Cruise Speed

[BenG]

I'm just wondering what Cruise speed people use (and which is the best/most realistic) when sailing to and from Patrol Zones, and when just searching (i.e. not sailing to a contact).

I use 10 Knots on a Type VII (this is shown as ahead 1/3 (2nd Notch) on the telegraph).

[Rose]

Haha I'm not sure how many times this has been asked -- but its been alot. Let me give it a go. For very long cruises I want to have the opportunity to make my patrol as long as possible to give me time and distance to intercept long range targets, get home if damaged, etc. So I like to go Ahead Slow at PD from sunrise till midnight. At 0000 hours, I surface to charge batts and reload fish, etc. I dive again at dawn, about 0600 hours. This tactic saves me alot of precious fuel. I'm pretty sure its realistic too, though I wouldn't bet my lifes savings on it.

For shorter Type II North Sea cruises, I use Ahead Standard and 1/3.

[JScones]

Someone (Sailor Steve? jaxa?) created a pretty chart a while ago that mapped cruising speed v distance travelled. I think travelling at 9kts was determined to provide the best efficiency.

[U-Bones]

Haha I'm not sure how many times this has been asked -- but its been alot. Let me give it a go. For very long cruises I want to have the opportunity to make my patrol as long as possible to give me time and distance to intercept long range targets, get home if damaged, etc. So I like to go Ahead Slow at PD from sunrise till midnight. At 0000 hours, I surface to charge batts and reload fish, etc. I dive again at dawn, about 0600 hours. This tactic saves me alot of precious fuel. I'm pretty sure its realistic too, though I wouldn't bet my lifes savings on it.

For shorter Type II North Sea cruises, I use Ahead Standard and 1/3.

You are wise in your betting, and dead on with the ahead slow, but the submerged thing: you would need to max surface time for realistic mileage miser mode.

If this were realistic, everyone would be running generators to charge the batteries their cars run on. Unfortunately, energy is -always- lost when you convert from one form to another.

In game though, it IS more efficient ;)

[Rose]

So you think Ahead Slow on the surface 100% of the time (early war I'm assuming) is the best bet? And JScones, you think 9 knots is best?

[JScones]

I don't know if 9kts is "best", I was just impressed with the chart and analysis undertaken some ways back. It convinced me. I travel at 9kts surfaced all the time. Hopefully someone here with a better memory than me will remember the related thread's contents.

[cobalt]

by running at ahead slow and submerging at night (its mid1942, best tactic for me right now) i can save the fuel reserve for a couple months in a viic

[Sailor Steve]

Someone (Sailor Steve? jaxa?) created a pretty chart a while ago that mapped cruising speed v distance travelled. I think travelling at 9kts was determined to provide the best efficiency.
T'wasn't me. I always go at Ahead 1/3 when travelling. Once at my patrol zone I use Ahead Slow. Curious thing, though: using the NASA Battery Fix I noticed that a Type II can't do more than about 12 hours at Ahead Slow submerged, but if I manually set it for 2 knots it lasts way more than 24 hours.

[Threadfin]

I've done alot of testing, and a setting of just barely above slow is most efficient IMO. Using the navigator to report range you can see it. What I do is set ahead slow, then click the speed dial just barely above the current speed. Let's say ahead slow gives 8 kts. I then click the speed dial on 9kts. The speed stays at 8kts (sounds confusing I know), but the range increases by about 2000km (in type VII with GW engine).

The most efficient speed is also a function of which engine you have installed on your boat I have found.

Test it for your self. Set ahead slow just after leaving port, and run at relatively high compression to give reliable results (no speed change due to wave action etc). Click the navigator and check his range estimate, get several readings to get a good sample.

Now click the speed dial (not the telegraph) maybe a half knot or a full knot over the ahead slow speed and get some more range reports from the navigator. If you results are like mine, your most efficient speed will be just above ahead slow.

Cobalt~ I'm curious why you submerge at night instead of during the daytime? That's opposite of what I might do. Just interested in your reasoning.

[U-Bones]

12 hours @ 2kt submerged = 24kt traveled.

-2kt for ~4 hours charging to fully charge = 8kts less traveled in return for the 24 on battery. Your batteries may charge in more or less, but you get the point. If you are running on fumes, submerge when you are not charging.

