Big problem, need help
 

Im in the east China sea, just finished a patrol with 47% fuel left. I need to get back to Australia but whatever route i choose i end up running dry right after Java and i dont have a save before this. I thought 47% would had been well enough but it seems i was wrong. Is there any other way i can get back home?

Have you tried adjusting speeds?
 

Your range will be substantially extended if you reduce speed to 2/3 or even 1/3- will take longer but use up much less fuel. What does your is your current max range?

Forgot to say im going 10 knots which is considered the optimal speed to save fuel. Im not sure how much range i got...

Also, make sure that your not charging up your battery. I had the same problem and my battery was slightly damaged and the engines kept trying to recharge it :)

That's not correct. Dropping below, as OP has said, 10 Knots or so actually drastically reduces fuel efficiency.

But yeah, disable battery charging incase there's damage. Your not ending your patrol due to damage are you? Because there could be fuel leaks as well.

Only the AA gun was damaged. I ended up changing the limited fuel setting in the save cfg file. There was just no way i could make it back home otherwise.

Yes i cheated, forgive me gods of sub simulators :(

You do what you have to to save the game. That said, you obviously used much less than 47% to get there in the first place. Something has to be wrong, and battery damage looks like the probably culprit. this is a known bug in SH4, and something to watch for.

Well it took about a quarter of the fuel to get there then i paroled a few spots and decided to head home at 50% thinking id have enough to get back but obviously i was wrong. Nothing was damaged other then my AA gun.

I just got transferred to a Gato class... Hows the tank on this version? Any bigger? More range?

This was a lesson learned the hard way. Once batteries/diesel busted, pray, plot, and play. a 50% indicated charge on a battery with damage will consume diesel unless you turn off surface recharge (to which I assigned a hotkey).

Also, I never recharge the battery except when under 25% pre-AO. Even with all maneuvers with aircrafts and randomly spawning destroyers.

Once in the AO, surface recharge is performed second nature.

Point is, with all gimmicks before actually reaching the AO, one charge (base charge) is enough.

With that being said, it differs according to AO, since dusting -off pearl and heading to Jap territorial waters you probably encounter less traffic in the 4k + leg, whereas, Brisbane-Java/Sulu would demand more drills and hence risk running dry in such shallow waters with frequent contacts dictates a frequent routing recharge, since underwater, your evasion depends in shallows on speed of RPMs being minimal, evading with range rather than depth.

I've had this issue as well. What I do is refit my boat at another American port (on the way to patrol area) to "top it off" before the long hauls. I usually run at 1/3 speed if I think fuel may be an issue.

Try running at 8 and a half knots.