How can I join Merchant Navy after passing 10th class????

Merchant Navy can be joined after 10th as seafarer after qualifying pre sea courses

Age Limit
Age should be in between 16-25 Years

Medical Standards:
You should be physically and Mentally strong, fit for sea-services under standard norms

Eye-Sight:
6/6 without glasses,
No color Blindness

There are various courses to join after 10th in both private and govt training institute recognized and approved by Director General of Shipping, Ministry of Shipping. Theses are ;-

Pre Sea Training –
You will get proper training of maintenance of engine as well as deck.
You can join this course after 10th with minimum aggregate percentage of 40% with Mathematics, science and English as compulsory subject and should have 40% marks in each of them.
The time duration of this course is 06 months
Age limit is joining this course is 17 to 25 years.

Beside that other short term courses which enables you to join Merchant Navy are –

3 month Pre-Sea Course in Deck rating.
3 month Pre-Sea Course in Engine rating.
4 month Pre-Sea Course in Saloon rating.
Pre-sea Training for personnel, man Dredgers, Tugs, OSVs, etc on N.C.V (DECK)
Pre-sea Training for personnel, man Dredgers, Tugs, OSVs, etc on N.C.V (ENGINE)