ORIGINAL: PresterJohn
non sequitor the presence of sunk ships that could have been used as escorts doesn't demostrate that they were used as escorts, they had multiple roles. I am also not arguing that the Japanese never escorted convoys, i believe that military ones did get escorted.
This discussion is basically about the inability of the allies to reproduce the historic mauling of the Japanese merchant fleet. There are a number of possibilities as to why this happens, the modelling of the Japanese ASW weapon systems is one. I think that far more important is the use of convoys by Japanese players and the effective use of ASW assets (air and sea). Also other player actions such as convoy routing. I know by adjusting convoy routes i dramatically reduce sub attacks.
In the first year of the pbem game i am in i did have poor merchant routing and convoys. Very large number of attacks, several a day, i wa only really saved by the allied duds. I learned and now i aggresively search for and prosecute allied subs with air and naval units. Seems to work. Japanese didn't seem to do that IRL. Ive not reached '44 yet but mid '43 and allied subs are not a huge problem. Don't think ive got the "killer" E's yet either.
I edited in a link to an archive of patrol reports. Read some. You will see that I am correct and you are not.
There are several issues involved in this thread. One is the results achieved against the Japanese merchant fleet. Those may or not be historic depending on a myriad of factors. Submarines are prevented in the code from attacking multiple targets in the same formation in the same attack. This was common in RL. There are also device-line constraints where more, or fewer, torpedoes are expended in the game than would have been the case in RL. Balanced against these factors are a very high op tempo in the game due to lack of crew fatigue as a factor, unrealsitic speed of major repairs, and the lack of a required R&R and refit period even for undamaged boats.
The effectiveness of specific ASW platforms is parallel to these issues. I don't believe there is any dispute that some IJN assets, in particular the E classes, are over-powered against history. JWE spoke at length why this is the case, and unlike you or me he has seen the exec file code, or has conferenced with Dan B. and others who have seen it. If he says there's an issue I believe him. His Da Babes team went to some lengths to address these factors in data, which is probably the only way to go for us other players.
To your other points, I agree there are ways for the Japanese player to use some of the above game features to "game" results. In particular, the one-shot, one-target code base allows fewer than historic merchants to be sunk in a PBEM game if very large, ahistoric convoys are formed. I don't know if there are artificial limits built in to the game to motivate speed of turn resolution, but I don't think I've ever, in years of aggressive submarine play, seen more than five submarine attacks in a turn, and that's not historic, or statistically likely either. I'll never know unless a dev reveals the code, but I suspect there are governors on attack volumes inserted as a game-balancing device in concert with the very high op tempo and single-attack mechanisms.
As for routing, there are only so many ways to get things to the HI, the choke points are where they were historically, and, while I somewhat disagree with the degree of penalty imposed on subs by shallow water, in general if good choke point patrol areas are managed I don't think routing need be a big penalty to the Allied player. That said, I also suspect that few Allied PBEM players want to exert the time needed to really manage their subs to historic levels. Far more players here seem to groove on the air war than the submarine campaign. Perhaps some day I'll play a PBEM game and see if I'm wrong.