristics which include, but are not limited to, the form, arrangement, construction, number of decks, route, and operating restrictions of the vessel; or
  - (2) Authorize a change in the requirements of the simplified stability proof test in either [§ 178.330](/cfr/46/178.330.md) or [§ 178.340](/cfr/46/178.340.md) of this part, when necessary to adequately assess the vessel's stability.

## Notes

### Amendments

[USCG-2007-0030, 75 FR 78088, Dec. 14, 2010]

### Authority

Authority: 43 U.S.C. 1333; 46 U.S.C. 2103, 3306, 3703; E.O. 12234, 45 FR 58801, 3 CFR, 1980 Comp., p. 277; DHS Delegation No. 00170.1, Revision No. 01.3.

### Source

Source: CGD 85-080, 61 FR 966, Jan. 10, 1996, unless otherwise noted.

### Amendments

[USCG-2007-0030, 75 FR 78088, Dec. 14, 2010]