Vessel stability — metacentric height, free surface

46 CFR §178.210

Stability information. (a) Stability information (stability details indicated on the Certificate of Inspection, a stability letter, or a stability booklet), is required on certain vessels by paragraphs (b), (c), or (d) of this section. Enough stability information, including stability calculations and assumptions made to use them, must be provided to allow the master to be able to determine operating guidelines, loading restrictions, and ensure compliance with the applicable intact and damage stability regulations of this chapter. (b) A vessel which, under § 178.310 of this part, complies with requirements in subchapter S of this chapter, must have stability details on the vessel's Certificate of Inspection, a stability letter issued by the cognizant Officer in Charge, Marine Inspection …

46 CFR §178.230

Stability letter or Certificate of Inspection stability details. (a) When the cognizant OCMI or the Commanding Officer, Marine Safety Center determines, in accordance with § 178.210, that a vessel must have stability details indicated on its Certificate of Inspection or a stability letter, the owner or operator must submit the information listed in paragraph (b) of this section: (1) If § 178.210(c) is applicable, to the OCMI for approval; or (2) If § 178.210(b) is applicable, to the Commanding Officer, Marine Safety Center for approval. (b) If § 178.210(b) of this part applies, the applicable information described in subpart C of part 170 of this title, and the calculations used to determine that information, must be submitted in addition to the applicable information listed in paragra…

46 CFR §178.330

Simplified stability proof test (SST). (a) A vessel must be in the condition specified in this paragraph when a simplified stability proof test is performed. (1) The construction of the vessel is complete in all respects. (2) Ballast, if necessary, is in compliance with § 178.510 of this part and is on board and in place. (3) Each fuel and water tank is approximately three-quarters full. Any sewage tank should be either empty or full. (4) A weight equal to the total weight of all passengers, crew, and variable loads permitted on the vessel is on board and distributed so as to provide normal operating trim and to simulate the vertical center of gravity, causing the least stable condition that is likely to occur in service. The assumed weight per person of passengers and crew must be re…

46 CFR §28.501

Substantial alterations. (a) Except as provided in paragraph (b) of this section, a vessel that is substantially altered, including the cumulative effects of all alterations, need not comply with the remainder of this subpart, provided that it has stability instructions developed by a qualified individual which comply with § 28.530 (c) through (e). (b) A vessel that is substantially altered in a manner which adversely affects its stability, including the cumulative effects of all alterations, need not comply with the remainder of this subpart, provided the stability instructions required by paragraph (a) of this section are based on loading conditions or operating restrictions, or both, which compensate for the adverse affects of the alterations. (c) The following changes to a vessel's …

46 CFR §28.540

Free surface. (a) When doing the stability calculations required by this subpart, the virtual rise in the vessel's vertical center of gravity due to liquids in tanks must be considered by calculating the following— (1) For each type of consumable liquid, the maximum free surface effect of a tank, or a transverse pair of tanks, having the greatest free surface effect, in addition to a correction for service tanks; and (2) The free surface effect of each partially filled tank and hold containing a liquid that is not a consumable or containing fish or a fish product that can shift as the vessel heels. This should include correction for any loose water within the vessel's hull associated with the processing of fish. (b) The free surface effect of tanks fitted with cross connection piping m…

46 CFR §28.545

Intact stability when using lifting gear. (a) Each vessel which lifts a weight over the side, or that uses fishing gear that can impose an overturning moment on the vessel, such as trawls and seines, must meet the requirements of this section if that maximum heeling moment exceeds 0.67(W)(GM)(F/B), in foot-long tons (meter-metric tons), where: W = displacement of the vessel with the lifted weight or the force on the fishing gear included, in long tons (metric tons); GM = metacentric height with the lifted weight or force on the fishing gear included, in feet (meters); F = freeboard to the lowest weather deck, measured at amidships in feet (meters); and B = maximum beam, in feet (meters). (b) Except as provided in paragraph (f) of this section, each vessel must meet the requirements o…