Fuel: Discuss these two choices

[Ducimus]

Which would you prefer and why?

Realistic:
12,000 NM @ 10 kts ( loosely translates into "ahead 2/3rds")

Arguably, not realistic:
12,000 NM @ 12 kts. (loosley translates into "Ahead standard")

[Misfit138]

I'm a realism junkie so...

Realistic:12,000 NM @ 10 kts ( loosely translates into "ahead 2/3rds")

Just wished that with this option there would be also an option to call a tug boat if on friendly territory

[orangenee]

Not really realistic for me, if they modelled the world correctly then I'd probably go for realistic but they didn't.

[theluckyone17]

I'm for realism, myself... 'course, I'm with the guys above, wishing that wind/current would have an effect, along with the ability to call in for a tender or some other assistance.

There's been a few times when I'm heading back to port. I've got fuel to get there, plus a nice reserve if I need to dive or replot a few times. I'm sweating, though, since I can't remember exactly when my base is overrun by Jap's, and I'm going to have to divert to a different, more distant base... that I don't have enough diesel to reach.

But if I can't get all that, then I still want realism... 'cause it's my fault if I didn't leave enough reserve in. No matter how big that reserve needed to be ;).

[Snuffy]

Real works for me ... :)

[Ducimus]

Ok, i had an idea, and the idea is obviously bad, and i agree its bad. Thats ok, just something else i DON'T need to do :P

[switch.dota]

One problem, Duci: ahead 2/3 is 8, not 10 knots. Either increase engine power to 48% (from 40%) for 2/3 or modify efficiency. I have modded ahead standard to a flat 50% engine power for the sole purpose of having 10 knots at the touch of a button. I don't fancy manually setting the speed everytime I surface (up to 10 times a day). It's repetetive and only gets on one's nerves.

[Ducimus]

One problem, Duci: ahead 2/3 is 8, not 10 knots. Either increase engine power to 48% (from 40%) for 2/3 or modify efficiency. I have modded ahead standard to a flat 50% engine power for the sole purpose of having 10 knots at the touch of a button. I don't fancy manually setting the speed everytime I surface (up to 10 times a day). It's repetetive and only gets on one's nerves.

If it wasnt for the fact that those engine telegraph speeds ALSO effect underwater endurance, id have changed it already. I feel the 2/3rds, as is, is needed because of submerged performance. Realistically you don't gain that much distance by going at 10 kts. I've always known that 9-10 kts is the best, for years, but i never do it. Ahead 2/3rds the whole time (8 kts), and i've never been short on fuel. *shrug*

[switch.dota]

I use

1/3 = underwater silent speed / daytime submerged speed
2/3 = underwater cruise speed
std = surface cruise speed (modded to around 10-10.5 knots)
full = 80% engine power
flank = good ol' one double 'oh engine power.

[Ducimus]

You know i just ran myself over to the bungo suido area, and i swear to you, i tried both 10 kits and 8 kits and my total estimate milage at 10 kit was acutally LOWER then if i ran at 8 kts. Maybe it varies on boat type, but i often think that magical speed of 10 kts is over rated.

[C DuDe]

I'll go realistic when a tug boat is available.

[switch.dota]

You know i just ran myself over to the bungo suido area, and i swear to you, i tried both 10 kits and 8 kits and my total estimate milage at 10 kit was acutally LOWER then if i ran at 8 kts. Maybe it varies on boat type, but i often think that magical speed of 10 kts is over rated.
You should use TM's Max Range @ Current Speed estimate. It pretty much proves that the optimal speed is a little above 10. 8 knots is pretty similar to 11-12 knots in terms of range.

[Redwine]

I like the realistic option, but...

When you use the plotter course tool... and set a new waypoint, the sim move the enegine telegraph to ahead standard... if you forget to move it to the "economy" position, you may loss fuel...

Then, i think so it is better to have the "economy" speed in the position at wich the sim moves the telegraph automatically after stablish a new waipoint to avoid indesired errors.

I prteffers the option showed by "Switch.dota" above.

:up:

[switch.dota]

Offtopic: I wanted "switch" but it's taken :(

[nomdeplume]

Redwine makes a real good point. I voted realistic, but the whole "the AI sets the speed to Standard by default" thing is probably enough to change my mind. After all, it is called "standard", so surely that'd be the standard cruising speed?*.

I kind of like 2/3rd in that it makes every preset kind-of useful:

1/3rd is for dawdling, or very fast charging of batteries while still moving.
2/3rd is for best fuel efficiency.
Standard is slightly less efficient, but useful when chasing or ending-around the slower convoys (or just keeping ahead of them while you wait for better weather or what have you). Doesn't slow down charging too much, either.
Full is for ending around, while still giving the batteries a tiny charge.
Flank is for when all hell's breaking loose. The speed gain is marginal at best, but it sure feels good to yell "AHEAD FLANK!" when the s hits the f.

