OK it is good to have facts. But let's look at that statistic properly and see the skew within that statistic and apply it to the game.
Let's start with the obvious: you can't kill a sub unless you first find it. Is it any surprise that aircraft did half the at-sea sub kills when they can fly relatively very fast and patrol a large region of ocean and so find a lot more subs than destroyers? U-boats had to spend many hours each day at the surface to recharge their batteries. The aircraft really found mostly "surface targets" that just happened to look like submarines. Please don't laugh and allow me to make my point. Furthermore, I am not giving much credit to kills on submarines made while the U-boat was diving to escape but still visible from the air. On the other hand - without knowing of any statistic to support me - I suggest that there was probably not a single kill by an airplane of a WWII submarine when such sub was fully submerged. I am excluding the good number of subs that were spotted cruising submerged at about periscope depth when - on a sunny day and with not too choppy seas - the dark outline of a sub sometimes was visible as far as 30 feet down and it was most easy to bomb it. It is still a "near surface kill" of a submarine that really was not operating as to its true ability. But surprisingly it was operating exactly how all the submarines in our game seem to operate. (more on this later). To conclude the first point - if you even out the difficulty in targets - you will see that airplanes had limited effectiveness in killing submarines and could only kill subs when they were at or very near the surface. The fact that this is how half of the subs were killed does not make the aircraft more effective than the destroyer. It simply racked up more kills because it got all the easy targets. In fact the WWII airplane was totally ineffective for truely submerged subs, but destroyers had no problem doing gunnery practise on any surfaced subs they happened upon. So, are you going to define "effectiveness" by the number of actual kills or are you going to consider the skew in the statistic? I think when you transpose the discussion to the game, you need to consider the skew in deciding whether DDs or CVLs are the most effective sub killers.
It is like looking at two bullies in school. One is a real fighter and the other is just a bully that picks on every kid much smaller than himself and - by the end of the yerar - he's beat up on a lot of little kids. But he doesn't come close to the ability of the real fighter. Who is the most effective fighter?
The next major point is that the CAGs on the CVL really can not fly. They are stuck to the CVL inspite of their range because of map mechanics. If each sea zone were divided into 5 sections and we were to say that a destroyer can only detect a sub within the small section it is in BUT a CVL can detect a sub in the section it is in and all adjacent sections, THEN the CVL really would be realizing its greater range that the CAG is given and be able to find subs much better than the DD can. Finding subs easier than the DD, it would be able to kill more and so be more effective.
However, because the DD actually travels faster (and map mechanics that lock in the fact that either you are in the same sea zone with the sub or you are not) the DD really has a more effective range because it will reach the sea zone with sub in it a bit sooner than the CVL, thereby decreasing the chance that the sub has snuck away to the next sea zone and is then undetected. This is especially true when you consider how most subs in the game are found. Just like in WWII, they are mostly found by aircraft. But the aircraft in the game that compares to that is the Naval Bomber and not the "CAG that can't fly".
But having found the sub with a NAV (which really take a rather long time to sink any SS) the next usual operation is to mission the nearest DD or CVL to that sea zone and so kill it quickly (before the sub gets into another sea zone or worse - into a new sea region - and needs to be found all over again). THe faster moving DD has a definite edge over the CVL in catching the sub before the sub escapes. This is one more reason why the DD is more effective.
Finally we need to consider that any retreating SS will survive if it is not killed before the retreat route gets the sub to the next sea zone. As we don't know the direction of retreat, if we miss a quick kill it means start over by trying to find the darn thing again. So speed of kill is very important in the game. Kill speed is mostly determined by how big your ASW number is. As I showed above, evened out for ICs spent and production time requirted, DDs give considerably more "bang for the buck" than does a CVL.
As I see it, that makes the DD a much more effective sub hunter AND a more effective sub killer.
As regards the part of my quote thrown back to me (aircraft were poor sub killers) my statement stands. In spite of aircraft in WWII killing half of the at-sea subs the aircraft at that time could not kill a sub as well as any destroyer could. THe aircraft could find more subs but - like the little school bully - they were not as effective as destroyers because the only thing they could sink was extremely easy sub kills. In fact, it is arguable if a sub operating as a surface vessel really ranks as a "submarine kill". I certainly don't think so when the discussion is regarding "effectiveness" which is skewed if we only consider number of kills and do not look at degree of difficulty to make the kill.
Finally, to conclude that point where I said "more later". The subs in the game act a lot like the many surface targets sunk by aircraft in WWII and which just happened to look like subs. It seems the game subs can not submerge and are always at the surface. I say this because they are always found just as easily as any surface unit and NEVER have I had a DD of mine in the same sea zone as any enemy SS and not made contact. It is not right. Game subs should be able to hide in a sea zone together with enemy units trying to find them, and whether they are found or not should depend on some other parameters that simply appear to be missing from the game.
