Also, it looks like you’ve made submarines 1 IPC cheaper and given them a convoy raiding ability, without any real compensating disadvantages. You’ve changed the submerge ability, but on balance I think the submerge ability is still equally powerful. I think submarines are already a pretty good buy OOB at 6 IPCs, in part because they are the cheapest ship and therefore often the best available fodder.
One thing to know about Subs A2first strike A1 C5 is that loosing them on defense as fodder, is a pretty good news to the attacker. Because, if they submerge, they will gets a much better attack factor than DDs, and for 5 IPCs, pretty cheap to buy. Also, you cannot use them as fodder against other sub.
So, on offence, it is better to lose DDs because A2 first strike should be preserved.
On defense, it is better to use your Sub later, hence Submerging eventually.
And Subs cannot hit subs so you must pick DD as fodder instead.