I think the above also map reasonably to engine usage (in terms of propulsion), from using the auxiliary for propulsion up to using all four main engines plus the aux for propulsion. Probably incorrect, but it "makes sense" to me. :)

Ultimately, I don't really care what the optimum setting is, so long as it's one of the presets (or at least if it's close enough not to make a significant difference to your endurance).

* - I guess "standard" is the cruising speed in peace time, when endurance isn't so important and they tend to refill constantly anyway.

[Sailor Steve]

Not really realistic for me, if they modelled the world correctly then I'd probably go for realistic but they didn't.
An excellent point. I voted for absolute realism, but you're right - their world isn't round.

[AVGWarhawk]

This is were I'm lost on the realism concerning fuel. From what I understand the 12000 nm was running at ahead standard or around 14-15 kts. We are stop gapped to 10.8 kts to make the patrol area and make it home. Can the fuel consumption be modded so we can run at 14-15 kts but still have the fuel reduced at the same rate as if we were running at 10.8 kts?

[Ducimus]

Can the fuel consumption be modded so we can run at 14-15 kts but still have the fuel reduced at the same rate as if we were running at 10.8 kts?

Offhand, i don't think it can. Fuel or battery consumption seems to be a result of RPM"s. The more RPMs, the faster the energy loss. The only thing i can think of, is to maybe change the engines power. Im not sure, but i think engine power might be relating to how much energy it draws in order to run. Reduce the engine power, maybe you'll reduce the fuel needed to run it. Sounds funky, but remember theres still a "top speed" variable to play with. In theory if you lower its power, and increase its top speed you've made it more efficient.

[chopped50ford]

I'm a realism junkie so...

Realistic:12,000 NM @ 10 kts ( loosely translates into "ahead 2/3rds")

Just wished that with this option there would be also an option to call a tug boat if on friendly territory

Im for these idea's.

Is a Tugboat possible?

[Redwine]

Can the fuel consumption be modded so we can run at 14-15 kts but still have the fuel reduced at the same rate as if we were running at 10.8 kts?
Offhand, i don't think it can. Fuel or battery consumption seems to be a result of RPM"s. The more RPMs, the faster the energy loss. The only thing i can think of, is to maybe change the engines power. Im not sure, but i think engine power might be relating to how much energy it draws in order to run. Reduce the engine power, maybe you'll reduce the fuel needed to run it. Sounds funky, but remember theres still a "top speed" variable to play with. In theory if you lower its power, and increase its top speed you've made it more efficient.
Mmh... may be i am wrong Ducimus... but i think so it is posible.

The maximun range speed is just that adjusted on the sub .sim file.

The fuel compsumption seems to be not related to the engine RPM, because, if into the files is adjusted in example 12000 miles at 10knt.... if you sail at 11knt, your range become reduced.... but... if you sail at 8knt, at lower RPM, the range is reduced too, and fuel compsumption is increased.

You can check it using the Shift+G function, "Max Range at this present speed".

May be i am wrong... but if we can an economy speed of 15knt in example, the only thing we need is to adjust it into the sub file.... as the speed for the max range.

But then, when you will sail at 10knt you will spend more fuel than at 15 knt.

I am not sure if the team made it intentionally, but it is real... all alternative motors have an efficience curve, it is at top of the torque curve, if you use the engine at max torque vale, you save fuel, if you use it over or under you losse fuel.

In example, my car has a max torque at 2600 rpm, if i use it at 4500rpm, or 2000rpm i lose fuel.

The max range is 2600rpm wich is 90km/h at 5th gear into the gear box.

if i run on 5th, at 40km/h or 140km/h i expend more fuel than at 90km/h.

:up:

[AVGWarhawk]

OK Redwine, you are great at file alteration and modding. Do you think this can be done?

[Ducimus]

I think he just said it can?

Im not saying it can't be done, im just saying im skeptical if it will work out the way we'd want it to.

[JSF]

This is were I'm lost on the realism concerning fuel. From what I understand the 12000 nm was running at ahead standard or around 14-15 kts. We are stop gapped to 10.8 kts to make the patrol area and make it home. Can the fuel consumption be modded so we can run at 14-15 kts but still have the fuel reduced at the same rate as if we were running at 10.8 kts?

Excellent point! Everything I have ever read concerning cross Pacific transits to patrol areas agrees with this speed factor.

