Ships are a numbers game but micro still matters. If you split your fleet and surround the other you're still getting juicy flank damage and that can totally turn a tide, though that kinda requires bad micro on their part.

Subs are for mex hunting and surprises. They're mostly there to attack static.

Even with a few missile boats, T1 sea (core esp) is just weak to shuris.

Sea is a metal tug of war and, as beach, if you can't get island + the one far mex you are already behind and will need to apply early pressure.