Limited Fuel

[Freiwillige]

Its like any combustion engine in that the lower the RPMs' the lower the fuel consumption. You have to find that balance between fast enough to get there and fuel savings.

Its like your car. Sure you could get a hell of a lot further per tank if you idled everywhere you went at 15 MPH but you would take allot longer to get there. So you do 40 on average which is a good compromise for speed vs fuel savings

[Piggy]

Originally Posted by Robert Fulton

Thanks. Good explanation.

What about the my navigator, though? Is he incorrect in advising me that I get better range at 3kts?

Ive always found my range esitmated range at 3 knots is a lot less then it is at 9 knots, even though Im burning much less fuel.

The reason I say this is because Ive noticed the Navigator gives you the most range at ~9knots, but if you go to 3 knots your esitmated range is quite a bit lower even though you're burning a lot less fuel. At 3 knots you can stay on your patrol area for a long time, but you wont get very far at that speed?

I imagine endurance and range to be two different things?

If that makes any sense?

[GoldenRivet]

endurance is how long your engine will run over time

range is how far you will go at the current speed

as freiwillige pointed out you have to strike a balance between speed and efficiency. too slow and you dont cover much ground, too fast and you run out of fuel sooner

i have found that - if i want to go a LONG way on a tank of gas then right about 8 or 9 knots is perfect.

You can really stretch the fuel if you remain submerged all day long at ahead slow and then run surfaced all night long at 8-9 knots.

another problem we run into in SH3....

the map is a "Mercator projection"... ie it is a flat surface representation of a spherical world.

The SH3 world gets its information as to where land and ocean are from the map... so the world in SH3 itself is in fact completely flat too!!

the further you go from the equator north or south, the more distorted the map becomes, this is why Greenland on the SH3 map nearly dwarfs north America.

ideally, the game would use curved nautical charts... which - if you had a large enough wall you could tape all the nautical charts together end to end and they would form a massive circle of charts.

the end result, even though a real life U-boat would have no real problem leaving St. nazaire and heading to New York... the game has added a significant distance between the two locations by "flattening" the earth.... so GWX crew had to mod the ranges of the U-boats to compensate for this mathematical travisty.

[Piggy]

Originally Posted by GoldenRivet

the end result, even though a real life U-boat would have no real problem leaving St. nazaire and heading to New York... the game has added a significant distance between the two locations by "flattening" the earth.... so GWX crew had to mod the ranges of the U-boats to compensate for this mathematical travisty.

Yeah I noticed that the range my navigator gives me in my VIIC is more then that of a IXC, quite a bit more...

Must be using some new fangled "compressed fuel oil tank".. top secret!

PS: Before I realized how the map was stretched I was making runs to north america via a circular route north, somewhat like how an airplane would fly. Its shorter to go up north, across and then south rather straight across the (or around) the middle of the atlantic. Of course this doesnt make a difference in game, but it feels "real"...

[GoldenRivet]

sure it feels real... but do that great circle business in SH3 and your burning fuel you dont need to burn.

everywhere in the SH3 world the shortest distance is a straight line

[Nedlam]

Originally Posted by irish1958

Does anybody know what the average time per patrol per sub type per year? Also the average time at sea or number patrols until being destroyed or retired per sub type per year?

Go to Uboat.net and pick a bunch of different U-boats of the same type. It's easy to figure out the average time length for each boat and then take that info and get an average for the type of boat, whatever you pick. It's also fun just to read up on all the patrols.

[Robert Fulton]

Thanks, guys. I shall summarize to be sure I understand.

Range and endurance are different. Noted.

Range is greater at 3kts than at 8kts, but it takes longer to get there. Thus the 8-9kts recommendation is balanced, taking into account fuel usage and travel time. If one is solely concerned with maximum range (getting home on low fuel e.g.), then one should run at very low speeds.

Do I understand it correctly?

[GoldenRivet]

thw way i understand it is to set speed to 8 knots and head for the most direct route home. (or to the closest supply ship or sub)

how much fuel do you have? 50% 25% etc?

try this

set your speed to 3 or 4 knots and request range from navigator as i have escribed above.

then set speed to 8 knots and request range again.

whichever speed yields the best range use that!

[Pisces]

When I 'interrogated' my nav officer for fuel endurance (distance in km) at different speeds in every new uboot type, it gave ranges for speed that look like a bell curve ( __-^-__ ). As I left Willemshaven, in calm waves and wind, 8 knots being the economy-speed top at about 34000km for a type7b (one way trip). Even if you go rather slow (1-4knots) , the diesel you have won't get you very far. Just like going fast.

The following thread might have some more information:

http://www.subsim.com/radioroom/show...864#post835864

EDIT: p.s. my data is from GWX 2.1

[GoldenRivet]

thats a cute bell curve.

I have considered creating printable performance charts

[Wreford-Brown]

Originally Posted by Robert Fulton

Thanks, guys. I shall summarize to be sure I understand.

Range and endurance are different. Noted.

Range is greater at 3kts than at 8kts, but it takes longer to get there. Thus the 8-9kts recommendation is balanced, taking into account fuel usage and travel time. If one is solely concerned with maximum range (getting home on low fuel e.g.), then one should run at very low speeds.

Do I understand it correctly?

Check out this post: http://www.subsim.com/radioroom/showthread.php?t=137775.

Fuel economy is a function of how hard your engines are working, not speed. If you set your speed to a certain value, your actual speed may well be less due to bad weather and the effect of waves on your boat.

I've also done the bell-curve calculations for all boats and came up with the Fuel Economy mod. I tend to cruise everywhere on Ahead Standard but switch to the fuel economy setting if my patrol grid is a long way from home port.

[Pisces]

Originally Posted by Wreford-Brown

...
Fuel economy is a function of how hard your engines are working, not speed. If you set your speed to a certain value, your actual speed may well be less due to bad weather and the effect of waves on your boat.
...

How do you measure that? RPM? Or just throttle setting? (which as you know from your mod, is really a 'desired speed', which may not be attainable due to waves/wind). Please elaborate further.

[Wreford-Brown]

The only was to set your 'throttles' is to set the speed on your dial in the lower right of the screen. A given speed (usually between 7 and 8 knots) will give you the best endurance - if you go too slow your range will decrease.

As long as you set your desired speed to the most economical setting you will get the best range out of the boat but do not be surprised if your actual speed is less than the desired speed.

This is most easily seen in bad weather when your grey (requested speed) needle can be one or two knots ahead of your black (actual speed) needle.