[Sailor Steve]

Before you run with that ball you might actually want to look at some sources:
http://www.valoratsea.com/gato.htm
http://www.valoratsea.com/Sclass1.htm
http://www.valoratsea.com/Salmon1.htm

I had a look in Conway's, and it's the same: all ranges are given at ten knots. U.S. surface ships are given at 15 knots, but I suspect that 10 was still more economical; 15 just allowed faster transit times, and they could refuel at sea.

[Redwine]

This is were I'm lost on the realism concerning fuel. From what I understand the 12000 nm was running at ahead standard or around 14-15 kts. We are stop gapped to 10.8 kts to make the patrol area and make it home. Can the fuel consumption be modded so we can run at 14-15 kts but still have the fuel reduced at the same rate as if we were running at 10.8 kts?
Excellent point! Everything I have ever read concerning cross Pacific transits to patrol areas agrees with this speed factor.
OK Redwine, you are great at file alteration and modding.

Not true ! but many thanks... i am only a "persistent" dummy... but i am capable to stay 4 months tweaking up to reach what i want !


Do you think this can be done?

I think he just said it can?

Im not saying it can't be done, im just saying im skeptical if it will work out the way we'd want it to.
Yes... i think so it can be done.

But i am not sure... it is my supouse.

Let me to made a small pack of files to upload...

But as Sailor Steve wrote... will be not real, the fuel economy speed was 10knt not 15knt.


Before you run with that ball you might actually want to look at some sources:
http://www.valoratsea.com/gato.htm
http://www.valoratsea.com/Sclass1.htm
http://www.valoratsea.com/Salmon1.htm

I had a look in Conway's, and it's the same: all ranges are given at ten knots. U.S. surface ships are given at 15 knots, but I suspect that 10 was still more economical; 15 just allowed faster transit times, and they could refuel at sea.

[Ducimus]

You know, in light of this thread :
http://www.subsim.com/radioroom/showthread.php?t=120398

I am seriously contemplating bringing fuel in TM back to stock levels. . Stock is 15,000 NM @ 10 kts. THe historical spec, is around 12,000 NM @ 10 kts, thats 3,000 NM more range in stock. Now ive always wondered if the historical spec is taking into account of fuel being stored in ballast tanks.

To play "Make beleive" for a minute here. Lets assume that 12,000 NM @ 10 kts is NOT taking account of fuel in ballast. That means that, theortically, ubi's 3,000NM over the spec, IS. That 1,500 NM per ballast tank (as i beleive two tanks were used for this purpose). So by that logic you could, go back to stock fuel, and feel ok about it.

edit: yeah slightly off topic i know, just thinking aloud.

[Sailor Steve]

Given the point made by orangenee about the earth modelling (there is no great circle route in the game) you're probably right about the extended stock range.

[Redwine]

You know, in light of this thread :
http://www.subsim.com/radioroom/showthread.php?t=120398

I am seriously contemplating bringing fuel in TM back to stock levels. . Stock is 15,000 NM @ 10 kts. THe historical spec, is around 12,000 NM @ 10 kts, thats 3,000 NM more range in stock. Now ive always wondered if the historical spec is taking into account of fuel being stored in ballast tanks.

To play "Make beleive" for a minute here. Lets assume that 12,000 NM @ 10 kts is NOT taking account of fuel in ballast. That means that, theortically, ubi's 3,000NM over the spec, IS. That 1,500 NM per ballast tank (as i beleive two tanks were used for this purpose). So by that logic you could, go back to stock fuel, and feel ok about it.

edit: yeah slightly off topic i know, just thinking aloud.

Not sure of that Ducimus... i suspect the game use statute miles, (+- 1.65km) instead nautical miles.

Then when i tweaked my files i let this value at stock value 15000, really... if i am right, it must be +- 13600...

12000nm are about 13600 stm.



Here a little pack of tweaked files containing the sub.sim files with the max range speed adjusted to 15knt....

If some body want to check if the economy speed is moved or not now up to 15knt here you have.


Download here :

http://files.filefront.com/Subssim+fileszip/;8312601;;/fileinfo.html

[Ducimus]

... i suspect the game use statute miles, (+- 1.65km) instead nautical miles.

I was wondering that myself until i tried it ingame. Orginally i modded diesals to be 12,000 @ 10 nm. This is almost the exact range the NA would report if i was at a speed of 10 kts. In TM, he will report higher then that, because i "faked" the fuel range and changed it to 12,000 @ 10.95 kts. It in effects give around 1000 to 2000 more NM's out of the NA's report. edit: now having said all that, i still could be wrong, NA reports always were a little "fuzzy" to say the least.

[Ducimus]

Sorry guys, im still stuck on fuel. I swear i have a fetish with it.

