How much time do you have as Second Engineer?
There is no requirement in the rules for the time as an officer to have been licensed by the USCG.
46 CFR §11.510
(a) The minimum service required to qualify an applicant for endorsement as chief engineer of steam, motor, and/or gas turbine-propelled vessels is—
(1) One year of service as first assistant engineer; or
(2) One year of service while holding a license or MMC endorsement as first assistant engineer. A minimum of 6 months of this service must have been as first assistant engineer, and the remainder must be as assistant engineer. Service as an assistant engineer other than first assistant engineer is accepted on a two-for-one basis to a maximum of 6 months (2 days of service as a second or third assistant engineer equals 1 day of creditable service).