GP Rating and DNS lead to different jobs, different ranks, and different lives at sea. Here's what separates them, explained from scratch, with no recommendation pushed either way.
If you've decided the merchant navy is for you, the next question is which door to walk through. For students finishing Class 12, two names come up again and again: GP Rating and DNS. They are not two versions of the same thing. They lead to different jobs, different ranks, and different lives at sea. Choosing between them is one of the most consequential early decisions you'll make, and it's worth understanding properly before a coaching centre makes it for you.
This article explains what each route actually is, what separates them, and the honest trade-offs of each. It does not tell you which to pick. That depends on your marks, your finances, and what you want your working life to look like — and only you can weigh those.
What is GP Rating?
GP stands for General Purpose. A GP Rating is a member of the ship's crew rather than one of its officers. The course is short — typically around six months of pre-sea training — and the entry bar is lower, with some courses accepting candidates after Class 10 and others after Class 12.
A rating is the person who keeps the ship physically running: maintenance, watch-keeping support, deck and engine work under the direction of officers. It is hands-on, practical work. The route gets you to sea quickly and at a relatively low training cost, which matters enormously to families who cannot fund years of expensive education up front.
What is DNS?
DNS stands for Diploma in Nautical Science. It is an officer-track course. A DNS graduate begins their sea career as a trainee deck cadet and works toward becoming a navigating officer — eventually, with years of sea time and a series of competency examinations, potentially the Captain of a ship.
DNS requires Class 12 with Physics, Chemistry, and Mathematics, usually with a respectable aggregate. The course is longer and more academic than GP Rating, and the total cost of becoming an officer this way is considerably higher. In return, it places you on the officer ladder from day one.
The core difference: rating versus officer
Everything else flows from this single distinction. GP Rating puts you in the crew. DNS puts you on the path to becoming an officer. On a ship, that line is real — it shapes your responsibilities, your pay band, your accommodation, and your authority.
It's important to be clear about one thing, because coaching centres sometimes blur it. A rating is not permanently stuck as a rating. There are pathways — additional sea time, examinations, and bridging courses — through which a rating can rise into the officer ranks over time. But it is a longer, harder climb than entering as an officer cadet, and it demands real persistence. DNS is the faster, more direct route to officer rank; GP Rating is the cheaper, quicker route to sea, with the officer door reachable later through effort.
The ranks on a ship
A merchant ship has two parallel chains of command: the deck department, which handles navigation, cargo operations, and the running of the ship; and the engine department, which runs the propulsion, power, and machinery. Each department has its own ladder of officer ranks and its own ladder of rating ranks.
The General Purpose Rating sits at the entry rung of both ladders — which is exactly what the name means: qualified to support both deck and engine work. From there, the ladders separate.
Deck department
Officers (top to bottom):
- Master (Captain)
- Chief Officer (also called Chief Mate)
- Second Officer
- Third Officer
- Deck Cadet — officer trainee, where DNS and B.Sc. Nautical Science graduates begin
Ratings (top to bottom):
- Bosun — heads the deck ratings, supervises the same work as OS and AB
- Able-Bodied Seaman (AB)
- Ordinary Seaman (OS)
- General Purpose Rating
Engine department
Officers (top to bottom):
- Chief Engineer
- Second Engineer
- Third Engineer
- Fourth Engineer
- Trainee Engine Cadet — officer trainee, where B.Tech Marine Engineering and Graduate Marine Engineering graduates begin
Ratings (top to bottom):
- Fitter — specialist skilled rating: welding, lathe work, fabrication (a different job from Motorman, not a supervisory version of it)
- Motorman
- Wiper or Oiler
- General Purpose Rating
Other officer roles
- Electro-Technical Officer (ETO) — specialist officer with certification in shipboard electrical and electronic systems, including automation. Reports to the Chief Engineer.
Specialised ranks tied to ship type
These don't appear on every ship — they exist where the cargo demands it:
- Gas carriers — Cargo Engineer or Gas Engineer (certified engineer for cargo systems); Reeferman (certified rating handling refrigeration, no engineer's licence)
- Oil and chemical tankers — Pump Man (handles cargo pumping systems)
- Heavy deck-work ships — Deck Fitter may exist as a separate role; on most ships the Fitter is primarily an engine rating but does deck fabrication work too
The names above follow standard international nomenclature. On Indian-flagged vessels some titles are adapted, but the structure is the same.
Where each course puts you
- DNS graduate → enters the deck officer ladder as a Deck Cadet, working toward Third Officer once examinations and sea time are complete
- GP Rating → enters at the bottom rung of either the deck or engine rating ladder
The two ladders do meet — a rating with enough sea time and the right examinations can cross over and begin climbing the officer ladder — but that crossover is the long route, not the default one.
Trade-offs, honestly
Consider GP Rating if you want to start earning at sea sooner, if the cost of an officer-track education is genuinely out of reach right now, or if you didn't take PCM at Class 12 and don't meet the DNS academic requirements. The shorter course and lower upfront cost are real advantages, not consolation prizes.
Consider DNS if you have the Class 12 PCM background, can fund the longer education, and want to begin on the officer track directly. The higher cost and longer study period buy you a head start toward senior rank that a rating has to earn the long way around.
Neither route is "better." A capable, determined GP Rating can build an excellent career. A DNS cadet who treats the head start casually can stall. What matters more than the entry door is what you do once you're through it.
Before you commit: verify the institute
Whichever route you lean toward, the single most expensive mistake is paying fees to an institute that isn't actually approved to run the course it's selling. Approval in India is granted at the course level, not just the institute level — an institute can be approved for one course and not another. A centre approved to run GP Rating may not be approved to run DNS, and advertising one while you enrol in the other is a known trap.
Before you pay anyone, confirm the exact course at the exact institute against official records. You can check approval status directly through our Verify tool, and compare what each route involves on the Course Finder. Spending twenty minutes verifying before you spend lakhs enrolling is the cheapest insurance you will ever buy in this career.
An institute can be approved for one course and not approved for another. Always verify the specific course approval before paying any fees.
- 1Verify the instituteCheck that the institute appears in the DGS-approved list.
- 2Verify the courseConfirm the specific course is approved at that institute.
- 3Check expiry and placementConfirm the approval has not lapsed and that the institute offers placement.
- 4Check RPSL if placement promisedIf the institute promises sea-time placement, verify their RPSL licence.