Hi does the US Navy have their own certified trainer instead of Gunny?

I was in the Navy. It really depends on what you are going to to do on the submarine. Unless you are a Gunny you probably will not have a GM train you. You are more then likely going to have someone who is the same rate as you train you in what you are doing on the sub. And Jake actually a Gunny in the Navy is a Gunners Mate which is a job! We always called our GM, Gunny. Never heard of "Guns" although I am sure there are some who do go by that.