5 or 10 meter. Makes a difference?

[vincentz]

Just a quick question.

Does the game take into account if you "dive" to 10 meter instead of the standard 5 meter surface, meaning : will you be less visible and therefore less detectable diving to 10 meter (and still be able to use TBT/Radio, standing on the bridge etc) or has the game 2 settings to calculate detection from (surface or submerged)?

[Rockin Robbins]

Yes, when I am at decks awash (about 32' on a Gato or later boat) I can get much closer to a target without detection than when I am on the surface. Your speed also makes a difference. Staying below 10 knots is a must. That's not a problem at decks awash because you can't go any faster!

[vincentz]

makes sense. I just didn't know if it was programmed to spot the difference.
I love the game, but it has soooo many flaws and bugs that it wouldn't surprise me if either the game counted it as "fully visible" at 10 meters OR "fully submerged". I hope its in the middle.

[Armistead]

People argue what decks awash is in game, to me it's only diving deep enough, but engines are still running. If you dive deep enough, your electrics will engage and watch crew vanish, yes, you can still roam the bridge, but in all aspects the game views you as dived and you are now a target for sonar. To be it's a cheat to do decks awash when your sub is technically dived.

[Rockin Robbins]

In reality, there were two decks awash procedures. One was to leave the diesels running, the other was to be a bit deeper and use electric motors.

We can do both in the game. Like you I like to be decks awash with diesels running. My most urgent need is have fully charged batteries at all times. This reduces fuel use and gives me a fully combat ready submarine that can remain submerged for the longest possible time if it is necessary for survival.

There have been limited numbers of times where I came to the surface for thirty seconds or so to get a radar fix. Then I will typically come to 37 feet or so, get the fix and submerge again. In this case the important thing is to keep visual signature as small as possible. Since I came from an environment where I could be detected on sonar, it doesn't matter that I still can be as I pop up for a peek.

[Daniel Prates]

RR, you're talking RL procedures, or game procedures only? Or RL skippers would indeed often use decks awash tactics?

[Rockin Robbins]

Both. They ran decks awash almost all the times during night surface attacks. Even during the daytime, if they anticipated needing to dive quickly they would limit the amount of freeboard so they had less of a ballast tank to fill to get to negative buoyancy.

My specific comments were about game conduct though.

[TorpX]

I've never used the "decks awash" proceedure in the game, so I don't know how that works, but it strikes me as a gamey tactic. I can't really see how lowering your depth a few feet changes your profile much or makes you harder to spot at night. In this sort of situation, you would be spotted by the phospheressence of the water or the silhouette of your tower against the night sky. Neither of these would be changed much by running decks awash. What would change would be that you would have tons of extra weight (and greater draft) slowing you down. Maybe I'm wrong, but I can't recall ever reading of this tactic being used. I can see using electric motors on the surface, in order to be quiet, but this is not quite the same thing.

I did read of the Pompano (and two other subs) doing the opposite on Dec. 7th '41. By this I mean they were running with all ballast empty (even the safety tank), in order to obtain the best speed and keep their schedule. After the news of the air raid on Pearl Harbor was transmitted, this was realised to be a mistake and they immediately compensated the boat and rigged for dive.

[Sailor Steve]

No one ever travelled in a decks awash condition. As you point out, it causes complications with drag and fuel usage. What is being said is that it was used a lot for night surface attacks. You want to be moving slowly to keep wake and phosphorescence down, and the lower profile helps when approaching enemy shipping, and you're already at or near neutral bouyancy which helps you get down faster if you are spotted.

The game doesn't reflect the procedure properly. I'm pretty sure that most decks-awash attacks were conducted on battery power, to help keep noise down. In the game that automatically makes you 'submerged', so the watch crew disappears. The lowered 'surface' depth is the only compromise available.

[Rockin Robbins]

What!!!!???? No one ever used decks awash in real life!!!!????? Gamey????!!!! WTF!!!!! (that seems to be a trendy expression around here lately, just getting with the program.....:D)

Decks awash is a VERY useful thing in real life for limiting the profile and visibility of the sub and was used extensively both by the Americans and Germans. Both groups of captains thought that lowering the profile by fifteen feet was meaningful and useful.

