46 CFR 71.50-25 - Alternative Hull Examination (AHE) procedure.
(a) To complete the underwater survey you must -
(1) Perform a general examination of the underwater hull plating and a detailed examination of all hull welds, propellers, tailshafts, rudders, and other hull appurtenances;
(2) Examine all sea chests;
(3) Remove and inspect all sea valves in the presence of a marine inspector once every five years;
(4) Remove all passengers from the vessel when the sea valves are being examined, if required by the Officer in Charge, Marine Inspection (OCMI);
(5) Allow access to all internal areas of the hull for examination, except internal tanks that carry fuel, sewage, or potable water. Internal tanks that carry fuel must be examined in accordance with § 71.53-1 of this part. Internal sewage and potable water tanks may be examined visually or by non-destructive testing to the satisfaction of the attending marine inspector; and
(6) Meet the requirements in § 71.50-27 of this part.
(b) A marine inspector may examine any other areas deemed necessary by the OCMI.
(c) If the AHE reveals significant deterioration or damage to the vessel's hull plating or structural members, the OCMI must be immediately notified. The OCMI may require the vessel be drydocked or otherwise taken out of service to further assess the extent of damage or to effect permanent repairs if the assessment or repairs cannot be completed to the satisfaction of the OCMI while the vessel is waterborne.