Revised Table A (ver 4) of Diesels for Japanese Submarines - includes Snorting Output

Anonymous has kindly provided a review, Table A (ver 4), of the earlier Table A (ver 3) (provided February 5, 2018 at Submarine Matters)). 

At Table A (ver 4) (below) Anonymous introduces the primary sources of information on modern Japanese submarines [6]. Anonymous has revised the mechanical and electrical output figures, based on [6]. The importance of electrical ouput when snorting/snorkeling is briefly discussed and rough estimates are added using foregin data.

[Pete Comment: The whole Table and Footnotes appear to constitute a uniquely comprehensive source of information, unavailable elsewhere on the English language Internet. Below there is a small amount of further translation into English by Pete.]

The Revised Figures are expressed in blue color.

Table A (ver 4)

Class	First completion year	No. of subs	Model [1] or [2]	No. of diesels	No. of cylinders	Bore mm	Stroke mm	Mechanical ouput  surfaced kW	Electrical outpout  surfaced    kW [3]	Electrical output  snorting kW  [10]	Speed rpm
Oyashio .I	1960	1	V8V22/30mAL  [1]	2	16	220	300	993 [6]	794	-	850
Oshio	1964	5	V8V24/30mMAL [1]	2	16	240	300	1066 [6]	853	-	850
Uzushio	1970	7	V8V24/30AMT [1]	2	16	240	300	1287 [6]	1030	-	850
Yushio	1970	10	V8V24/30AMT [1]	2	16	240	300	1545 [6]	1236	-	850
Harushio	1990	7	12V25/25S [2]	2	12	250	250	2280 [6,8,9] (2500)	1824 (2000)	-	1200
Oyashio .II	1998	11	12V25/25S [2]	2	12	250	250	2500 [6,9]	2000	>=1800	1200
Soryu MK I & II [7]	2009	11	12V25/25SB [2]	2	12	250	250	2500	2000 [11]	>=1800	1200
29SS	-	-	12V25/31S [2] [4]	2	12	250	310	3100	2500 [11]	>=2250	1200

[1] KAWASAKI (under the license of MAN): V8V22/30mAL, V8V24/30mMAL, V8V24/30AMT

[2] KAWASAKI: 12V25/25S, 12V25/25SB, 12V25/31S

[3] Electical output = mechanical output x 0.8

[4] Estimated values:

[5] “Historical Development of Four Stroke Diesel Engine” by Kazuya Sato, Center of the History of Japanese Industrial Technology, National Museum of Nature and Science. This is comprehensive review. Representative diesel manufacturers in Japan (KHI, MHI, MAN-Japan, JFE, Mitsui, etc) reviewed that article.

[6] “History of Japan Maritime Defense Force Submarine” by Dr Yoichi Hirama.

Past positions of Dr Hirama are Rear Admiral (Maritime Self-Defense Force:Navy/Retired 1988), Professor & Director of Library of National Defense Academy (Retired 1998), Lecturer of Tsukuba University (International Relations/Retired 2002), Lecturerof Tokiwa University (Japanese History/Retired 2003). This article is the primary source of information on modern Japanese submarine (except Soryus and Post Soryus), and search procedure is as follows:

To access [6] Click on http://hiramayoihi.com/yh_e_top.html.

(1) Click "Papers"

(2) Search “English History”

(3) scroll down, then Click”Japao n l'auto defense”, Marines & Navales:Hors Serie Sous-Marins:Special sous-Marins Diesels(Paris:2004) (English version), which provides "History of the Japanese Submarine(After WWII) 

or

(4) for original Japanese language version Click "History of Japan Maritime Defense Force Submarine “

[7] Based on those of 12V25/25S for Oyashio [6].

[8] Unfortunatedly, output of 12V25/25S for Harushio-class shows contradiction in English version of [6] (English version 3100PS=2280kW & 3400PS (2500kW), Japanese version 3100PS=2280kW),and considering that Dr Hirama is Japanese, 3100PS =2280kW of mechanical output is used for Revised Table A (ver4).

[9] Since diesel engines are greatly dependent on the back pressure of the exhaust system in terms of their efficiency, decision on electrical output when snorkeling need information on the snorkel system. If the snorkel system of Oyashio.II -class is more effective than that of Harushio-class, mechanical output of 12V25/25S in Oyashio.II-class would show a higher output than the same 12V25/25S in Harushio-class.

[10] The charge of the battery must take place at the highest generator output to reduce the time of the submarine in snorting/snorkeling mode, or, the time in which submarine can be detecteded (indiscrete) would  increase. That’s why information on electrical output in snorting/snorkeling mode is quite important. But there is no information in [6].

In http://www.bmtdsl.co.uk/media/5045649/BMTDSL-Sub-Power-and-Propulsion-Confpaper-Pacific-Jan12.pdf page 2, “As an example the MTU 12V 396TE54 is rated at 1200kWe (electrical output) for the surface ship TE54 designation but when employed in the submarine version it is derated to 1000kW on the surface and 900kW when snorting”. This data (10% output reduction by snorkeling) was used to roughly estimate electrical output in snorting/snorkeling mode as reference. Since 12V25/25S and 12V25/25SB as well as 12V25/31S are younger diesels, designed after the MTU 12V396, they may show better efficiency than that MTU (less than 10% output reduction in snorting/snorkeling mode).

[11] The related standard specifies electric output of diesel being ---1800kW, 2000kW, 2500kW ---. I think that 2500kW of electrical output as target performance was decided at modification of 12V25/25SB to 12V25/31S at first, and at next, 310mm of stroke was decided to achieve this performance.

Anonymous