Yes, being heavier made no difference in speed, it would have slowed acceleration, but its most important effect was that the MBT already had lots of water in it. And negative was flooded, giving the sub instant negative buoyancy when they opened the top vents. In decks awash the lower vents were already open to let water in and only air pressure in the tank kept more from entering. What slowed the boats down, and that is replicated in SH4 is the increased wetted surface of the hull. With a Balao it's impossible to go more than 10 knots decks awash. That's good because above 10 knots the enemy spots you from a much greater range.

When you are fully surfaced, not only is your profile 15' higher, but you have to let thousands of gallons of water into the ballast tanks in order to submerge. You can cut your submergence time by more than 50% by running decks awash and believe me they did it a lot in the war.

It's a shame that we can't change from electric to diesel power. There were times when the real boats did that even when fully surfaced. We should be able to also. We also only have the choice of going to full charge batteries or normal running. We should be able to select which engines will drive and which will charge, as the real captains did.

When you're out on the ocean, there is phosphorescence everywhere due to wave action. Unless you were leaving a wake at high speed, in most circumstances you would not have to worry about phosphorescence being visible around the boat.

If it were calm, you would even have to worry about phosphorescence from disturbed surface water if you were at periscope depth and for some depth below that. It was normal procedure to submerge to 150 feet or so to do a high speed underwater run, partly for that very purpose. Of course, SH does not replicate that effect.

[Daniel Prates]

My specific comments were about game conduct though.

Yeah that's what I was asking. It seems to me that there is no compairson between game and actual conditions, and as Steve pointed out, what we have is the "lowered surface depth" in-between solution.

[Sailor Steve]

What!!!!???? No one ever used decks awash in real life!!!!?????
I hope that first one wasn't aimed at me. I was pointing out that they didn't travel decks awash, nothing else. It was used all the time for night approaches and attacks.

[TorpX]

I'm sure it was aimed at me. :)


I still don't see any advantage to it. Submarines are designed so they are low in the water. It would be very difficult to spot one on a dark night. Observers would have to be able to see a dark object smaller than their own vessel, on the surface of dark water. They would be looking 'down' and this would make the task more difficult. There being little contrast between the dark water and the dark hull. Unless one could submerge the boat enough to totally cover the hull (a very dubious proposition), what would be the point?

O'Kane and Fluckey made very daring night surface attacks, but say nothing about moving about half submerged. They do talk about evading on the surface at high speed however.



When you are fully surfaced, not only is your profile 15' higher, but you have to let thousands of gallons of water into the ballast tanks in order to submerge. You can cut your submergence time by more than 50% by running decks awash and believe me they did it a lot in the war.



I don't want to get into a long drawn out and pointless internet argument, but could you provide one or two examples?

[Sailor Steve]

I only have a couple, but the term itself was common enough that at least one old submariner named his website Decks Awash. Also the term was used as a movie title, which proves nothing but certainly shows that they were familiar with the term. On the other hand the term is also used for a sinking ship that is still barely afloat.

I only have one example at the moment.
Scott ordered the submarine trimmed down to awash conditions to reduce her silhouette, and put her on four engine speed to pull ahead of the convoy. At 2237 the convoy changed course to 085 degrees T, which placed the submarine dead ahead. Scott slowwed Tunny to two-thirds speed and headed in to attack with decks awash.
-Theodore Roscoe, United States Submarine Operations In World War Two, page 257

[Rockin Robbins]

Some examples:

Page 46 of the USN Lookout Manual, NavPers 170069 (http://www.ibiblio.org/hyperwar/USN/ref/Lookouts/index.html#S10) contains a statement that a flooded down submarine can submerge "in a matter of seconds"
http://en.wikipedia.org/wiki/File:HMS_B11_Under_way_decks_awash.JPG A photo of HMS B11 underway with decks awash

http://www.submarinesailor.com/stories/DecksAwash.htm a humorous account of a submarine running decks awash to clear a lowered drawbridge to get home quickly

http://www.valoratsea.com/glossary.htm#F glossary item for "flood down" wouldn't exist unless it was a practice in submarines.

