Iron Coffins mod changes and improves the underwater damage control and survival mechanics. Changing the internal pressure handling, air and water flow between the compartments, interactions with the hatches and ballast, blocking of leaks, realistic air usage by devices and much more!


► Tested on game version b131.
► All features of the mod are working without the need to start a new career.
► Mod uses custom actions for leak blocking, repair and others, which are saved to the savegame when they are in use. If you want to disable the mod, the safest way is to dock, have all damage and leaks fixed, save and disable the mod on next game start. I have found few cases, where unsubscribing from the mod prevented the save where it was used from loading, even after doing this procedure however. Please let me know in case of any issues.
► This mod requires the Custom Actions mod to work properly, please make sure you are subscribed to it and it is enabled in the launcher.
► No compatibility problems with other mods are known at this moment, except the incompatibility with IBC mod.

► As in its predecessor, the Improved Ballast Control mod, all of the ballast controls are unlocked in most of the conditions unless damaged or the Uboat is docked.
► Most importantly, the ballast adjustment is possible to be done repeatedly to compensate for water pumped out, flooded in, or change in depth.
► There is no flooding / negative buoyancy requirement for the adjust ballast action, it can be done at any time.
► Performance of the adjust ballast action was improved for situations where you have to compensate for excess of positive buoyancy. Tanks are now flooded faster.
► Adjust ballast for deck awash action, which sets the ballast to 40% was added. Activate this either from the valves or using the button next to the depth control to go deck awash.
► Blow ballast by diesel action is added. It can be started from the valves, or to automate the process, you can set the depth manually to 1m (dedicated depth control button will be added later). Obviously the diesels must be functional and running. Blowing by diesel exhaust is slower, but saves the precious compressed air.
► If there is ongoing action at the valves, like blowing the ballast and you order for example crash dive, the ongoing action is cancelled immediately and the new action is started. This improves the emergency reactions.

► Dive planes are moving according to internal steering angle. Angles are limited to real steering angles and also the front steers are not used at speeds greater than 9-10kn.
► Depth steering control at low depths was reworked, it is now possible to surface the boat dynamically just using the dive planes to have the opportunity to turn on the diesels. Having officer at depth steers greatly improves the performance and surfacing dynamic. The depth steering control is still vanilla code, I for now just worked around it to implement this and this might be changed in the future as I do not completely like everything, for example having the officer present immediately boosts the force the depth steers are pushing the boat by 2x.
► Sailors are staying at the dive plane controls during deck awash, this greatly improves the diving response.

► Vanilla compartment pressure handling was overhauled and the internal pressure is now correctly calculated based on the amount of water and air in the compartment.
► Additional to vanilla water flow mechanic, air flow is also modeled between all compartments.
► Air will transfer between compartments only when the water level is below the upper edge of the hatches and also the conning tower hatch skirt. Air pockets are therefore correctly formed.
► Air is now consumed by various devices and the pressure has to be closely watched.
► Air can escape from leaking compartment depending on the hole location (this is existing vanilla mechanic).
► Air is exchanged with outside (pressure equalized) through conning tower hatch and vents to the control room and through diesel intake and snorkel into the diesel engine room.
► Light bulbs gets destroyed in flooded compartments if the pressure is high enough.
► There is at this moment no link between the compartment pressure and the "oxygen" resource.

► Dedicated "Block leak by regular sailor" action has been added to make sure the sailor and not an officer is sent to block the leak. You can assign sailor to block leak from first person as well. If the action is "greyed out" in the section view, make sure you have no officer selected.
► Vanilla block leak action has been reworked and now allows to send other officers than the one you are playing from the FPP to block the leak, similar as the repair action. Since the the slots in the interaction wheel are limited, the officers are displayed there in same order as they appear on the bottom of your screen in section view.
► Vanilla automatic blocking by sailors is enabled at this moment, but will be configurable in the future.
► After the changes in b129, it was not possible to send two characters to some of the holes, for example have two of them blocking or one blocking and one repairing, this is now fixed and all leaks should accept two characters.
►When the leak is being repaired, the flow progressively decreases as the repair progresses, for example 50% reduction when repair is at 50%. This of course stacks with the effect of additional character blocking the leak.

► All hatches now display pressure on their opening and closing sides.
► When pressure difference from the hatch opening side is higher than 1 atm, or there is significant water level difference, the hatch is now blocked ans cannot be opened (will be configurable).
► Blocked hatch should completely prevent entering of the compartment (if not please report as bug).
► New action allows to open valve between compartments to slowly equalize the pressure. Water and air will pour from the compartment with higher pressure into the compartment with lower pressure, and hatch will be opened when the pressure difference drops low enough.
► Hatches will only get damaged when pressure difference across them is over their rated pressure. Open hatches are not damaged from the pressure anymore.
► Damaged hatch will either start leaking or blows open, depending on if the higher pressure was applied from the opening or the closing side respectively.
► When hatch starts leaking, it is possible to block the leak. There is only one slot available for this action, but one sailor will still block the leak efficiently.
► Damaged hatch can be still closed, but will open again at fraction of its undamaged rated pressure, when higher pressure is applied from the closing side. Repairing the hatch during this condition will prevent it from opening.
► Hatch is held closed during repairs and sailors cannot cross it.
► TBD Action to lock the hatch in open or closed state by officer.

► Diesel engine and compressors actually consume air, but the amount is scaled down for now and will be tweakable. (the values are far from realistic, especially for the compressors). You needed about 4000m3 of air at 1atm to completely fill the compressed air flasks and VIIC internal volume is about 400m3. You could not run the compressor underwater in reality, the crew would be killed before you pump any significant amount into the flasks.
► When running with snorkel and the snorkel head undercuts the water surface, there is temporary underpressure created.

► New action which can be used in emergency to dismantle non essential equipment to allow critical repairs has been added. Dismantling yields one part of scrap by default and two parts with Thrifty skill. You can repeatedly dismantle and repair some device to train you engineers at the cost of the spare parts as there is some loss involved as described below.
► Salvage scrap now requires 4 pieces of scrap (instead vanilla 2) to compensate for dismantle action, so fully skilled mechanic can dismantle some device to obtain two pieces of scrap, make spare part and after successful repair will get one more part of scrap back. Therefore repeated dismantling and repair will be always lossy process.
Having the Thrifty ans Salvage skills is very important, but you can obtain them by training your mechanics using the new action. (I will make the Scrap to Spare part ration configurable in the future).

► New toggle actions have been added to the new "Toolbox" device in the stern torpedo room. You can customize various mod settings there.
► Settings are preserved in the savegame.

► Durability of rebreathers is increased by approx 2.5-3 times (there is small random factor added). This is not modified through datasheets and is effective immediately. If you additionally use other rebreather mod, this effect will stack.
► Drowning mechanic is reworked a bit (still not final) resulting in longer (average) time till the sailors drop from drowning.
► Mod disables the automatic hauling of fallen (injured/drowned) crew members to safety by other crew. This is extremely annoying when most of the officers attend to carry sailors while the boat is in grave danger and this action was not possible to be interrupted in vanilla.
► You can manually assign the fallen crew members to be carried to safety if you consider it practical in the situation, but sometime sacrifices has to be made for the survival of the whole boat.
► Drawing order of tooltips for the wheel menu has been brought in front of other UI elements to improve readability.
► When officer is ordered to go into already evacuated compartment, he will stay there, instead of running away after he finishes the current task.
► Evacuation action can be now cancelled by right-clicking on the action in the action queue or in the officer's action queue. This will only permanently cancel it for the officers. Evacuation for sailors will be triggered again, while they are still in the compartment that has to be evacuated.