Congratulations, you have been selected to work in the noisy, fuel-stinking, electrical-sparking pit that is a diesel submarine's engine room! If you haven't climbed into a torpedo tube and launched yourself out of this rust-bucket at the prospect this guide may help you and your crewmates survive your upcoming missions.

This guide is compiled for Iron Wolf 1.13.1.0 (Early Access).
Stuff may change. I'll try to update it as I remember.

The engineer's station is equal parts boredom and chaos - it can be a pretty fun position for the right crew member though. As the boat's engineer you have a lot of responsibilities:

• You are the one who actually sets the boat's speed.
  The captain may think they're in charge, but if you don't tell the engines to turn the boat don't go.
  
  
• You are responsible for maintaining a charge in the boat's batteries.
  Whether it's firing a torpedo, steering the boat, or just keeping the lights on you need power to do it.
  
  
• You are responsible for maintaining air in the ship's tanks.
  Making the boat go down is easy. Bringing it back up again takes air though, and you're the one who runs the compressor that fills the air tank.
  
  
• You are responsible for managing power to the boat's systems.
  Look there's only so much power and everyone wants some, and you decide who gets it.

In addition to these tasks you may be called on to run around the ship fixing leaks or helping to pump out flooded compartments.

It sounds like a lot, and it is: The engine room can get very busy in combat.
If you approach it right it's actually an easy station to operate.

Do you hear those bells ringing like an angry alarm clock?
I think the captain is trying to get your attention!

Being a fine piece of vintage 1940s technology the captain does not have direct control of the engines from the conn. Instead they operate a telegraph lever which repeats their orders to the engine compartment. You look at what the telegraph says and set the electric motor speed accordingly.

To do that you use the starboard-aft control station:

1. Engine Order Telegraph
   This is what keeps making those stupid bell noises. It's sole purpose is to annoy you when you have more important problems to deal with... er, I mean to tell you what the captain wants the boat's engines to do.
   
   
2. Electric Motor Direction
   So funny thing about a diesel submarine, it's really an electric boat with diesel generators, and this handle determines which direction the electric motors turn.
   Handle go up, boat go forward. Handle go down, boat go backward. Simple!
   
   
3. Electric Motor Power
   This handle determines how fast the electric motors turn, and it's almost as simple as the direction handle: If the handle is all the way down the electric motors are off. If the handle is up the electric motors turn at full speed (limited by the amount of power you've diverted to them).
   
   
4. Battery Gauge
   When the Electric Motor Power handle goes up the battery gauge goes down.
   When the Electric Motor Power handle goes down the battery gauge... goes down slower.
   When the battery gauge gets to zero the electric motors stop. Also the lights, and well pretty much every other thing on the boat except the captain. The captain gets very loud.
   Do not let the battery gauge get to zero.
   
   
5. The Motors
   This little red wheel at the back of the engine compartment is one of the sub's two motors. There's another just like it on the other side. When you push the Electric Motor Power handle up this wheel spins. As best I can tell it's just decorative, but it's there and I guess you should know about it.

The Starship Enterprise was designed by the best minds in the federation's engineering corps.

This rusty monstrosity on the other hand was designed by Hans & Franz. We found them in a bar, they may not even BE submarine designers, and I'm pretty sure they were on a wicked schnapps bender when they built this one.

Nonetheless the captain expects you to make it all work so let's talk about power distribution - the port side bulkhead of the engineering compartment is devoted almost entirely to a fuse panel, and you're going to be getting very familiar with it. Let's take a look:

1. The Main Breaker
   A big ol' red switch. Pull it to off and the entire boat shuts down.
   You really never want this to be off. It makes the captain yell, and yelling is not good for a schnapps hangover.
   
   
2. Power System Gauges
   There are three power system gauges above the fuse panel. They are:
   
   • Charge & Draw Rate
     This shows the amount of power generated by the diesel engines (the thin black line, currently at zero all the way to the left) and the amount of power being drawn by the boat's systems (the thin red line, about 1/3 of the way to the right on the gauge).
     If the black line is to the left of the red line the batteries will drain. If the black line is to the right of the red line the batteries will charge. The rate of drain or charge is proportional to the distance between the two lines.
     
