Question submarine range

[Archer7seven]

Ahoy mates.

I'm a fan of cruiser submarines and play mostly with the Donation Narwahl. My base in Brisbane and I stop at Tulagi to refuel, but even then, with an objective that has a roundtrip of about 7K nautical miles, I barely make it back to base.

Most of the time is spend submerged, surfacing only to recharge the batteries and to attack.

The boat is supposed to have a surface range of 10KNM.

m running TOM 2.5 along with the Donation Narwahl, the greatest range indication that I have ever seen was just over 7K NM, with flat seas on slow ahead.

Can this range be adjusted in the coding?

Thank you.

[c13Garrison]

Greetings Archer! I also use the donation Narwhal, and I find I have an enormous range. The most economical transit speed is 2/3s on the surface, and it should be over 11k. Running submerged is your problem. Recharging batterues uses fuel like you were running at full speed.

I recommend only running submerged during the day if air contacts are so frequent diving becomes irritating. At 2/3s submerged speed you should cruise at 4 knots for 14 or 15 hours. At night always stay surfaced, unless the weather is so bad you fear blundering into something in the fog (pre radar).

Good luck, and share some war-stories! :up:

[Bubblehead1980]

Ahoy mates.

I'm a fan of cruiser submarines and play mostly with the Donation Narwahl. My base in Brisbane and I stop at Tulagi to refuel, but even then, with an objective that has a roundtrip of about 7K nautical miles, I barely make it back to base.

Most of the time is spend submerged, surfacing only to recharge the batteries and to attack.

The boat is supposed to have a surface range of 10KNM.

m running TOM 2.5 along with the Donation Narwahl, the greatest range indication that I have ever seen was just over 7K NM, with flat seas on slow ahead.

Can this range be adjusted in the coding?

Thank you.

Ahead slow is not the most economical fuel setting usually.Ahead Standard is supposed to be the most fuel efficient speed in TMO. Use the range calculation button under the navigator tools to figure out different ranges at different speeds.Staying submerged most of the day and recharging every night also burns up fuel as it takes extra power from engines to charge batteries and thus burns fuel.

Keep in mind Narwhal class were old and fuel hogs, various factors affected range etc.

[Sailor Steve]

Also be aware that running submerged and only surfacing to recharge is the worst thing you can do. You may be going slow but the engines doing the recharging are running at flank speed the whole time.

Yes, the ranges can be adjusted, but if you follow Bubblehead's advice on running in TMO you should be good to go. :sunny:

[c13Garrison]

I believe my info to be correct, but I must assume I am in error. Forgive me for failing to give accurate advice.

[Admiral Halsey]

Ahead slow is not the most economical fuel setting usually.Ahead Standard is supposed to be the most fuel efficient speed in TMO. Use the range calculation button under the navigator tools to figure out different ranges at different speeds.Staying submerged most of the day and recharging every night also burns up fuel as it takes extra power from engines to charge batteries and thus burns fuel.

Keep in mind Narwhal class were old and fuel hogs, various factors affected range etc.

While Ahead Standard is supposed to be the most economical Ahead 2/3s is still the best speed setting. Also you should manually adjust the Narwhal to 8 knots as that is the most economical speed for it.

[Archer7seven]

Many thanks.

I shall try that.

[Bubblehead1980]

Okay when say economical also including the rate of advance.For example, sure in a Gato or Balao 10 knot transit will use less fuel than ahead standard 15.5 knots.The thing is, transiting the pacific at 10 knots is tantamount to harbor speed.Unlike in real life, we dont have to worry about crew morale that much or food supplies, fresh water etc. Generally, subs transited to and from their areas at standard speed, slowed to patrol, depending on where they were.In the game, I transit to and from area at ahead standard, patrol at 2/3(actually adjust it down to 9 1/2 knots) to squeeze a few extra days on station.There are times if patrol area is far off, I may transit at say 12.5 knots in lieu of 15, saves some fuel.Each class has its own tricks.

The older boats standard speed may be less but it was the most efficient as well.The stock game did not reflect this, ducimus fixed this in TMO(RFB did also I believe). I havent used the Narwhal that much but never had the fuel use problems several have reported when I did.Simply use the navigator to give a range estimate at current speed, adjust speed as needed.

[Rockin Robbins]

The important thing is to remain on the surface every second you can. The number of contacts you develop is proportional to the number of square miles you search in a day. And you have to be able to fight your boat. That means your batteries should be fully charged when you enter combat. After all, you don't know how long escorts might keep you down.

