April 5, 2017

Part 2: FC-AIP is added to the LABs used in Part 1.

In Part 1: LABs: Hypothetical Snorting times, Crew shifts & Battery discharge schedules of April 3, 2017 Anonymous illustrated a submarine operating on Lead-acid batteries (LABs) charged by diesels only. The mission might perhaps be patrolling a SOSUS line between Guam and towards norther Luzon and back.

This mission could be described as medium-dangerous. The main threats could well be Chinese sensors and weapons on many platforms (regular maritime patrol aircraft (MPAs), SSKs, SSNs, regular surface ship patrols, satellites, perhaps large UAVs). If the Chinese are really organised they may have strung their own SOSUS arrays along and/or across, our friendly submarine's path.

The friendly submarine's response may be greater discretion, in part achieved by some reliance on AIP to evade the fortunately regular Chinese MPA and surface ship patrols. Fuel-cell (FC) AIP was selected over other types because it may be more efficient if it (a usually gradual chemical reaction) can be prepared a few hours in advance of use. 

Using FC-AIP, in grey on Table 2 and Figure 2 below, negates the need for two, relatively noisy, diesel snorts per 24 hours. Only 1 x 2 hour snort at night is required, perhaps 7 hours per day for several 16 days. A reserve of AIP propellants is retained for emergencies (maybe 5 days of use).  

Table 2 (below) represents:
- the times, over a 24 hour period, for operation on LABs (in purple), snorting (green) and
   FC-AIP (grey) 
-  in the final row, the Three Crew Shift Working system for FC-AIP/LABs-submarine. In
    three shift working system, submariners work for 6 hours and rests for 12 hours. (red 
    = shift A, yellow = shift B, blue = shift C)
time
18
19
20
21
22
23
24
01
02
03
04
05
06
07
08
09
10
11
12
13
14
15
16
17
18-24
























00-06
























06-12
























12-18
























Shift


























MW
























10.05
























10.00
























9.75
























9.50
























9.25
























9.00
























8.75
























8.50
























8.25
























8.00
























7.75
























7.50
























7.25
























7.00
























6.75
























6.50
























time
18
19
20
21
22
23
24
01
02
03
04
05
06
07
08
09
10
11
12
13
14
15
16
17
Figure 2 (above) Represents electrical chage or capacity changes over time for this friendly FC-AIP/LABs-submarine (with 3 working shifts working). The charge is at its lowest (6 to 7 MW) immediately before the 2 hours of snorting, which restores charge/capacity to 10 MW, followed by 7 hours on AIP.

Thanks very much to Anonymous.

3 comments:

Anonymous said...

Hi Pete

Three shift working system is based on US submarine system with three sections [1].

Considering adverse effect of accumulated fatigue of crews, operation period for two shift working system is shorter than that of three working sytem. In the case of 50 days operation (20days transition, 30days surveillance), FC-AIP will provides drastic improvement in submerge performance.

I think contribution of FC-AIP for 214-sub is bigger than that of 212A-sub. Because 212A-sub equips with single diesel generator [2], all LOx can not be consumed considering failure of generator. For 214-sub with dual diesel generators [3], all LOx can be consumed.

[1] https://en.wikipedia.org/wiki/Watch_system
[2] https://it.wikipedia.org/wiki/Classe_U-212
[3]https://de.wikipedia.org/wiki/U-Boot-Klasse_214

Regards

Peter Coates said...

Thanks Anonymous

I'm not precisely sure what watch system Australian Navy submariners use but given the long missions probably the 3 watch.

Interesting if Australia adopts FC-AIP for Shortfin.

Regards

Pete

Anonymous said...

Hi Pete
[with CORRECTION BELOW]

In my opinion, RAN used 2-watch system [2], and now uses 3-watch system [1, 3].

Life in submarine is tough, especially for officer. Captain of J-submarine is extremely bussy, he can not sleep well. Adoption of LIBs or AIP reduces the numbers of snorkeling which puts a great deal of strain on crews [4].

[CORRECTION Situation is same for RAN [5]]. As improvement of life in submarine is one of the key issues for RAN [3], I believe that Shortfin will definitely equip with LIBs and/or FC-AIP.

[1] http://www.navy.gov.au/sites/default/files/documents/Submarine_Workforce.pdf
“NAVY’S RESPONSESES TO THE RECOMMENDATIONS OF THE SUBMARINE WORKFORCE SUSTABILITY REVIES”.by R.H.Cane, RAN Chief of Navy, 8 April 2009
Page 11, Navy “AGREED” on “14 Respite Guideline “

[2] http://www.navy.gov.au/sites/default/files/documents/Submarine_Workforce.pdf
”REVIEW OF OF THE SUBMARINE WORKFORCE SUSTABILITY REVIEWS” undertaken by REAR ADMIRAL R.C. MOFFITT AO, RAN, page12
“Navy’s boats run in two watches at sea all the time. Works has commenced to design a three-watch system, for which revised scheme of complement will be required.”

[3] ibid, page 17, Key Observation
“Navy must give submariners a strong commitment to allowing respite and providing much better predictability, then deliver on that commitment reliably , consistency and in a sustaine manner. Changes are needed urgently to the way in which the submarine capability is managed to deliver this outcom.”

[4] ibid, page 11
“Conventional submarines spend a lot of time at periscope depth, which puts a great deal of strain on people and equipment.”

[5] ibid, page 20 “3.4.1 Officers”
“There is widespread agreement among officers and sailors that the average work day for an officer at sea is around 18 hours and can be as high as 22 hours in period of high activity.”

Regards