[neilbyrne]

Joe,
I agree with your post. My intent was to heap praise on Ducimus while offering a few suggestions with supporting background and trying to find out what the sim/cfg values actually meant in the way of detection ranges. I hope he enjoys his time off; he has more than earned it.
The IJN’s ASW record was, to me, no better than mediocre. We lost 52 subs in the Pacific war, a couple of those not to IJN ASW efforts, but to bad torpedoes, grounding, etc. The IJN sank about 20% of the USN’s engaged force of submarines and killed one in seven US submariners. This was bad enough to make being a submariner the most dangerous thing an American could do in WWII. Second was being air crew in an 8th AF heavy bomber, one in ten died. In the infantry, the fatality rate was around 1%.
Contrast this to the Atlantic theater where the allies sank 785 German U-boats and killed five in six German submariners making that, so far as I know, the most dangerous thing anyone could do in WWII. Of the 785, US forces sank only 129. The British RN and what was the world’s third largest navy on VJ-day, the Royal Canadian Navy sank the rest. Clearly there were many reasons for the allied victory in the Atlantic. My two favorites are Ultra and the enormous allied ship building capability. Just two examples, in March ’42, the navy let a contract to Kaiser Steel to build fifty CASABLANCA Class CVEs and took possession of #50 a year later. We once built a Liberty ship as a war bond stunt in 96 hours from the keel to the whistle.
You are absolutely correct about the escort mission. The mission is to get your charges safely across the finish line. If submarines are coincidently sunk, that’s terrific, but the overriding mission is to be a good shepherd, get the sheep home. Once the allies had the escorts to accomplish this reliably, they went on the offensive and formed hunter killer groups (HUK) centered on CVEs. The HUK mission was to come to the aid of beleaguered convoys and when free of that, to hunt down and kill U-boats based on datums received from HF/DF and Ultra. The IJN never had the surplus CVEs or escorts to engage in this tactic.
The reason I classed the IJN’s ASW as mediocre was not that they didn’t have effective and well trained folks. They did. The problem was that their inter-war ship building program encumbered them with a force structure that was unsuited to what developed into a massive convoy escort ASW mission. This, by the way, was the exact same mistake that the USN and RN inter-war construction programs made, but the allies’ wartime shipbuilding programs were robust enough to bail them out of their errors.
The IJN’s escort shortage became so acute that it was noticeable in USN patrol reports toward the second half of ’44. SUBPAC jumped on this and changed the target priority list for, as I remember, one patrol cycle. Escorts were moved way up the food chain, only subordinate to capital ships (CV/BBs) and tankers. One result, USS HARDER torpedoed and sank three IJN escorts and crippled two others in less than a week in October ’44.