[Keelbuster]

I go ahead slow if i'm crossing the ocean. It feels efficient. Ahead 1/3rd feels slightly less efficient. But, I use a Type VII so I rarely have to go that far. If I do, I can cross the atlantic (to the carribean) using about 1/3 of my fuel reserve, giving me 1/3 to mess around and 1/3 to get back. But I wouldn't make the crossing if I didnt' have a Utanker to dock up with. It's just not worth it. For local hunting in the Western approaches, I don't need much fuel. I almost always return with about a half tank - that's with extended searching, and multiple flank overhauls. Fuel just isn't that important. My torps always run out first.

Kb

[Egan]

Haha I'm not sure how many times this has been asked -- but its been alot. Let me give it a go. For very long cruises I want to have the opportunity to make my patrol as long as possible to give me time and distance to intercept long range targets, get home if damaged, etc. So I like to go Ahead Slow at PD from sunrise till midnight. At 0000 hours, I surface to charge batts and reload fish, etc. I dive again at dawn, about 0600 hours. This tactic saves me alot of precious fuel. I'm pretty sure its realistic too, though I wouldn't bet my lifes savings on it.

For shorter Type II North Sea cruises, I use Ahead Standard and 1/3.

Standard practice at least up until later on in the war was for U-boats to travel on the surface as much as possible for a variety of reason. Your speeds are sensible and they are pretty much the ones I use. I sometimes knock the speed down by a couple of knots to simulate running on only one deisel engine which was was fairly common practice in real life but not possible in the game. When I am in my patrol area I tend to travel a 3 or 4 knots. its amazing how much fuel you can save by adjusting the exact speed.

[CCIP]

It's easy to tell what's best, just look at the max distance :p

Unless I'm in a rush, or the patrol is not all that distant, 'slow' is always my speed of choice. I think any Type IX captain should be used to it by now - you need to be able to exploit every inch that boat can travel in far-away waters!

[Rosencrantz]

Egan wrote:

When I am in my patrol area I tend to travel a 3 or 4 knots.


Just thinking that simulating driving with just one diesel by dropping your speed to 4 knots. I'm not totally sure if this is realism if talking about VII or IX boats. Schaeffer (Cmdr of U977) wrote 6 knots was slowest speed ahead VII could go on the surface. It's not mentioned if that was done with one or two diesels, so I just assume he must be talking about using just one engine. (The boat was getting close to Norway coast in the darknes and they wanted drive as slow as possible).

So I think it's very much possible Dev's didn't gave a single thought on that one diesel / two diesel thing at all when adjusting engine orders and speed releated.

Greetings,
-RC-

[robj250]

Wow, I guess I am doing it all wrong then as I run on the surface with my VIIB at ahead standard. So I should be running at ahead slow on the surface?

[Rosencrantz]

Rob wrote:
So I should be running at ahead slow on the surface?

On the oparea and if you are looking for realism, yes. They tried to save fuel as much as possible. They even didn't use "heaters" in the boat for the same reason. Not even in the arctic. That was Dönitz order.

-RC-

[Threadfin]

To maximize range and endurance, yes :)

For me, range is rarely an issue except in long distance IX patrols. Endurance is what I'm after. Either way, running slower is better. And this means you'll have plenty of fuel for high-speed end arounds and interceptions when needed.

[robj250]

To maximize range and endurance, yes :)

For me, range is rarely an issue except in long distance IX patrols. Endurance is what I'm after. Either way, running slower is better. And this means you'll have plenty of fuel for high-speed end arounds and interceptions when needed.

Cool. Well I most certainly would not want to disobey an order from Dönitz. I'll have to tell this to my CE then :rotfl:

[Egan]

Just thinking that simulating driving with just one diesel by dropping your speed to 4 knots....

....So I think it's very much possible Dev's didn't gave a single thought on that one diesel / two diesel thing at all when adjusting engine orders and speed releated.

Greetings,
-RC-
No, your right. I'm in a type 2 over at W@W just now so that has probably coloured my thinking somewhat..Lol. I think it still applies, though. Go to 1/3, ahead slow etc and trim a knot or two off your speed by adjusting it manually. I guess in a 7 I would be patrolling my grid at 5-7 knots.

[Rosencrantz]

Yep. 5 to 7 sound fine for VII.

-RC-

[Redwine]

I use 8 knots in the type VII, wich if i am not wrong is near the real long range speed. I use 10 or 12 knots max only in special situations, in example to pass shallow water zones quickly.