     
   • Load Warning
     Hans & Franz built this boat on a budget, and one of the places they cheaped out was in the power distribution system: Hans wanted to put in heavier gauge wire and more efficient equipment, but Franz spent the electrical budget on a bottle of Blackhaus so all they could afford was this ammeter. They painted the end red. Stay out of the red part or Bad Things Happen.
     (We'll talk about Bad Things Happening a little later).
     
     
   • Battery Capacity Meter
     Jeez, another one? Well just like the round gauge on the starboard bulkhead behind you this gauge shows the current charge in the batteries. If it gets to zero the lights go out and the captain starts yelling and blah-blah-blah. Don't let this gauge get to zero.
   
   
3. The Fuse Panel
   You know what a fuse panel is. If a piece of equipment draws too much current its fuse will blow.
   This fuse panel also has a switch above each socket that lets you control whether or not that circuit has power going to it, We'll talk about what each system does in another section.
   
   
4. Spare Fuses
   Along the bottom of the fuse panel is a row of spare fuses. They come in 10 amp (red) and 30 amp (yellow) ratings. You'll need to use these fuses if Bad Things Happen.
   
   
5. Pressurized Air Gauge
   I know what you're thinking: "That's not electrical!" and you're right, the pressurized air gauge is the only thing on this panel that's not related to electricity. Pressurized air is used to blow the boat's ballast tanks and drain the torpedo tubes.
   Why is it on this panel? The answer is right to the left of the gauge: The switch to control the air compressor is right here. You can only run the compressor when the ship is on the surface (or at periscope depth with the snorkel extended), and it's your job as the boat's engineer to do so and make sure there's air in the tank so that when the captain makes the boat go down you'll be able to go back up again.

As the boat's engineer you're responsible for deciding what systems get power (and how much power they get). You will use the power switches on the fuse panel to balance supply and demand while keeping your total load out of the red zone on the load meter to avoid Bad Things happening.

Let's look at the various systems and how they use power:

• Lights
  There's a whole column of fuses just devoted to the lights inside the boat, and these are self explanatory: When the switch is on that compartment has light. When the switch is off that compartment has no light (and any crew members in it will need to use their flashlights to see).
  
  
• Electric Motor
  These are pretty self-explanatory too: Remember in the Engine Controls section where I said the maximum engine RPM is limited by the power you give them? This is where you give them power. Each circuit corresponds to about 1/3 of the electric motor speed range, and with all three circuits on the motors will make full speed when you put the speed handle to its maximum limit.
  Turn off all three circuits and the motors won't work at all.
  
  
• Torpedo Computer
  This is what your crew uses to calculate firing solutions when they lock a target from the periscope.
  If it's turned off then you can only fire torpedos from the torpedo room, and they'll just go straight ahead until they hit something or run out of fuel.
  

  I'm not sure what effect turning on more torpedo computer circuits has. I believe it makes calculating the firing solution faster, but I haven't timed it.

  
  
• Rudder and Planes
  This controls power to the circuits that move the ship's rudder and dive planes.
  
  • If both circuits are powered you can use the "Set Heading" switch in the conn to program a heading and the boat will turn to hold that course. You can also move the rudder or dive planes to the full limits of their travel.
    
  • If only one circuit is powered you cannot use the "Set Heading" switch - the tiller wheel functions as a rudder control only. In addition the travel of the rudder and dive planes is limited.
    
  • If you turn off both circuits the rudder and dive planes cannot be moved, which means the boat cannot be steered. Turning off both circuits usually makes the captain yell.
  
  
• Torpedo Racks
  These circuits power the torpedo racks. The rack motors help your torpedo crew load fish into the tubes, and turning more circuits on makes reloading faster.
  
