The closest the CPs got to winning the war was the U-Boat’s attempt to starve Britain into surrender.
It looks like there are no convoy zones, so how could they achieve this in the game?
With American entry delayed at least for a few turns, and presumably effective American forces delayed further, what incentive is there for Germany to bother with a surface fleet?
This is especially so if (as seems certain) ships spend all their time at sea and are unlikely to last long if they’re seen as any particular threat.
My thinking for solving these issues (not going to happen I know):
Ships in port - allows ships to remain in dock and be safe from attack by sea. Really, without this how long is the Austrian Navy going to last?
Convoys: I was never entirely convinced by the A&A convoy system, and am thinking of ways of reworking it.
In particular - combine convoying with armaments/supply rules.
Before declaring war, America traded with all major powers, including war materials. This was most important in supplying shells and ammunition. I’ve suggested elsewhere that all units (or perhaps just artillery) expend shells when they fire, and that these items must be supplied to the armies in the field, being transported from factories. Armies on the western front regularly ran out of shells, and importing from America was one solution to this.
So make shells the commodity imported via convoy zones (by both sides), with it being most unlikely that either side can produce enough to keep artillery continually supplied (shells should be cheap enough, but still count against factory capacities) without imports. This might also give Germany enough incentive to declare unrestricted sinking on the basis that depriving the Western Allies of ammunition is worth the risk of bringing America in earlier.
http://www.youtube.com/watch?v=x_FAOk4uMp8
PS probably 3 types of shell: HE/Shrapnel, Gas, and Smoke