Hey there

Your question is incomplete as you have not mentioned the name of organization in which you are asking for joining. However after completing diploma in nautical  science you can get admission in various companies like:

• Northern Marine management India private limited
• ABG shipyard
• American cruise lines
• SAIL
• Ocean shipping Service private limited
• ONGC
• ESSAR shipment
• Carnival cruise line

For more:

https://www.google.com/url?sa=t&source=web&rct=j&url=https://www.careers360.com/courses/nautical-science-course&ved=2ahUKEwjEv-3s9O_zAhWOzzgGHWZeBF8QFnoECA0QAQ&usg=AOvVaw2ul7WZIut4F7hT2j8KIyUg