ETO TO CLASS 3 MARINE ENGINEER

Hello Sir,
         At present i am trainee electrical officer. I wanted to know that can i switch from electro technical officer to class 3 marine engineer. If yes, than please give me information about the whole procedure and also i have TAR book which is provided by the company(Great eastern),Is this TAR book is valid for Marine engineer.And also teel me the sailing experience...
MERCHANT NAVY FORUM