Hello sir!

Merchant navy is one the best option for career.

You need to keep three things in mind and they are-

1. PCM needs to be the stream for 12th std.

2. Medical test will be taken and hence a good eye sight is very important.  The power should be below 2.5.

3. Third and last is the boat test. If you son is equally interested in the career then you should guide him. They are plenty of other options adter opting PCM.