Shortround6
Major General
Thank you for maps and the lists of the Air Fields. I hadn't realized the Japanese used a lot more short hops than long voyages.
I am guessing that most of the eastern shipping routes shown were supply routes for Japanese bases? Very little cargo going back to Japan unless the ships did a triangle (Japan to Truck/Rabaul then to west and then back to Japan?)
The Japanese escort/convoy saga is rather long and marked by several shifts (?).
It also needs looking at the opposition.
Japanese AS was, from a Japanese point of view, horribly ineffective based on results. According to one source (certainly subject to question) they got 173 Kaibokan into service, but many did not show up until late 1944 or 1945 which was too late. These ships only claimed 6 (?) of the 52 US subs lost during the war. Japanese destroyers may have claimed another 6 (?) doing escort duty and perhaps another 5 escorting Japanese war ships (?).
US Subs claimed 1113 merchant ships of 500 tons or more.
The Japanese had several AS warship classes being designed in the late 30s. So there was some interest. Prototype were built and modified designs were approved. Early designs were too expensive in hull construction (not simple enough).
First 4 out of 16 planned in 1937/38. 860 tons standard. In some ways a rather good escort ship with diesel engines for 19-20kts and very long range.
Three old 12cm destroyer guns offered fair firepower against surface raiders, Except the allies didn't use surface raiders very much, even against invading fleets.
The Japanese also kept mine sweeping on their escort ships for a long, long time. Sucking up space/weight that could have been used for AS or AA.
Like all Japanese ships the AA sucked. AS built they had two twin 25mm AA guns, the 12cm guns lacked elevation and/or fire control.
Sources vary as to wither these ships were designed for 12 or 16 or 18 depth charges or if there were any intermediate stages before they got to the 36 DC load in 1942.
But there were only 4 ships so the exact number of chargers just show thinking of the time in planning, not actual fighting capability. AS was actually 3rd on their list of priorities.
These class A escorts (Shimushu class) were also tasked with patrol and fishery protection around the Kurile Islands (they had insulation for cold weather for the crew) and they were fitted for minesweeping.
There were some 'sub-chasers' of anywhere from 170 tons to 290 tons pre-war (12 craft total) and the 438-420 ton CH 13 and CH 28 classes from 1939 on. These ended with the CH 89 (?) in 1944.
Other "escorts" were old WW I destroyers that we have already discussed.
The Etorofu (Type A imp) and Mikura Classes (Type B) were planned at about the same time but the Mikura's were not laid down until the end of 1942 (Mikura) and 1943 (7 more with last laid down Nov 1943).
Unfortunately the sensor fit was often late and behind the times. The first 3 Etorofu's were commissioned in March of 1943. As completed armament changed for initial design and they had the 60 DC charge load but this is late spring/summer of 1943. They were completed with Model 93 sonar and type 93 hydrophone while the the older Shimushu class had completed with hydrophones only and were refitted with sonar. Radar did begin to show up in escorts in the summer of 1943, which considering the state of Japanese radar in 1942/43 is OK but considering the threat from the American subs?
Hedgehog was on about 100 ships before it got it's first kill, Nov 1942. Japanese wound up with an Army single 8cm mortar for an ahead throwing weapon. British got their first kill with a Squid July 31st 1944. This is too late for the Japanese but the Japanese were very behind on AS warfare. As I said, this was somewhat masked by the American problems with their torpedoes which took until the summer of 1943 to fully solve.
According to one book on April 19th 1942 the Japanese had two escort groups. The 1st escort group and 10 old destroyers, two torpedo boats and 5 converted gun boats covering the Singapore-Japan route and the 2nd group had 4 old destroyers, two torpedo boats and in converted gun boat covering the Japan-Truk route/s.
Now in April 1942 the DEI sub fleet had been all but wiped out, there were a few(?) RN subs in Australia? and remnants of the US Asiatic sub fleet (Ex Philippines) was also scattered around trying to refit/repair/resupply in Australia and Pearl Harbor. US subs were trying to supply and/or withdraw US forces in the Philippines for much of the spring of 1942.
A coulda/shoulda scenario is what would the Japanese invasion of the Philippines/DEI/Singapore looked like IF the British had 12-15 boats in Singapore and IF Americans had working torpedoes and operated with same effectiveness that the Dutch navy did in Dec/Jan?