There are lots of anti-submarine air patrol reports of encountering enemy subs flooded down, running decks awash. Just a couple, the second link contains two separate incidents, indicating that it was COMMON to find U-Boats in a decks awash condition. http://www.uboatarchive.net/U-569-8-Analysis.htm and http://www.destroyers.org/histories/h-dd-648.htm and http://www.uboatarchive.net/U-615ASW-6Crockett.htm there are plenty more.

I'm away from my book collection at home and can't find any US Sub Commander's personal reports. You'll have to take my word they exist.

Finally, a VERY interesting observation from Paul Wittmer over at the Subvetpaul website, an authority to be reckoned with. He indicates that at decks awash the sub was severely lacking in roll stability and that the tactic could only be used in mild weather. Note that he was NOT a sub commander and can only testify according to information collected from boats on which he served. http://www.subvetpaul.com/Flt_Class_Sub.html.

He says "The metacenter is a point where the center of gravity of the boat coincides with the center of buoyancy; a very hazardous point which must be passed quickly. If the center of gravity and the center of buoyancy are coincident and if a wave were to hit the boat from the side, capsizing could occur. Those Hollywood movies where a submarine is shown with decks awash, making an approach on the surface is mostly fiction. That is about where the two centers become coincident and it doesn't take much to roll the boat over. "

It's an interesting point, but his conclusion that decks awash was a seldom used condition is contradicted by the other evidence.

Obviously, many things that are unsafe in peacetime are perfectly normal in the course of war, like "riding the vents" where the bottom vents are always open and ballast tanks are only prevented from flooding by air pressure restrained by the top vents. By not using the bottom vents, subs could dive ten seconds or so quicker. Every submarine rode the vents just about all the time during the war. Opening the bottom vents is MUCH quicker than filling the MBT the third of the way or so for a decks awash condition. Everyone who thinks a sub captain would NOT want to save that amount of time in a crash dive to avoid a plane or shells from a nearby escort, raise your hands!:D

[Armistead]

One of the pains in the game, moreso with mods like TMO is it's very difficult to pull off a night surface attack, but it can be done. The problem is getting close enough, say 2000 yards, the bigger problem is once you attack you get spotted and have to dive or get blasted, so why not dive anyway. The issue is often you have to turn and run and once you get broadside they usually get a visual on you.

I find the better tactic is to setup decks awash or surfaced with the right conditions with stern attacks from about 2000 yards, that way I can just run away. I can put plenty of distance by the time escorts come and why they're searching where my torps came from I can then go in bow making another surface attack and run again, keep repeating until targets destroyed.

Later war when the enemy has escorts I will often shoot decks awash dived enough where engines still run, depending on the mod and radar height values they can't pick me up. However, I prefer being totally surfaced attacking as I said above.

[TorpX]

Sailor Steve and Sailor Steve:

OK. You have presented very good evidence. I'll concede it was a commonly used tactic. Still seems a bit odd to me, though.



He says "The metacenter is a point where the center of gravity of the boat coincides with the center of buoyancy; a very hazardous point which must be passed quickly. If the center of gravity and the center of buoyancy are coincident and if a wave were to hit the boat from the side, capsizing could occur. Those Hollywood movies where a submarine is shown with decks awash, making an approach on the surface is mostly fiction. That is about where the two centers become coincident and it doesn't take much to roll the boat over. "



O'Kane said much the same thing, which is one of the reasons I had my doubts.

I wonder how much they trimmed down their boats and how much speed they lost? :hmmm:


One of the pains in the game, moreso with mods like TMO is it's very difficult to pull off a night surface attack, but it can be done. The problem is getting close enough.............

I agree. Night attacks seem tricky. I may try some of your 'decks awash' methods next time I'm in that situation.

[Sailor Steve]

Sailor Steve and Sailor Steve:
Both of me, eh? :O:

I wonder how much they trimmed down their boats and how much speed they lost? :hmmm:
As I said (and I could be wrong), it's my understanding that it was used for stealth during an attack, and they didn't normally cruise the Pacific in that condition.

[TorpX]

Both of me, eh? :O:


Er, I meant Sailor Steve and Rockin Robbins.


As I said (and I could be wrong), it's my understanding that it was used for stealth during an attack, and they didn't normally cruise the Pacific in that condition.


Yeah, I get that, but in the cases I recall, the Captains wanted to be able to move FAST, when the fireworks started. Remember, we had a discussion about how (or if) a fleetboat was able to move at 22 knots (or 23, or whatever it was).

