Use of radar in WW2 submarines

[Malcolm Lewis]

Interesting to read Commander Jeremy Nash RN’s obituary in the London Daily Telegraph 4th January. He served throughout WW2 in submarines. Specifically mentioned is the attack and sinking by his boat Proteus on November 10 1941 of the German troopship Ithaka off Greece in what is held to be the first attack by a submarine using radar.
Very early days for radar. This early set was known as SD radar I believe. Sets gradually improved but I am interested to learn how effective was radar for submarines during the hostilities considering it was situated so close to the surface of the sea, its short range and having to detect objects, particularly aircraft, approaching at high speed.
Did the Germans also have radar on their subs at that time?

[David Hepper]

The service history of Proteus may be found here:
https://uboat.net/allies/warships/ship/3403.html
and from the log extracts reproduced there, it appears that in the November 1941 attack she detected her target at just under four miles and later detected an aircraft at five miles, which gave her time to dive.

The SD radar was an American set, and according to Friedman [Naval Radar London 1981] was introduced during 1941. It had a simple dipole aerial and was expected to have a maximum range of 20nm on an aircraft at 10,000 feet in ideal conditions. However, Friedman states that in service the set proved ineffective against the threat of a low flying aircraft.

The US Navy supplemented then replaced the SD with the SJ set from 1942, and this was used to some effect by US submarines in the Pacific – see the piece from the Northern Mariner (Journal of the Canadian Nautical Research Society) vol.14 no.3 pp.27-40:
https://www.cnrs-scrn.org/northern_mariner/vol14/tnm_14_3_27-40.pdf

The German Navy developed a range of radars for U-Boats but were not produced in any large numbers. See https://uboat.net/technical/radar.htm for some detail

For the Royal Navy, they evidently obtained both SD and SJ sets (see photo of HMS Tiptoe with SJ radar: https://www.iwm.org.uk/collections/item/object/205188028 ) from the USA from 1941 onwards, although I do not think they were widely fitted.
For British radar, details may be found in Development of Radar Equipment for the Royal Navy (ed: F A Kingsley; Basingstoke 1995), which states that there were trial installations of submarine radar, but there were concerns at the poor capability of detecting low flying aircraft. A 1945 report is quoted, which stated that “…results showed that surface cover was satisfactory, but that the probability of detecting aircraft at ranges greater that 10,000 yards was very low”. A special, dual-frequency set for subs was developed (Type 267W) which first went to sea in HMS Tuna in August 1944

[Frank Scott]

SD was a long wave metric radar, whose range & bearing discrimination were both totally inadequate for a torpedo attack fire control solution. The later SJ set was 10 cm, which was much more accurate, so could be used for torpedo attacks. As I understand it, the initial detection here was by radar, but the submarine then closed for a conventional attack.

[Paul A]

I am currently reading an Amazon Kindle copy of the war reports of USS Dace, which includes many instances of it’s use and comparing it to SD.

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