The Coast Guard is proposing to revise its merchant mariner credentialing regulations to implement the requirements of section 809 of the Coast Guard Authorization Act of 2010, Public Law 111-281. Section 809 eliminates the requirement for certain mariner populations to hold a Transportation Worker Identification Credential (TWIC).  This rule would propose revisions to Coast Guard regulations to reflect that certain mariner populations are exempt from the TWIC requirement and its associated fees.  Such mariners would still be required to apply for and obtain a Merchant Mariner Credential (MMC).  This rulemaking implements section 809 through revised regulations addressing the applicability of the TWIC requirements and the process of obtaining an MMC for affected mariners, and will supersede Coast Guard Policy Letter 11-15 issued December 2011, which provided affected mariners some of the relief presented by section 809 while the Coast Guard worked on this rulemaking.