[P_Funk]

I find it interesting how you guys all talk about fuel efficiency and "orders" but anyone ever consider how a U-boat captain would behave if he didn't think the war was worth his crew's lives and so would perhaps behave differently so as to maybe get his men home sooner? For instance recall that scene in Das Boot where the captain fired a torpedo at a stationary tanker that he had already hit to finish it off. If he wanted to milk his patrol for every merchant he could, then he likely would have used the deck gun instead. So then couldn't some Kaleuns have been a little less rigorous in their fuel economy so as to expedite their return to base? I mean if you guys are real hardcore and even try to represent single diesel operation when it isn't modelled shouldn't someone pretend to be looking out for his crew as another layer of the "make-believe"?

[Eichenlaub]

My rig is a type VIIC in mid-'43. I always sail at Ahead Slow to conserve fuel. I also believe my watch crew have a better chance of spotting the enemy while I'm at AS. Furthermore, my sub doesn't produce such a large wake for aircraft to spot (the advent of radar reduces this advantage from 1942 onwards).

At the beginning of my career I usually journeyed at Ahead Standard, but that left me with too little fuel to chase more than a handful of targets. Ran out of fuel once, and didn't want to repeat the embarassment.:oops: Recently, more and more convoys do around 13 knots, meaning I have to crank out a lot of knots over 10+ hour periods to do an end-around. Conserving my fuel pays off.:rock:

On homeward journeys, i.e. when all my ordnance is gone, I often travel at higher speeds since I no longer need to conserve my fuel.

Beginning somewhere in 1942 I order PD at dawn and surface at night. It helps preserve fuel as well, but that is merely a secondary benefit.

Kind regards,

Eichenlaub

[Khayman]

For instance recall that scene in Das Boot where the captain fired a torpedo at a stationary tanker that he had already hit to finish it off. If he wanted to milk his patrol for every merchant he could, then he likely would have used the deck gun instead.

Sinking a ship with the deck gun, even a damaged one, could take an hour or more. Using the deck gun was only permitted in safe waters, where there was no risk of the U-boat being surprised by aircraft or enemy vessels. Therefore using an extra torp to finish off a ship was common and wasn't a way for the Commander to bring his boat home earlier.

So then couldn't some Kaleuns have been a little less rigorous in their fuel economy so as to expedite their return to base?

Since every Commander had to report to Donitz after his patrol, and their patrol was examined in minute detail, then I doubt anyone could have gotten away with it. This also applies to using too many torpedoes on a single target. I think they would rather risk death at sea than face the wrath of the B.D.U.

As for me, I use U-123's Drumbeat patrol as a guide. Hardegen wrote in his KTB: "Total distance: 8,277 nautical miles. Total submerged: 256". Besides it was only advisable to submerge if the weather was bad, or if there was a danger of aircraft. The U-boats place was on the surface at all other times. For speed I use 9 knots, but only because I read it here! I did try going to the US at 4 knots on the surface, but it was a disaster fuel wise.

[Sailor Steve]

If I've had a good patrol and am out of torpedoes with sufficient fuel remaining, then yes I'll head home at a faster speed, if I'm sure I can make it safely.

[Keelbuster]

If I've had a good patrol and am out of torpedoes with sufficient fuel remaining, then yes I'll head home at a faster speed, if I'm sure I can make it safely.

Me too. Especially crossing Biscay. I'll do it at ahead full, and storm into port at flank.

Kb

[robj250]

If I've had a good patrol and am out of torpedoes with sufficient fuel remaining, then yes I'll head home at a faster speed, if I'm sure I can make it safely.

Hey Steve, just curious. How many patrols have you completed and what year are you in now?

[Sailor Steve]

Hey Steve, just curious. How many patrols have you completed and what year are you in now?
I got the game about a month after it came out (actually had the game from day one but had to wait for a computer that would run it).

I'm not sure how many patrols I've completed, but it's a lot. I've never completed a career, though. Back in the SHI days I got into the habit of running several careers simultaneously-one from each available base. If a captain died or retired, I'd start a new career that same month from the same base. With the wonderful facility from Beery's Flotilla Mod and SH3 Commander I can do the same thing with SHIII. Unfortunately things keep happening: I'll experiment with a mod and not like something, switch back in mid-patrol without thinking, thus ruining that career.

So I go back and start over. Currently I'm helping with some mods and experimenting with my own, so I'm waiting to start over again. The farthest I've ever gotten was June 1940. Those patrols were recorded here:
http://www.subsim.com/radioroom/showthread.php?t=88004&highlight=sailor+steve%27s+patrol+logs

[robj250]

Thanks for posting the link to your patrols. My patrols are probably too boring with too much detail. Have a look and left me know what you think. The link to my patrols is the blue link below my signature.