Japanese might have spent a lot more effort in 1942 on ASW.
I am guessing that most of the eastern shipping routes shown were supply routes for Japanese bases? Very little cargo going back to Japan unless the ships did a triangle (Japan to Truck/Rabaul then to west and then back to Japan?)
The Japanese escort/convoy saga is rather long and marked by several shifts (?).
It also needs looking at the opposition.
Japanese AS was, from a Japanese point of view, horribly ineffective based on results. According to one source (certainly subject to question) they got 173 Kaibokan into service, but many did not show up until late 1944 or 1945 which was too late. These ships only claimed 6 (?) of the 52 US subs lost during the war. Japanese destroyers may have claimed another 6 (?) doing escort duty and perhaps another 5 escorting Japanese war ships (?).
US Subs claimed 1113 merchant ships of 500 tons or more.
The Japanese had several AS warship classes being designed in the late 30s. So there was some interest. Prototype were built and modified designs were approved. Early designs were too expensive in hull construction (not simple enough).
First 4 out of 16 planned in 1937/38. 860 tons standard. In some ways a rather good escort ship with diesel engines for 19-20kts and very long range.
Three old 12cm destroyer guns offered fair firepower against surface raiders, Except the allies didn't use surface raiders very much, even against invading fleets.
The Japanese also kept mine sweeping on their escort ships for a long, long time. Sucking up space/weight that could have been used for AS or AA.
Like all Japanese ships the AA sucked. AS built they had two twin 25mm AA guns, the 12cm guns lacked elevation and/or fire control.
Sources vary as to wither these ships were designed for 12 or 16 or 18 depth charges or if there were any intermediate stages before they got to the 36 DC load in 1942.
But there were only 4 ships so the exact number of chargers just show thinking of the time in planning, not actual fighting capability. AS was actually 3rd on their list of priorities.
These class A escorts (Shimushu class) were also tasked with patrol and fishery protection around the Kurile Islands (they had insulation for cold weather for the crew) and they were fitted for minesweeping.
There were some 'sub-chasers' of anywhere from 170 tons to 290 tons pre-war (12 craft total) and the 438-420 ton CH 13 and CH 28 classes from 1939 on. These ended with the CH 89 (?) in 1944.
Other "escorts" were old WW I destroyers that we have already discussed.
The Etorofu (Type A imp) and Mikura Classes (Type B) were planned at about the same time but the Mikura's were not laid down until the end of 1942 (Mikura) and 1943 (7 more with last laid down Nov 1943).
Unfortunately the sensor fit was often late and behind the times. The first 3 Etorofu's were commissioned in March of 1943. As completed armament changed for initial design and they had the 60 DC charge load but this is late spring/summer of 1943. They were completed with Model 93 sonar and type 93 hydrophone while the the older Shimushu class had completed with hydrophones only and were refitted with sonar. Radar did begin to show up in escorts in the summer of 1943, which considering the state of Japanese radar in 1942/43 is OK but considering the threat from the American subs?
Hedgehog was on about 100 ships before it got it's first kill, Nov 1942. Japanese wound up with an Army single 8cm mortar for an ahead throwing weapon. British got their first kill with a Squid July 31st 1944. This is too late for the Japanese but the Japanese were very behind on AS warfare. As I said, this was somewhat masked by the American problems with their torpedoes which took until the summer of 1943 to fully solve.
According to one book on April 19th 1942 the Japanese had two escort groups. The 1st escort group and 10 old destroyers, two torpedo boats and 5 converted gun boats covering the Singapore-Japan route and the 2nd group had 4 old destroyers, two torpedo boats and in converted gun boat covering the Japan-Truk route/s.
Now in April 1942 the DEI sub fleet had been all but wiped out, there were a few(?) RN subs in Australia? and remnants of the US Asiatic sub fleet (Ex Philippines) was also scattered around trying to refit/repair/resupply in Australia and Pearl Harbor. US subs were trying to supply and/or withdraw US forces in the Philippines for much of the spring of 1942.
A coulda/shoulda scenario is what would the Japanese invasion of the Philippines/DEI/Singapore looked like IF the British had 12-15 boats in Singapore and IF Americans had working torpedoes and operated with same effectiveness that the Dutch navy did in Dec/Jan?
Japanese might have spent a lot more effort in 1942 on ASW.