  
• Air Compressor
  We pretty much covered this one earlier: Turn this switch on and the air compressor runs, pumping more air into the pressurized air tank.
  The compressor uses a lot of power so when the pressurized air tank is full you should turn it compressor off. (Most boats have an automatic switch for this, but Hans spend the money for that component on a bottle of Kirschwasser so you have to do it manually.)
  
  
• Hydrophone
  The hydrophone is a big underwater microphone with a wheel to aim it and a speaker to listen to it, located in the sensor compartment. This circuit powers the hydrophone motor and amplifier.
  If you're already engaged with the enemy then you can turn off the hydrophone if you want, but if your crew needs to find enemy vessels at a distance the hydrophone is how you do it and you'll need to turn it on.
  
  
• Map Display
  This controls power to the big map in the control room.
  If you turn it off nothing appears on the map.
  

  I haven't experimented to see what you lose with only one circuit powered.

  
  
• Terrain Display
  This controls power to the pull-down seafloor display in the control room.
  You can almost certainly turn this off. I don't know how a vintage 1940s submarine got this kind of technology, and if your captain is any good they can use the two depth gauges (depth and depth under keel) to form a mental picture of what this display would tell them.

So far we've talked a lot about things that use power, and I've told you that you can't let the battery level get down to zero or the lights go out and the captain yells, but the battery is draining fast.
How do we keep the battery from getting to zero? Easy: With the diesel generators.

The diesel generator controls are in two places.
Let's start with the starboard bulkhead, which has the Snorkel and Starter controls:

1. Depth Meter
   As the boat's engineer you get your very own depth meter. To run the diesel generator the boat must be on the surface or at snorkel depth (within the blue arc).
   
   
2. The Snorkel Wheel
   When the boat is not on the surface you need to extend the snorkel to get air to run the engines or feed the compressor. Turn this wheel to move the snorkel between its stowed and upright position.
   
   
3. The Snorkel Status Lights
   These are pretty simple: They tell you if the snorkel is upright, stowed, or in an intermediate position.
   
   
4. Snorkel Overflow
   This is literally a drain hole connected to the bottom of the snorkel pipe. If the snorkel is underwater (either because the boat is below snorkel depth or because you're cranking it up or down) water will pour out of this hole. (The boat design called for an anti-return valve here but the shipyard spent the money for that on a cask of Cannabia.)
   
   
5. Battery Gauge
   It's like you can't turn around without seeing one of these huh?
   Shows the charge in the battery. If it gets to zero your crewmates may commit a different kind of battery upon your person.
   
   
6. Diesel Starter Switch
   Pull this switch down to run the diesel engines. Push it up to stop them.
   I presume the switch is backwards because it was installed after the cask of Cannabia was consumed.
   
   
7. Diesel Fuel Gauge
   Operating the generator trades relatively small amounts of diesel fuel for relatively large amounts of electricity. If you let the diesel gauge get to zero the battery gage will soon follow. The last engineer who let both gauges get to zero was launched from a torpedo tube. (Those are pneumatic for a reason.)

There's really not much to do on the starboard bulkhead: Extend the snorkel if you're submerged, then flip the starter switch and move to the port-aft station and the generator controls:

1. Fuel Pump
   The diesel generator's throttle. Push it up, the generator gets more fuel, it runs faster, and it generates more power. It also generates more heat.
   
   
2. Generator RPM
   How fast the generator is turning. Controlled by the fuel pump, and affected by temperature.
   
   
3. Charge Output
   How much power the generator is producing - pretty much directly proportional to RPM.
   The value on this gauge matters less than the Charge & Draw Rate gauge to your right - keep the black Charge needle equal to or greater than the red draw needle over there and the batteries take care of themselves.
   
   
4. Cooling Pump
   Controls how much cooling water circulates around the diesel engines. Use this in conjunction with the fuel pump to keep temperatures in the optimal range.
   
   
5. Cooling Flow
   Shows how much cooling water is circulating around the diesel engines - it's more precise than eyeballing the cooling pump lever.
   
   
6. Diesel Engine Temperature
   Diesel engines are pretty reliable, but they don't like to run when they're too hot or too cold.
   Use the fuel pump (throttle) and cooling pump to keep engine temperatures in the green arc for best power generation.

