Although I fully realise that posing real life question in the context of WH40k is always frought with danger, I am nevertheless again seeking the font of knowledge of the forums. My Navigator has recently aquired the 'Void Watcher' power and this has again driven my mind to the question of Emission Control in Warhammer.

Let me first illustrate its importance in real life. EMCON is one of the vital questions any force commander has to ask itself, and can be simplified (ignoring communications, which is a chapter on its own) into: Will I go active or not. The problem faced here is that if you use an active emitter (sonar, radar, ladar, etc.) to gather information you give away that you are there and even make that presence known at ranges far beyond your ability to register return signals. Submarine warfare offers the best example of this dilemma. The enormous active sonars can instantly give a good idea of everything in the neighbourhood of a boat, but the emissions of this sonar can even be picked up on the other side of the ocean and instantly give away a large part of the main strength of any submarine, i.e. stealth. The result is that submarine almost always limit themselves to the use of their passive sonar and only go active in dire circumstances.

Now, back to Warhammer. The main problem is that we have to pose the question how the Augur Arrays on a ship work. To me, it seems that they will contain a mix of active and passive sensors, some of them working on visual wavelengths and others using a whole array of things only Omnissiah understands. One of the reasons (except logic) for this assumption is the ability of a ship to use the 'active augury' and 'focused augury' actions during ship combat. The first being a sweep of the entire environment giving (when succesful) a clear idea of everything in the void around the ship, the second giving detailed information of another ship (or rock, or rock sprouting a load of guns). Active Augury as such seems to be a clear example of activating the 'radar' to make a clear sweep of the environment, with the name being a bit of a give away. Focused Augury is less clear, and could be a mix of active (synthetic radar images) and passive (electro-optical, infra red and analysis of their emmissions) techniques.

Now, if these assumptions are correct, what would be the results:

- If a ship uses Active Augury, they give away their presence and a foe can detect this presence, even from beyond the detection range of the ship itself (although this will only give bearing information and data on the augur arrays used).

- If focused Augury uses active sensors, the ship subject to this Augury will detect this.

Translating this into rules, a first attempt would be:

- Using Active and Focused Augury breaks silent running.

- Using Active Augury allows any ships within 50 VU an automatic scrutiny+detection test to detect the presence of a ship, with information of its bearing and limited information (such as Imperial or Ork) on the nature of the ship. Mind you that two or more ships with a bearing can use triangulation to get a more specific location. Alternatively, you might wish to use modifiers, such as within 10 VU +30, 20 VU +20, 30 VU +10, 40 VU normal and 50 VU -10, but that seems a needless complication and can always be adjudicated on the spot by the GM.

- Using Focused Augury allows the target an automatic scrutiny+detection test to gain the same information as above.

The result of implementing these rules would be that automatically using active augury all the time would put you in the same position as someone using a lantern in a moon lit night. You see far better what is just around you, but everyone will see your lamp moving (darn, I should have thought of this comparison a bit earlier in my text). This would make EMCON a part of the captain's dilemma and complicate matters, but seems to me interesting enough to incorporate in the game.

Friedrich van Riebeeck, Navigator Primus, Heart of the Void

van Riebeeck said:

I can see the train of thought here, but I imagine that while it is an issue, it's not as great an issue as it would be in submarine warfare - afterall, the biggest clue to a starship's presence in space is its heat signature, which is necessarily colossal, especially given how cold the surrounding void is (a vessel driven by a massive plasma reactor as both power supply and propulsion, surrounded by a near-infinite expanse of vacuum at almost absolute zero... just sitting there is like being a lantern lit in total darkness).

As a result, I see emission control as being more significant before and after battle (particularly when you've left combat by Silent Running, as that is very clearly noted as being a matter of emission control) than during it, simply because once you're in battle your vessel is emitting so much heat and radiation that it's difficult not to notice you.

I like the idea, but to be honest: we need to know what kind of techniques the augurs use. They could just be activating a whole range of devices that measure a lot of different variables on the hull. For example: they could be measuring heat, radiation, light, warp energy readings, things we can't think of but the omnissiah in his wisdom did, ... .

Active augury in such a context would be not so much akin to a sonar (sonar wouldn't work in space as the sound has no medium to go through), but more akin to using a query on a gigantic database of evershifting data. Compare the readings we have with the following parameters and give me back what's there.

Focused augury would then be actually emitting something that'll generate feedback allowing you to make better judgements on exactly what kind of equipment a ship is using. However, i don't see how this would then in turn give away anything to said enemy ships unless it's what kind of augurs you use. Giving them the option of in return seeing all your ship components seems to be serious overkill.

Apart from emulating reality, another reason for these questions is more a matter of game balance. If Active Augury has no disadvantages, there is no reason whatsoever for ships not to use it continually. Both PC ships and NPC ships would in that case use this ability all the time and as a result make Silent Running a thing of the past. If on the other hand, there is a penalty to Active Augury the advantages of comprehensive area awareness would be balanced by the disadvantages of detectability. This balancing of advantages with disadvantages is in my opinion always a good thing in a game and would make Silent Running a real option.

Obviously, these rules would impact ships actions before battle far more then ship actions during battle, as has allready been noted. Once the macrobatteries and lances start to speak, EMCON becomes a bit of a moot point. But when your ship is sneaking about around 'Undred 'Undred Teef, it is vital. Will we go active and try to detect Ork ship before they can ambush us? But if we do, they will quite likely know we are here and come looking for us? Can we avoid the Ork ship whose emissions we detected? Etc., etc.

FvR

wel, normally the extended actions (such as active augury) are only available during combat. However, because saying that to a player would be the epitome of lame, personally i rule active augury to be an opposed test pitting scrutiny + detection vs pilot (+10) + manoeuvrability.

I also rule the following:

raiders get a +20 to go on silent running

transports get a +10

Frigates get a +0

Light Cruisers get a -10

Cruisers get a -20 and so on for every size increase

Sure it makes raiders good at sneaking up, but it's more or less part of their concept: surprise the enemy and get a good shot in before he can react. Because if he gets time to shoot once at you, you'll be venting air soon.

I do like the idea of opposed tests. I would only change the ship classes to Megatonnage, as it is hard to see a Mass Conveyor sneaking up on anybody. But then, it is hard to see it swinging its huge bulk in tight 45 degree turns as well.

FvR