Fuel Efficient "cruising" speed in 1.3

[Harry Buttle]

Is there a particular speed setting that equals fuel efficient cruising in 1.3?

ie 2/3 speed or is it a per boat setting and if so, is that info available anywhere?

Thanks for any responses.

[John Channing]

From what I have read 10-10.5 kts is the most efficient speed.

JCC

[switch.dota]

S-Class -> 5 - 5.5 knots is the optimal cruise speed
Fleet Boats -> 10 - 10.5 knots.

Out of the 5 predefined options (1/3, 2/3, std, full and flank) the best fuel efficiency is at 2/3 (it isn't optimal - to get optimal efficiency set speed manually).

[Kamikaze]

I just tried my first mission post 1.3 patch . . . and ran out of fuel!

This is using a GATO class and I usually cruise at 2/3 alternating between battery and diesel. My mission was to leave from the Asiatic base and go to the top of the Phillipines. NO WAY could I get there! Half way I'm already at the limit of my range. Is this correct?? Is there a better way to do this?

Here are more details :
at 4AM I submerge (100ft) and set speed to 1/3, at 1200hrs I increase speed to 2/3 until batterys are almost drained (usually around 1730 hrs). Run surfaced at 2/3 until batterys are charged and then submerge. Repeat.

Open to any suggestions. Thanks in advance.

[PepsiCan]

I just tried my first mission post 1.3 patch . . . and ran out of fuel!

This is using a GATO class and I usually cruise at 2/3 alternating between battery and diesel. My mission was to leave from the Asiatic base and go to the top of the Phillipines. NO WAY could I get there! Half way I'm already at the limit of my range. Is this correct?? Is there a better way to do this?

Here are more details :
at 4AM I submerge (100ft) and set speed to 1/3, at 1200hrs I increase speed to 2/3 until batterys are almost drained (usually around 1730 hrs). Run surfaced at 2/3 until batterys are charged and then submerge. Repeat.

Open to any suggestions. Thanks in advance.
Running on both batteries and diesels uses more fuel than just using diesel. While you are at the surface running your diesels, you're also charging your batteries. So, in essence, until your batteries are recharged, you run at 2/3 speed, but you're using all your diesels as if you were trying to go at flank speed. Secondly, the energy from burning diesel is not transformed 100% into battery power. A large percentage gets lost due to heat, friction etc.

So, stay surfaced and don't push the gas pedal!

[Nafod81]

I generally travel at ahead 1/3 which is 5 knots for S Boats and 8-9 for Fleet boats.

Spending any considerable amount of time above that adversely impacts endurance considerably.

e.g.

I was able to complete a patrol from fremantle to the Luzon Straight and back in an S-boat in this manner.

Additionally in a Porpoise class boat traveling back to Midway from the Southern inlet of the inland sea at 1/3 uses 25% of fuel reserves. Traveling the distance with 75% of fuel reserves remaining at 2/3 left me 400 nm short of the base :doh:

I only use ahead 2/3, Standard and Full when intercepting convoys or task forces, and flank only in battle situations.

One really just needs to take it slow and enjoy the scenery:)

[Kamikaze]

OK, good answers. Thanks. So when charging batteries one should be at 1/3 speed? For best fuel effieciency?

How important is it to actually complete the mission goals? Does it matter if you sink a good amount of tonnage?

I redid my previous mission and did better. I left the lower Asiatic base, topped off at the base just North of it. Then proceeded trying to use 10 knots as my surface cruise speed. This is just over 2/3 setting for the GATO (when charging). I encountered 3 small convoys sinking 10 Large/Medium ships and 1 Large Transport. I did not complete the mission goals but returned to port due to low torpedoes. I was awarded the Medal of Honor (go Figure).

It didnt seem to matter that I did not get to my mission location. Which I think is unreachable in my current ship!

[tycho102]

1. So when charging batteries one should be at 1/3 speed? For best fuel effieciency?

2. How important is it to actually complete the mission goals? Does it matter if you sink a good amount of tonnage?
1. Yes, something like that. The best way to find the answers to your questions is to download one of the keyboard configuration mods. One of them has presets already made in the config file, the other is a program that alters the config file with your choices.

Range-at-Current-Speed is the report you're looking for. Hit that at various speeds in calm 1-2m/s winds, and you'll find your best point of sail. It tends to be close to the 2/3's speed setting. In Gato boats, it's right around 11kts. In Balao boats, I believe it's 12kts. So when you're charging batteries, I think your engines are running at "standard" power, and whatever you're not using for propulsion goes to your batteries. If you try running at "full" or "flank", you'll see your charge rate drop down to almost nothing because you're above the "standard" power curve. To get some speed and decent recharge rate, you'll want to run slow. It also means you're not really going to get extra range by using your batteries like Type-7 Krauts did.

2. You get set renown for it. 200 (reach patrol zone) and 500 (complete objective), I think.
Sinking a minimum amount of tonnage may be one of the requirements.

[Kamikaze]

Thanks Tycho! I'm using the TM MOD so the Range-at-Current-Speed button is already setup.

Very Good . . Thanks to all who have taken time to reply. I'll just have to experiment and hope for the best. I certainly know NOW to keep a close eye on that fuel level!

That GATO is a fuel whore!

[chopped50ford]

i agree, 10-10.5 are the best speeds.

[Capt Jack Harkness]

I just tried my first mission post 1.3 patch . . . and ran out of fuel!

This is using a GATO class and I usually cruise at 2/3 alternating between battery and diesel. My mission was to leave from the Asiatic base and go to the top of the Phillipines. NO WAY could I get there! Half way I'm already at the limit of my range. Is this correct?? Is there a better way to do this?

Here are more details :
at 4AM I submerge (100ft) and set speed to 1/3, at 1200hrs I increase speed to 2/3 until batterys are almost drained (usually around 1730 hrs). Run surfaced at 2/3 until batterys are charged and then submerge. Repeat.

Open to any suggestions. Thanks in advance.
Running on both batteries and diesels uses more fuel than just using diesel. While you are at the surface running your diesels, you're also charging your batteries. So, in essence, until your batteries are recharged, you run at 2/3 speed, but you're using all your diesels as if you were trying to go at flank speed. Secondly, the energy from burning diesel is not transformed 100% into battery power. A large percentage gets lost due to heat, friction etc.

So, stay surfaced and don't push the gas pedal!

Not to rant, but American submariners called their engines diesel generators for a reason: They were not directly connected to the propshafts and served solely to generate power for the motors and batteries (So sayeth Richard O'Kane in his book Wahoo). Because of that, I think the animation of the props stopping then starting after dive is inaccurate, as well as the sound of the motors coming online. Really the only thing that should happen is the engines shut down...