[Ducimus]

So then couldn't some Kaleuns have been a little less rigorous in their fuel economy so as to expedite their return to base?


No.

Fuel is life, and should be conserved whenever possible.

Reasons to conserve fuel:
- Incase you have to do a high speed dash to run away from something.
- Incase you have to do a high speed dash to intercept something.
- Incase your fuel bunkers are damaged for whatever reason. (this has happned to me before)
-Lastly, and most importantly, to make sure you can get home.


More then once, ive sputtered into lorient harbor, with the CE saying the fuel reserves are empty, and the NA estimating we can go 400 KM on what diesal fumes remain.

[Highbury]

I find it interesting how you guys all talk about fuel efficiency and "orders" but anyone ever consider how a U-boat captain would behave if he didn't think the war was worth his crew's lives and so would perhaps behave differently so as to maybe get his men home sooner? For instance recall that scene in Das Boot where the captain fired a torpedo at a stationary tanker that he had already hit to finish it off. If he wanted to milk his patrol for every merchant he could, then he likely would have used the deck gun instead. So then couldn't some Kaleuns have been a little less rigorous in their fuel economy so as to expedite their return to base? I mean if you guys are real hardcore and even try to represent single diesel operation when it isn't modelled shouldn't someone pretend to be looking out for his crew as another layer of the "make-believe"?

You will also recall the Navigator telling him "we are just burning fuel" by staying on the surface in rough weather. Not just the Kaleun, but on the whole the entire crew wanted to save fuel when they could. I am sure in that particular movie though the Chief would have been dumping it over the side if he could.

As for in game I usually run 9 - 10 knots. Although not too accurate, the navigator's estimate of range at current speed ALWAYS shows much, much longer range at 1/3 then at ahead slow. I have found that in the Type IIs and VIIs anyways. I rarely use ahead slow on the surface for anything. Wastes fuel IMO.

[Ducimus]

Personnly i think fuel management is a crucial issue for an IX boat.

As it happends with "ahead slow", with the MAN supercharger, you cruise just under 9 kts, which is the speed alot of ppl recommend.

But again, fuel, your use of it is crucial. I break fuel down in a few ways.

1.) Fuel used to get to, and leave patrol area. This acutally makes up the bulk of my fuel expenditure.

What you have left is.

2.) Fuel used while in your patrol area. This acutally is a small fraction of the fuel that you use, and this fuel is the most precious if you want to make the most of your patrol. High speed pursuits cuts into your ablity to loiter in your patrol area. Often ill cruise at 5 kts while recharging batteris, and will remain submerged during daylight hours to not burn any diesal.

The thing is, diesal usage, im almost positive is based on how many RPMs the engines are turning. Recharing batts, you have one enging running at 500RPM.s (thats FLANK), the other engine propells the boat, which is why ill go to 4 or 5kts whiel recharging bats to lower the RPM's - which in theory, lowers the fuel usage for that engine.

Usualy for me, around 50% fuel means its time to return to port. No if's, and's, or buts about it. To get the the caribean for lorient, ill have used, on the average, around 40 to 45% of my fuel reserves. Which give me around 15% reserves fuel that i acutally operate on.

[U-Bones]

I thought some of you would appreciate this.

I did a test on a VIIB w/stock engines last night in search of the setting I want to use in NYGM 2.0 and created a table at

http://members.bellatlantic.net/~vze33y78/VIIspeed.htm

My criteria for selecting what I did was:

1. Ahead slow needs to be slow enough for Silent running to be silent, or < 2.0kt. I was tired of doing it manually. Surfaced it just need to be enough to provide steerage.

2. Ahead standard simply needed to be the most efficient speed surfaced.

3. Ahead 1/3 needed to be fast enough for quiet depth changes submerged or > 1.9kt. Surface just needed to be "no wake" speed. It was a nice bonus that it turned out to be exactly 1/3 of Full throttle.

4. Full - exactly double standard, or military time, double time.

5. 100%

I did not test charging times for non selected speeds because it was not a selection criteria.

[Sailor Steve]

Thanks for posting the link to your patrols. My patrols are probably too boring with too much detail. Have a look and left me know what you think. The link to my patrols is the blue link below my signature.
"Too boring with too much detail." That's what a lot of folks said about mine. I like yours fine. The only suggestion I would make is spacing between separate events, or at least between days. I thought they made good reading, though.