But the worst thing about running around with batteries not fully charged is that while charging your diesels run wide freaking open until you're at full change. There goes any decent range! Every minute you don't have fully charged batteries subtracts lotsa minutes on station.

[TorpX]

Part of the problem may be the speed you are using. Unneccessary speed used is fuel wasted. The V-boats should have plenty of fuel for an extended patrol. (If not, the mod is not a very accurate representation.) There is no particular advantage to going fast, if you are just patroling. This applies to both submerged and surfaced patroling, but especially to submerged patroling. If circumstances are such that you decide to patrol submerged during the day, that is ok, but do so at minimum speed, say 1.5 to 2.5 knots. This will reduce the amount of fuel used in battery recharging.

[Sailor Steve]

A part of the problem with any discussion of range is that no one who was there ever seems to give actual ranges. Without going into a detailed discussion of hydrodynamic drag it can be simply said that drag increases as the cube of the speed. It takes 1000 times as much horsepower for any ship to make 10 knots as it does to make 1 knot. At 15 knots you're using 3375 as much power as you were at 1 knot. That's more than 3 times the horsepower required to cruise at 15 knots than at 10 knots. does that equate to 3 times the fuel consumption and 1/3 the range? I don't know, and I admit it does sound extreme.

By that calculation a ship is using 9261 times as much power at 21 knots as it was at 1 knot. If a Gato class submarine makes 21 knots at 5400 horsepower then it only needs 1970 horsepower to cruise at 15 knots and 580 horsepower to cruise at 10 knots, again just over 3 times the power. On the other hand Dick O'Kane says that they cruised at 80% power, which would be 4320 hp, which by the relative drag calculation would give 16.3 knots.

But there's another problem. The Gato's range is listed variously as 11,000 nm, 11,800 nm and 12,000 nm at 10 knots. Even at the 12,000 mile range that makes for a patrol of 50 days, and the Gato is also listed as carrying fuel for 75-day patrols. At 10 knots that's 18,000 nm, not 12,000. Even if 15 knots required twice the fuel that would still give a 9000-mile range.

Without actual reports of how fast they cruised it's impossible to know what the reality was.

What is the game reality? Go different speeds and check the estimated range at those speeds.

If you have the patience here is an old discussion on the subject which I found informative and enlightening, even if in the end there is still nothing truly conclusive.
http://warships1discussionboards.yuku.com/topic/19783/US-WW2-Fleet-Boats-vs-German-Type-IX-Range

[BigWalleye]

Dick O'Kane has a couple of discussions of range versus cruising speed, but nothing very quantitative. I suspect the information is all available in the patrol reports online at http://hnsa.org/doc/subreports.htm, if anyone were determined enough to mine that information. But, of course, that still wouldn't reflect our "reality", which is what is actually programmed into the game. Probably best is to keep aware of the current fuel situation using the Navigator reports, keep a Bingo reserve (RTB plus 10% of cruise range), and not use any arbitrary rule or speed setting. As skipper, you are responsible for getting the boat back to port, not the Navigator, not the game designers, not the software. That responsibility is part of the simulation. Ignore it and you won't die, your crew won't die, but you may lose a distinguished career.

[Rockin Robbins]

Regardless of how many miles the range is, the secret to having plenty of fuel is to be on the surface at 9 knots every second you can. Be submerged for the absolute minimum amount of time. That means no underwater daytime patrols. When you are underwater it means you were forced there because your life depends on it, not just in theory, but immediate deadly danger.

[TorpX]

I read the discussion you linked to. Very interesting, but as you said, hard to draw any conclusions from it.



On the other hand Dick O'Kane says that they cruised at 80% power, which would be 4320 hp, which by the relative drag calculation would give 16.3 knots.

But there's another problem. The Gato's range is listed variously as 11,000 nm, 11,800 nm and 12,000 nm at 10 knots. Even at the 12,000 mile range that makes for a patrol of 50 days, and the Gato is also listed as carrying fuel for 75-day patrols. At 10 knots that's 18,000 nm, not 12,000. Even if 15 knots required twice the fuel that would still give a 9000-mile range.


IIRC, O'Kane mentions using 80% power, but I don't believe he meant that they cruised with all engines. Most of the time they would cruise on 3 or maybe even 2 engines. Running them at 80% allowed for good fuel effeciency, without putting undue strain on the engines.

The 75 day patrol endurance, I think, refers to the supply stock. I would not expect that they actually contemplated continous cruising at 10 kts.

Without actual reports of how fast they cruised it's impossible to know what the reality was.


Agreed, it is very hard to pin down the numbers in these things.