I suppose its about time i look in a technical manual. I hate reading tech manuals. Ever see a tech manual from the USAF? its so cut and dry, you want to fall asleep after 5 mins of reading. Sadly a USN manual from 1940's is more easily understood then a current AFTM.

http://www.maritime.org/fleetsub/diesel/chap5.htm#5A
http://www.maritime.org/fleetsub/diesel/foldout/fig5-01.htm

Fuel oil tanks.
They vary in size, but normally have capacities of from 10,000 to 20,000 gallons each. Most modern submarines have four of these tanks. In a typical installation (Figure 5-1) they are numbered No. 1, No. 2, No. 6, and No. 7.

Fuel ballast tanks.
Most fleet type submarines have three fuel ballast tanks varying in capacity from about 19,000 to 25,000 gallons. On a typical installation (Figure 5-1), the fuel ballast tanks are numbered No. 3, No. 4, and No. 5.

So lets assume a the following scnearios on on fuel oil tanks, and fuel ballast tanks

Worst case:
Fuel oil tanks @ 15,000 gall. each X 4 = 60,000 gallons.
Fuel ballast tanks @ 19,000 gall each X 3 = 57,000 gallons

97,000 total gallons.

Middle ground:
Fuel oil tanks @ 19,000 gall. each X 4 = 40,000 gallons.
Fuel ballast tanks @ 22,000 gall each X 3 = 66,000 gallons

106,000 total gallons.

Best case:
Fuel oil tanks @ 20,000 gall. each X 4 = 80,000 gallons.
Fuel ballast tanks @ 25,000 gall each X 3 = 75,000 gallons

155,000 total gallons.

Now, IF an average fleet boat does 12,000 NM with 96,000 gallons of fuel oil. ( http://www.navsource.org/archives/08/08206.htm ) That means its burning on the average 8 gallons of fuel per 1,000 NM.

So then

Worst case
97,000 total gallons. / 8 = 12,125

Middle ground
106,000 total gallons. / 8 = 13,250

Best case
155,000 total gallons. / 8 = 19,375

[AVGWarhawk]

I think he just said it can?

Im not saying it can't be done, im just saying im skeptical if it will work out the way we'd want it to.

Understood. What we want to accomplish and have it work the way we believe it should are two different things, no doubt! Especially when only having the use of 0 and 1 in the computer world.

[AVGWarhawk]

The worst part of all this....if we had control of engines individually perhaps the fuel issue would be a non-issue. Just run on two or one to get to the patrol area.:damn:

[CaptainHaplo]

Well when it comes to modding fuel consumption - this is something I know a little bit about. Note - a little is probably a generous estimate - but I fiddled with range and speed a bit to get the nuke boat mod out. Here is what I found if it helps...

You can mod the range to whatever @ whatever speed... so for Nuke boats I made the range like 99million miles at say... 42 knots - which was max speed for the boat in question. So to get a balance that your looking for - just decide what you want true "best speed for fuel consumption" to be in knots (and you can make it vary by boat type obviously - but do be kind and publish what you set it at please!) - then decide what range that should give you. That speed the game will use as "optimum" for fuel calculations, and then will refigure based on if you speed up or down from that setting. Its not perfect because we cant get a boat to have exactly historical ranges at different speeds - but we can get the max range at "optimal" speed....

For anyone that wants any input or help with this - I will do what I can to help if you like. Just post or pm me.

[tycho102]

Now, IF an average fleet boat does 12,000 NM with 96,000 gallons of fuel oil. ( http://www.navsource.org/archives/08/08206.htm ) That means its burning on the average 8 gallons of fuel per 1,000 NM.
I thought that was low until I saw that's for a Gar. At MEP, I might believe 8gal/1-nautical-mile.:D
That would be 4 gallons per engine and that's about right.

[Ducimus]

Hmm yeah i think your right, i put a few too many zero's in there, Still though, it adds up.

[donut]

Return to course,sets engine annunciator to Std. it would be handy,fuel wise to have it set 2/3rds instead,if we are to use 8-10Kts for best fuel consumption. just a thought:huh: :hmm: Good game play:yep:

[Theraven]

I guess this is nitpicking but if you're thinking of modding anything based on these numbers:


Worst case:
Fuel oil tanks @ 15,000 gall. each X 4 = 60,000 gallons.
Fuel ballast tanks @ 19,000 gall each X 3 = 57,000 gallons

97,000 total gallons.

Middle ground:
Fuel oil tanks @ 19,000 gall. each X 4 = 40,000 gallons.
Fuel ballast tanks @ 22,000 gall each X 3 = 66,000 gallons

106,000 total gallons.


60,000 + 57,000 = 117,000 for worst case and

19,000 x 4 = 76,000

so it would be:

76,000 + 66,000 = 142,000 for middle ground.