Hello there

Yes if you want to study in IIT then you have to qualify JEE advanced for or getting a seat to study naval architecture and if you qualified JEE advanced then you get the chance to study either from IIT Madras or IIT kharagpur who offers naval architecture which is a subdomain of mechanical engineering discipline.

Now coming only to do naval architecture then it's not necessary to give joint entrance examination as there are many universities who offers graduate as well as post graduate certificate in naval architecture and to acquire an Academy tag of naval architecture you can do bachelor's or master's in the same discipline.

You can also give the exams like IMU or CUSAT for naval architecture to study in some other universities besides IIT if you don't want to give joint entrance examination.

To know more about joint entrance examination advanced you can refer the link:

https://engineering.careers360.com/exams/jee-advanced

I hope it helps you!

Thank you!