Hey everyone,
I've done a couple of campaign starts in 1890, and it seems to me that building ships in anything like historical fashion seems to make no sense in the early periods.
Now this may simply be a result of the dreadnought design principle being superior, but especially if you start a campaign in 1890, secondary guns are completely useless. There seems to be absolutely no reason whatsoever to add them to a ship except to balance weight. At any range beyond 1km, you want the biggest gun you can get to have even a remote chance of hitting. At any distance under 1km, it's all about the torpedoes anyways.
Secondary guns don't defend against torpedo boats because the chance to hit them beyond torpedo range is so atrocious that their fire is simply irrelevant. Yes you might occaisonally sink a single torpedo boat, but you're still generally better off using your big guns against those since they are a huge threat.
Perhaps it would be better if torpedoes weren't as OP, but currently it seems to be the best strategy to just slap as many torpedoes on everything as you can and otherwise just add the biggest guns you can.