[Rosencrantz]

In a way P-Funk is right. I sure nobody here is playing with too tight rules, without any space for a common sense. If one is telling, he use to drive 6 knots, I think this usually means he drives 6 knots when on oparea (talking about VII boat). My basics are these:

- Approach marsch to the oparea: Any speed between 6 - 15 knots depending on the weather and situation overall. Usually making about 10 - 12 knots, on the narrow / shallow waters, especially when the contact with the enemy is highly possible - 15 knots or more if possible due the sea state.
- On oparea: All ahead slow, about 6 knots. If in rough weather, I use to order engines to make couple extra knots. I'm not sure if this is realistic, but I think it could be. (More power to make it easier for the helm to keep the boat on the track, for example)
- Inbound marsch back to the base: Only rule for me is to do that as quick as possible.


-RC-

[Ducimus]

Bah, you type 7 skippers have it easy! Your in spitting distance of your AO the instant you leave biscay bay!


If i sprinted back to base as fast as possible, i woudlnt make it back to base at all.


Seriously, if you wanted to cut short a patrol, all you have to do, is say, "I am low on provisions". Food provisions is not modeled in this game, realistically your ablity to stay at sea is dependant on 3 things i think:

-Fuel
-food
-Health of the crew.


If you have crewmembers coming down with skurvy, its probably time to go back to port. if your running low on food, its probably time to go back to port.

You dont need fuel as an excuse to cut short a patrol.

[Rosencrantz]

Ducimus wrote:

Bah, you type 7 skippers have it easy!


Well, dear Ducimus, don't look at me when saying that. I usually play with IX. Just using the VII as an example, because I think that's a most common boat type between the simmers - just as it was in the RL. :p

-RC-

[robj250]

"Too boring with too much detail." That's what a lot of folks said about mine. I like yours fine. The only suggestion I would make is spacing between separate events, or at least between days. I thought they made good reading, though.

Thanks. I will do that.

[Ducimus]

Ducimus wrote:

Bah, you type 7 skippers have it easy!


Well, dear Ducimus, don't look at me when saying that. I usually play with IX. Just using the VII as an example, because I think that's a most common boat type between the simmers - just as it was in the RL. :p

-RC-


Im just funnin'. Nothing wrong with a little friendly competition. :lol:
But seriously, fuel i dont think is as much of an issue if your using a typ7 because more ofthen then not, you dont have to travel anywhere near the length you would if you were in a type 9 in the 2nd or 10th flotilla.

I can't think of a better example then any grid assigment that starts with GR.

Getting back to port quickly isnt an issue, making sure you have enough fuel to get back to port AT ALL, is. You get home when you get home, however long it takes, but if you run out of fuel, your done.

[Keelbuster]

If I remember right (under all that rum) then it took me about 1/3rd of my VIIB fuel to get over to halifax at ahead slow (9kts/MAN). That give plenty to hunt. If you want to go to the carribean, you need a utanker.

Kb

[Ducimus]

How much fuel you use (percentage wise) depends alot on the range vs speed if your running any modded sub filesn.
To the point, if your edit your sub files, theres a big difference between:

13,450 KM @ 10 kts
and
13,450KM @ 12 kts.


@12 kits gives you ALOT more fuel then you what you probably should have. To be honest ive fudged it a little and have been using " @10.75 " kts which gives me a tinsy bit more fuel while not straying too far from historical statistics very much.

[Rosencrantz]

Ducimus wrote:

But seriously, fuel i dont think is as much of an issue if your using a typ7 because more ofthen then not, you dont have to travel anywhere near the length you would if you were in a type 9 in the 2nd or 10th flotilla.



That's true I think. I still remember my first IX drive: I left Kiel in the summer 1940 and because the weather was good, I let the boat run 14 - 15 knots over the North Sea and those narrow waters north fm Scotland. When I reached the Atlantic I was surprised how much I got fuel allready used in the fast driving. But it was time to slow down anyway. The oparea was somewhere in the central Atlantic, near Biscaya, so no problem comming back. It's a pitty there is not much friendly units on the sea you could ask to help you out, if you run low on fuel. Think if if you could send a message to BdU which then sends you a AI combat sub to give few more tons. Like it was in RL. One feature I would like to see in the coming SHIV.

-RC-