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.....)

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]

Originally Posted by Rockin Robbins

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]

Originally Posted by Rockin Robbins

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 contains a statement that a flooded down submarine can submerge "in a matter of seconds"
http://en.wikipedia.org/wiki/File:HM...ecks_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!