[Rockin Robbins]

Good point. After sneaking in on my first approach with decks awash to 2000 yards or so, I fire undetected but immediately surface, turn tail and run at high speed. Ususally that results in the escorts doing a pretty perfunctory job of giving half-hearted chase while I get away to end around to the other side of the convoy.

So shoot, helm hard over while the torps are on the way to target. When the boom happens, surface and turn tail at high speed. That's the program on this boat. A boom is a detection and decks awash ceases to be an advantage.:D

[TorpX]

What I've done in the past is either cut into the target's track and count on my narrow profile to keep me hidden, or come in on the surface, but submerge before I get too close. In the former case I would not turn away until the torps hit or just before, lest the target see me and evades the attack. (Ships are really way too maneuverable in this game.)

However, I haven't really made enough attacks to have a "standard" proceedure.

[scubamatt]

For me, making a surface attack usually happens only if I must run on the surface to get into attack range - I encounter a ship moving at medium or fast speed, where I have no chance of getting into an optimum firing position if I submerge.

Decks awash is the best compromise I can make in that case. I run flat out on the surface, getting as close as I dare (this is the point where I catch myself holding my breath in real life). Then it's set my depth at 25 feet (Sargo class), go decks awash and get even closer.

If I'm spotted, I can crash dive fast and evade because the sub is already flooded down. If I'm not spotted I can take my shots, then turn aside and motor away. Like RR said, once something explodes, all bets are off. I figure everyone is looking at me and it's time to beat feet. Surface and sprint (if no close gun threat) or sink like a stone and rig for silent running.

NOTE FOR NEW CAPTAINS: If you've never done the 'decks awash' thing, try doing a crash dive while using time compression. Watch the depth gauge and see how it goes down, then back up a bit and then down..slowly at first...then suddenly plummets. Now surface and do the same thing again, only start from a depth of 25 feet or so (depends on your type of sub). Notice how much faster you are able to get under. Decks awash is also handy if you absolutely must come up for fresh air while there is a serious risk of detection. Come up slowly until you're able to flush your air system (usually a tiny bit deeper than your flooded down depth). You get rid of the CO2 in your boat, but only expose the absolute minimum of your sub to do so. (I don't know if it's TMOwTw or stock, but there is a specific sound effect that sounds like blowers/air rushing when I'm flushing the CO2, and that's my cue that I'm at the correct depth. The CO2 level drops a second or two later.)

[jcope]

I would like to be able to use the external cam on a few tests to get a feel for how visible I really am in various conditions. I wish there was a way to go to a distant position, pull out binoculars and do try to see the sub. I often wonder whether I'm not spotted because of crew inexperience on the enemy's part or because the sub is really that hard to see.

I will definitely practice the decks awash technique. But it would be good to have a feel for how close to be when it becomes necessary, and when you're too close to even be that exposed.

I have yet to make a surface attack, except an early war shot at some docked ships.

[Sailor Steve]

I would like to be able to use the external cam on a few tests to get a feel for how visible I really am in various conditions. I wish there was a way to go to a distant position, pull out binoculars and do try to see the sub. I often wonder whether I'm not spotted because of crew inexperience on the enemy's part or because the sub is really that hard to see.
The problem with that idea is that it is after all only a computer simulation. What you could see is what the computer renders on the screen. What the enemy can see is what the computer tells them they can see. This has been show countless times by players complaining that their watch crew spots a ship but they can't see it, or by the opposite - they can see a ship plainly but complain that the watch crew must be blind. Likewise the sonar - you can hear things the soundman can't, because of the way the program translates things to the screen or the speakers.

The only way going to the enemy ship and looking through his binoculars could work is if the program is adjusted perfectly so that what you see and what the AI sees is the same. As far as I know they haven't been identical yet, in any of the games.

[jcope]

I agree. But it would still be better information than I have now. I think having a rough idea of where I should start worrying about being visible couldn't hurt. Conditions and AI variability can be accounted for as well.

Real life captains must have been able to observe other subs at sea, and must have had feel for how easy to spot they were.

