46 CFR 169.230 - Underwater Survey in Lieu of Drydocking (UWILD).
(a) The Officer in Charge, Marine Inspection (OCMI), on a case-by-case basis, may approve an underwater survey instead of a drydock examination at alternating intervals if your vessel is -
(1) Less than 15 years of age;
(2) A steel or aluminum hulled vessel;
(3) Fitted with an effective hull protection system; and
(4) Listed in § 169.229(a)(1) or (2) of this part.
(b) For vessels less than 15 years of age, you must submit an application for an underwater survey to the OCMI at least 90 days before your vessel's next required drydock examination. The application must include -
(1) The procedure for carrying out the underwater survey;
(2) The time and place of the underwater survey;
(3) The method used to accurately determine the diver's or remotely operated vehicle's (ROV) location relative to the hull;
(4) The means for examining all through-hull fittings and appurtenances;
(5) The condition of the vessel, including the anticipated draft of the vessel at the time of survey;
(6) A description of the hull protection system; and
(7) The name and qualifications of any third party examiner.
(c) If your vessel is 15 years old or older, the cognizant District Commander, on a case-by-case basis, may approve an underwater survey instead of a drydock examination at alternating intervals. You must submit an application for an underwater survey to the OCMI at least 90 days before your vessel's next required drydock examination. You may be allowed this option if -
(1) The vessel is qualified under paragraphs (a)(2) through (4) of this section;
(2) Your application includes the information in paragraphs (b)(1) through (b)(7) of this section; and
(3) During the vessel's drydock examination, preceding the underwater survey, a complete set of hull gaugings was taken and they indicated that the vessel was free from appreciable hull deterioration.
(d) After the drydock examination required by paragraph (c)(3) of this section, the OCMI submits a recommendation for future underwater surveys, the results of the hull gauging, and the results of the Coast Guards' drydock examination results to the cognizant District Commander, for review.