AB Unlimited requires 1080 days of deck service on Oceans or Great Lakes. AB Limited requires 540 days of deck service on vessels of 100 Gross Tons or more, not exclusive to rivers & smaller inland lakes of the U.S. AB Special requires 360 days of deck service on navigable waters of the U.S.

Able Seaman Special (AB Special) is used on most small ferry vessels, OSVs, and tugboats in the U.S. It is the most common AB rating for vessels that operate only on navigable waters within the U.S.

The rating must: Age: be not less than 18 years of age. Certification: Meet the requirements for certification as a rating forming part of a navigational watch. Seagoing Service: have completed 18 months approved seagoing service in the deck department, or 12 months and completed approved training.

For a 25, 50, or 100-Ton Master Near Coastal captain's license, 720 days of sea time are required with 360 outside the boundary line.

The USCG told us to expect an automated email within 18 business days (business days do not include weekends and public holidays) confirming receipt of your medical certificate application. If you don't receive confirmation within that time frame, the USCG recommends that you resend your medical application.

AB Special: To qualify for AB Special, you need 360 days of experience aboard a ship on the ocean or U.S. waters. AB OSV (Off-shore Supply Vessel): AB OSV requires six months of experience on an ocean or U.S. vessel.

To get your able seaman endorsement, you need documented sea service — at least 180 days. What qualifies as a day of sea service? ing to the U.S. Coast Guard, 8 hours of day-working or watchstanding, not including overtime. You can count sea service from age 16 onward.