Soryu Double and Single Hull Sections Diagram

Assembling detailed information on submarines is a “bit at a time” job - from comments “August 25, 2015 at 6:31 PM” http://gentleseas.blogspot.com.au/2015/08/ss-response-to-7-problems-with-japanese.html Soryu structural diagram above was provided.

Diagram made open source at http://livedoor.blogimg.jp/wispywood2344/imgs/8/b/8b3c1df9.png with the following notes:

The Soryu hull structure consists of six sections. From right-hand side head to left-hand side tail the:

i)  first section (head) has double and single hull structures [Pete Comment – complicated due to varying loads/considerations as bow streamlining, sonars, torpedo tubes, front escape tube and hatch to sail];

ii)  second, third and fourth sections have a single hull structure;

iii)  fifth and sixth sections have double hull structures. [Pete Comment – complicated due to rear escape tube and rudder-propeller hydrodynamics considerations]

The double hull consists of the outer non-pressure hull (non-magnetic alloy) and the inner pressure hull (magnetic NS-80). The inner pressure hull (NS-80) is not as strong as the single pressure hull (NS-110), because the outer hull (alloy) shows high strength.

The single pressure hull is made of low magnetic NS-110, in S’s opinion.

At a comment on August 28, 2015 at 12:38 AM S added – Earlier post WWII Japanese submarines has been using double hull structures, but from 1994 Oyashio class submarins adopted a hybrid single and double hull structure. In part this facilitated the introduction of further sound absorber material and a long flank sonar array.

S added comments commented about the German designed Type 214 submarine that also use a flank sonar array. The 214’s single hull structure is made of HY-100 [1] or HY-80/HY-100 [2]. S also noted that in the 1980s DSTO of Australia’s Department of Defence reported properties of HY-100 and highly appreciated it [3]. But, I worry about the combination of following two factors which may make a HY100 hull relatively higher magnetic. These factors are: i) relatively low contents of Ni (2.67-3.57%) and Cr (1.29-1.86) (see Table 1a, page 10) and concerning the same DSTO document [4], ii) single hull structure in which hull is directly exposed to surrounding water without shielding by a non-magnetic alloy. At present HY-100 may be adequate but we should think of future advances in ASW magnetic detection technology.

[For a future Australian submarine] To achieve overall low magnetism for this submarine (as it will not use NS-110) new low magnetic and high strength steel is needed for the single pressure hull, i.e. first partial area and second/third/fourth areas.

Please connect with - Submarine Matters' Japanese Submarines - Critical operational life and hull cutting issues, August 7, 2015. 

Pete Comment

So given hybrid single-double designs the difference between “double-hulled” and “single-hulled" submarines is not as distinct as is generally thought. Rather it is as complex as most other submarine matters. In the absence of NS-110 use there are various steels from HY-100 and approaching NS-110/HY-156 that may be appropriate.

Pete