Fleet/Ship training is a cascade. To get the most effective use out of it, you want the officers in charge of your navy to have as high a skill in Crew Training Rating as possible.
So, if your Admiral commanding Fleet Headquarters doesn't have the skill, you may want to move him around, as he does affect the fleets under him.
Assuming you have a starting setup;
Fleet Headquarters - Admiral (needs the highest Crew Training you can get)
Battle Fleet (or whatever you call it)- The fleet Senior Officer (shows on the F12 tab for the fleet) should have the highest rating you can. This position goes to the highest ranking ship commander in the fleet by default.
Individual ship- The actual captain.
All of this adds up, so if your Admiral as a 125 rating, the Fleet commander has a 100 rating, and the ship captain has a 50 rating, the senior officers pass down some effect to the ship captain. If your admiral or fleet commander doesnt have any skill in Crew Training, it will take a long time for the ship captain to train up the ship. The flip side is that if the captain doesnt have the skill, but the admiral and fleet commander do, the ship will still increase.