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Originally Posted by Roger Dodger
S-Boat (Group I)
Propulsion: 2 x New London Ship and Engine Company (NELSECO) diesels, 1,200 hp (895 kW) each
2 x Electro Dynamic ( S-1, S-30- S-35), Ridgway ( S-18, S-20 through S-29), or General Electric ( S-36 through S-41) motors, 750 hp(550 kW) each
120 cell Exide battery
two shafts
Speed: 14.5 knots (27 km/h) surfaced; 11 knots (20 km/h) submerged
Range: 5,000 miles (8,000 km) at 10 knots (19 km/h) surfaced
Submerged Range/Endurance not found
Gato Class
Propulsion and power:4x diesel 5400hp
4x electric motors 2740hp
2 × 126- cell Sargo batteries
2 shafts
Speed:
Surfaced:20.25 design/ 17knots operational
Submerged:8.75knots
Range:
Surfaced:12,000nm at 10knots
Submerged:95nm at 5knots
Endurance:48 hours at 2 knots (4 km/h) submerged
75 days on patrol
Source: http://en.wikipedia.org/wiki/List_of...ed_States_Navy
Given the above specs, I would expect the S-Boats to have 1/2 the endurance submerged and take twice the time to fully re-charge its (single) battery compared to the Fleet Boats. |
Well, I wonder if batteries really work the way implied by these Wikipedia numbers. I remember seeing the 2 knots info before from other sources, but I don't really remember seeing the 5 knot info before - I'm going to have to try to find my old info that came from generally more reliable sources, but for now we'll deal with the Wikipedia numbers. For the Gato class, the Wikipedia info states both:
1. Range:
Submerged:95nm at 5knots; and
2. Endurance:48 hours at 2 knots (4 km/h) submerged
Although this struck me as weird at first, upon further reflection this seems like it could be correct - while it seems obvious that the batteries won't last as long (in time) at the higher 5 knot speed as they will at the lower 2 knot speed, it's not clear why the batteries wouldn't be able to propel the boat about the same distance on the same amount of stored charge/energy regardless of the speed, and (per the Wiki numbers) 48 hours at 2 knots would be 96nm, essentially the same as the 95 nm listed at 5 knots. I don't know whether travel at the higher 5 knot speed is inherently less energy-efficient than traveling at the lower 2 knot speed when traveling on batteries or not. With cars and their internal combustion gas-powered engines, once you reach some level going faster does burn more fuel per mile, but maybe it's not like that with electrically driven motors, at least maybe not within that relatively narrow speed range of 2-5 knots - does anybody know for sure?
However, regardless of whether both of these range/endurance formulations are correct, the game with the TM values mentioned above cannot achieve close to either one. As indicated in my post above, tests at 2 knots routinely generate ranges about 2/3rds what they "should" be. Just for grins, I just ran a test at 5 knots, and the batteries ran out in just 8 hours, after covering only 40nm - somewhat less than half as far/long as they should have been able to last if the Wiki numbers are correct.
Given the remote likelihood that enemy forces will stay on station and keep your sub pinned down for even 8 hours much less 30, this battery problem doesn't have much impact on convoy attacks in the open sea lanes, so maybe folks don't see this as a high priority problem to fix. However, this lack of battery staying power wreaks havoc on the ability to operate realistically in shallow waters near enemy territory (for agent/commando insertions, harbor recon missions, etc.), which is a big part of what makes a PTO subsim different in concept from an Atlantic simulator like SH3. Besides, battery propulsion of a submerged sub is a pretty central part of what being a sub simulator is all about, so it would be really nice if somebody could figure out how to get this fixed so the game would model this more correctly.