Depending upon where I am I use the escape option because you could have got aide from either other boats (increasingly unlikely) but also Bv 138s (again, increasngly unlikely) which also used diesel, albeit this option is rather dubious.

Obviously I use the trusty old dice method for calculating:
1940 - 1941: if I role 2 - 5 I 'escape'
1942: if I role an even number I 'escape'
1943: I role twice and if the product is 18 or better then I 'escape'
1944: I role twice and if the product is 25 or better then I 'escape'

I also add the extra distinction for dates:
Nord Atlantik I use 10.1940 - 1.1945
Atlantik and Süd Atlantik I use 10.1940 - end of Mai 1944

The distinction is that at least the Bv 138s of Luftflotte 5 still were operate from Norway (although I have to get within 950 kilometres of major bases like Bergen, Trondheim or Narvik for this to be of any help). I know it is a rather feint hope and perhaps ahistorical, but then SH3 doesn't really give the option of refueling at sea beyond the stock milk cow option..

I'm no mathamatician so I don't know if any one year - aside from 1941 - stands a better chance of surviving running out of fuel or not. But as a general rule I always turn for home - regardless of torpedo situation when I judge my reserves to be about 45%, taking the most direct route there. If I'm in the Süd Atlantik and based in Norway, then I usually just forgo the bonus points and drop that to 40% and then aim for somewhere like St Nazaire.

Does it happen during every patrol you run?
- Yes, it happens every patrol, but it does make sense that the engines would decrease in speed as the battery is drained.

Do you recharge your batteries while on the surface?
- yes, i recharge batteries on the surface.This is automatic.

Are using SH3 Commander , and if yes do you have the mulfuction and sabotage option checked?
- no, I'm not using SH3 Commander.

To answer a previous post, I don't leave port submerged. I would leave port surfaced, running at ahead full. I know that not wise, but wanted to get to patrol area asap.

I'm getting mixed opinions about fuel conservation. I mean if running submerged does not conserve fuel, how can you arrive at a patrol area that is over 3500KMs away without running out of fuel?

Easy , you travel on the surface at ahead one third. With calm weather , this gives you about 8 - 9 kts speed which is satisfactory cruising speed.
It takes more time but it saves fuel and lets you return to port safely(fuel-wise)

Use ahead full of flank for interceptions only.

Try your (nautical) mileage when speed is set to different levels. (and given time to achieve it) You'll see.

Thanks to all you mates for you input!....07.....:D

What about the milkcow mod?...does it work?

travel at 8 knots for long distance patrols this is the most fuel efficient speed:salute:

keep an engineer officer in the diesel room too

edit: yes, for the type VII, my apologies

I see ahead 1/3 is quite efficient, but takes forever!....:D

Fuel is blood :salute:

Different classes of boats will have different "most efficient" speeds. YMMV, never truer. Best thing is to assess the performance of your own boat. The "Report range at current speed" order lets you do that. Optimum cruise will usually be between 8 and 12 kts. Operational ranges for all boats of all nations were spec'ed and measured at 10 kts, so that's what the designers aimed for. On the outbound leg to your patrol area, try a few speeds. In clear safe water on a fair day, set TC 8 (to give your speed time to stabilize). Then just set each speed and quiz the Nav about range at that speed. IIRC, US military usage sets "Bingo" fuel - return to base - at range to base plus ten percent. You can get your range to base in various ways. But there's no need to guess or use rules of thumb, and no need to RTB with half a tank of gas, either.

This is pretty much how the R/L skippers did it. But, if you are eager to BSU and consider fuel management a dull bother, you can just uncheck "Limited Fuel" in the realism (sic) options menu and never have to worry about running out of fuel again.