[scubamatt]

Well you can always pick an enemy harbor and sneak up to it during the day. Pick one without a roving guard ship, like the one on the north east coast of Formosa. You want something that has patrol boats sitting around doing nothing. Unless they detect you, they don't start shooting or move from their spots, so they are a great way to test your visibility.

Move up to it (submerged) until you are about 10nm away. Save your game at this point, so you have the same starting conditions each time.

Surface, then motor straight forward at about 2-3 knots, plain as day. When they finally spot you, make a note of how close you got.

Reload and do it again, only this time set your depth at the decks awash setting. You should be able to get closer before they see you.

Reload and do it again at periscope depth, with your attack scope up and visible.

Then you can compress time and try it again at night if you like. You should see a difference between each method.

(Edit: You can also use an enemy fishing boat/sampan to check this. The next time you encounter one, save your game then try going straight at him surfaced/decks awash/periscope depth. Note the point at which he freaks out and starts making frantic turns to avoid you, then reload and check a different method.)

[CapnScurvy]

I would like to be able to use the external cam on a few tests to get a feel for how visible I really am in various conditions. I wish there was a way to go to a distant position, pull out binoculars and do try to see the sub. I often wonder whether I'm not spotted because of crew inexperience on the enemy's part or because the sub is really that hard to see.


A few months ago I set up a test mission with several enemy warships at different ranges around an submerged sub. Actually I had saved two identical test setups, one in daylight, the other at night. I reworked the stock "AI_Sensors.dat" file to only have one particular sensor working at a time (its tough to know what exactly detected the sub in certain conditions). My tests were to just work on the subs detection with visual AI. One during the day, the other at night, and eliminating the other possible sensors detection capabilities. I documented the amount of time it took for an enemy ship to detect the sub with a partial periscope rise; a full periscope rise; a partial sub surfaced position (decks awash); and a full surfaced position. I took into account various distances that were between the sub and target ships and attempted to see when an enemy could detect the sub, and when it couldn't. The seas were calm to remove any "Wave Factor" multiplier.

I found some surprising things.

Specific to the visual detection, I found the "Light Factor" actually is backwards to what it should be. In other words, the higher the "Light Factor" figure, the easier it is for the AI to detect the sub at night. Dropping the figure helped in preventing night detection, it also lowered the ability to have the same sub detected during the day! A sub sitting off from a warship at a very reasonable distance was not detected at all during the day. Actually, like in the stock game, they could be made blind as bats during the day, yet detect you quite well at night. Just the exact opposite of what should occur. Because there seems to be a "default" setting for the night time detection, there was no way to get away from this backward detection. I'm not surprised about this with the game, I've seen many issues that have been revealed to be wrong with the games mechanics.

Another thing is the fact that no two detections are the same. There seems to be a random generated way the sub is visually detected, even though the sub is put in front of the enemy equally. One time the sub is detected within a few seconds of exposure, the next time it may take a couple of minutes. If it's detected at all! This made my testing needing to take an "average" of the subs exposure/length of time calculation. No two are alike in detection time.

So what's it all mean?

Well, it means if you expect to have the game allow you to sneak up onto a target under the cover of darkness, you can forget it. Not without throwing off the daytime detection to the point of absurdity. It also means you need to take several tests of the same ship positions in order to get an average of detection specifics. No two are alike. This also means a players ability to slip by a specific enemy is totally random; trying the same mission another time, will probably give you a different result.

[mobucks]

I find TMO 2.2 to be reasonable in terms of enemy AI detection of my ship. Yesterday I was running at flank speed towards a small TF of 2 small cruisers. They were clearly visible with binoculars. I was running perpendicular to them at full speed undetected, but as soon as I turned and showed them my broadside, they started firing.
Night surface attacks have been made out to 1200m with decks fully awash, the AI merchants never see me on a dark night. I tried a night attack fully surfaced, I think he saw me at 1500-2000yards. I only did this once, so I'm not sure If it was detection or a random zig, I wasnt fired upon because the merchant was unarmed.

[TorpX]

Poking around in the SH III section, I noticed they have the same issues. Sometimes they have situations where their crews can see enemy ships at long distances, eventhough the enemy was blind and could not spot them. Other times the detection ranges varied drastically, due to a absurdly large random influence. They seem to be making some progress toward fixing it though.