(a) As permitted by §178.310(c) of this part, the following vessels may undergo the simplified stability proof test detailed in §178.330 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) of this part, a self-propelled pontoon vessel may undergo the pontoon simplified stability proof test detailed in §178.340 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 or §178.340 of this part, the authority issuing the stability letter may—

(1) Dispense with the requirements of the simplified stability proof test in §178.330 or §178.340 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 or §178.340 of this part, when necessary to adequately assess the vessel's stability.

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