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.