At the extreme ends of the temperature gauge the engine will barely run, and it will be unable to generate enough power to even run the boat's lights effectively. On the other hand if you keep the temperature in the green arc you can easily generate more power than the boat can use (allowing you to charge the battery while doing all your other normal tasks).

If your engine is cold you can leave the cooling pump shut off and tun the fuel pump at whatever setting produces maximum RPM until the engine warms up. Once it does balance the engine by adjusting fuel and coolant flow until the temperature is stable.

If your engine overheats significantly it will begin to lose speed (the RPM gauge and charge output will start to fall. If this happens you should immediately run the cooling pump up to maximum and cut the fuel pump to 50% or less until the temperature is back in the green arc.
It does not appear to be possible to damage the engine by overheating it, but it will take time for the engine to cool and generate power again which may be the difference between surviving an engagement or being sunk.

It's probably possible to balance the fuel and coolant flows perfectly so the temperature doesn't move, but that is not a skill I have mastered. If you're running the diesel generator check the gauges frequently to ensure it's running the way you want it to.

If you stay near the center of the green band and have the controls reasonably balanced you can move to other compartments to assist with damage control or other tasks, but remember that the engine room is your primary responsibility. You do not want to let the battery run down to zero because the diesel engine stalled, and you definitely don't want to flood the whole boat in a crash dive because you forgot the snorkel was still extended.

If you overload the power panel by going into the red zone on the ammeter Bad Things start to happen, and you will only have a few seconds to act to prevent disaster.
You will hear an electrical buzzing / sizzling sound from the fuse panel and the submarine's lights will pulsate, getting brighter and dimmer. If you act quickly to reduce the load that's all that will happen, but if you fail to stop the overload fuses will blow and the main breaker will trip.

Fuses may also blow and trip the main breaker due to battle damage.

When this happens you will have to work quickly (in the dark) to restore power to your boat.
Grab your flashlight and pull all the blown fuses out of the panel, then reset the main breaker. Tou can identify the blown fuses easily: They will be black.

Note that the main breaker cannot be reset if there are blown fuses.

Once you have power back on grab fuses from the spares at the bottom of the panel to replace the ones you pulled, but take care not to overload the panel again if that's what caused the fuses to blow.

You CANNOT substitute a 10-amp fuse for a 30-amp fuse - it will blow instantly and trip the main breaker. (I am of the opinion that you should be able to substitute 10-amp fuses into the electric motor circuit and they should only blow if you demand more RPMs than can be supplied with the fuses installed, but right now ANY 10-amp fuse in a slot that started out as a 30-amp fuse blows instantly.)

You can substitute a 30-amp fuse for a 10-amp fuse, but this is dangerous: The equipment can now draw 3 times the power it was designed for through that socket, and it <i>will</i>.You can easily overload the panel if you aren't careful. and the developers may see fit to punish us for overloading circuits in other ways one day.

Note that the system power draw seems to equal the sum of enabled fuses.
This means if you put a 30-amp fuse in a 10-amp socket you can fully power most of the 10-amp systems that use 10-amp circuits.
For example if you put a 30-amp fuse into the Rudder & Planes bus then you do not need to turn on both circuits to use Set Heading mode or move the rudder/planes to their maximum limits: Just enable the circuit for the 30-amp fuse and the system is fully powered.

If you overload the power panel it sets off a cascade failure: LOTS of fuses are going to blow even after the main breaker trips. I consider this a bug, so I'm going to share a way to work around it: Fuses have to be in active holders in order to blow, so if you pull the fuses from the panel and stick them in the spares bar at the bottom they won't be damaged by the cascade after the panel overloads. Save as many as you can, but especially save some of the precious 30-amp fuses!

As of 1.13.1.0 you can go through the little gate in the engine room, but there doesn't appear to be anything to do back there: I've never seen any of these pipes spring a leak and you don't seem to be able to adjust anything on the diesel engines or electric motors.

It's nice to look at though, and maybe more stuff will be added here in future updates.