AB Limited (Able Seafarer–Limited) is the 18-month category of the Able Seaman deck rating, earned on larger vessels not confined to inland waters. It sits the same national AB written exam as every other AB category.
18 months of deck service on vessels of 100 GRT or more not exclusively confined to rivers and smaller inland lakes (46 CFR 12.403).
$280 in Coast Guard fees — $95 evaluation + $140 exam + $45 issuance, plus the CG-719K medical, drug test, and TWIC.
AB Limited is earned with 18 months of deck service on vessels of 100 GRT or more that are not exclusively confined to rivers and smaller inland lakes. The 100-GRT tonnage floor and the away-from-inland route requirement are what separate Limited from Special. It sits between Special (12 months) and Unlimited (36 months); because all AB categories share one written exam, the category can be raised later on sea time alone.
There is one national AB written exam for every category, so AB Limited sits the same test as AB Special, Limited, and Unlimited: two modules of 50 questions each at a 70% pass mark. The Rules of the Road module is closed-book.
Q450 · 50 Q · 70%
Q451 · 50 Q · 70%
Full detail, the six categories, and the Lifeboatman + marlinespike demonstrations are on the Able Seaman hub.
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AB Limited requires 18 months of deck service on vessels of 100 GRT or more that are not exclusively confined to rivers and smaller inland lakes, whereas AB Special requires 12 months with no tonnage floor. Both take the identical AB written exam (46 CFR 12.403).
No. There is one national AB written exam — Q450 plus Q451 — for every category including Limited and Unlimited. The categories differ only in the required sea service and the scope of the issued endorsement.
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