Yea, I'm really looking forward to it. I'm gonna try to use it to grind through the entire USN line...
I hope you mean just grinding the captain for retraining.
If you actually try to grind the ships themselves, you'll be spending a lot of money to convert XP.
If you grind the captain when you AREN'T retraining, every game you play is a game not grinding new ships. (unless again, you're spending money to convert XP. Just to give an example, converting XP to go from a Tier 5 ship to a Tier 6 will cost you about 1400 doubloons.
The other issue is, if you're using the Sims to grind a US BB captain, you're playing a DD using a BB skill set. So you won't have Last Stand, the skill that gives more HP, or anything to do with torpedoes, for starters.