submarines, diesel & smoke

[Skubber]

A general sub knowledge question:

How did the uboats (or any WWII subs for that matter) manage to burn diesel and not produce smoke like other ships do?

I had heard that early in the war, there were some problems with German subs producing white smoke, but these were resolved.

How was it resolved? Where did the smoke go?

[GlobalExplorer]

Maybe they made the crew inhale it? :hmm:

[Keelbuster]

I assumed/heardsomewhere that they emit the exhaust through the props somehow so it gets dissolved in the water and doesn't surface and go gaseous.

Good Q.

Kb

[Manock]

Really! Far Out. A clever solution. Maybe its just imagination, but I have wondered why there were so much cavitation bubbles even at low speeds while surfaced.

[NeonSamurai]

Umm properly maintained and tuned diesel engines dont produce visble smoke, just look at any diesel city bus (assuming they are properly maintaining it). Diesel engine exaust is only black when the engine isnt turned and burning all the diesel fuel, instead its only partialy burning it and creating soot, this also wastes a fair amount of fuel (as its not being converted to energy)

I belive the exaust gets vented along the back side of the coning tower, they definatly dont vent it underwater in the maner described. As for the cavitation, thats typical of props of that period (plus they didnt realy model it in game, you look to be cavitating any time the props turn even doing 1 knot)

None of the surface ships use diesel, they are all steam driven with coal fires (think steam locomotive on a much larger scale). The reason why sub's dont is because could you imagine working a steam boiler in one of those cans? Coal produces alot of heavy thick smoke.

[Sailor Steve]

Agree with Neon Samurai except for the coal part. Coal fired ships were a rarity by WWII, at least the warships, which all burned fuel oil. Produces a lot less smoke than coal, which in WWI was so bad that ships couldn't go to full speed while firing, or the smoke would obscure the rangefinders.

[Keelbuster]

e exaust gets vented along the back side of the coning tower, they definatly dont vent it underwater in the maner described.

Hmm - har. Why didn't they vent it into the props and dissolve it?

[Sailor Steve]

I read a story once that a u-boat was attacked by a destroyer that saw smoke coming from the water-turned out it was coming from the snorkel.

[SubSerpent]

I wish the smoke trails that followed the ships would be as long as they actually were in real life. Would be cool to see smoke stretched out across a light blue sky for miles!

[Sailor Steve]

I feel the same way about wakes. After the foam dies, the water is still discolored for miles. That's how airplanes found subs and convoys before radar.

Depending on the ship type and engine states, a lot of them didn't produce much smoke.

[bookworm_020]

A high sulfur content in diesel also produces the black smoke that you see.

[NeonSamurai]

Yep low grade fuel can produce smoke.

Oh and your right Sailor Steve my bad :) but im pretty sure alot of the non warships still used coal though. Oil burning ships should have a fair amount less smoke then a coal burner, and diesel providing the engine is turned and not damaged (or using poorly refined fuel) should produce none at all (other then some white smoke in cold weather)

As for venting underwater, well the biggest issue is water pressure vs exaust pressure, plus the risk of the water backing up. Its also easier to do it verticaly and install safeguards that will stop water backflow, rather then horizontaly. Another thing they would do when surfacing and first firing up the engines im told is vent the exaust into the the ballast tanks which not only helped empty them, but also helped protect them from rusting due to the oil in the smoke when the engines are first started.

[U2222]

There were still a high portion of coal burning merchants through WW2.
Even oil burning steam ships will produce smoke dependant on the air/fuel mix, burner flash up, fuel temp etc.
Diesel submarine engineers were very keen to keep the diesel injectors well maintained. Poor / faulty injectors is the No 1 fault leading to exhaust smoke and easy identification by the enimy.

[BigBadVuk]

Well...there is a few mods wich affect wakes and smoke..Is there any way to reconfigure them and make smoke visible for much longer time(maybe this is the problem becose for the game the smoke from burning ships is the same as smoke from the funnels..),But for the wakes...im shure that something can be done..it will be so cool to see wake on surface,then following it after few miles u stumble upon lonley ship or convoy or even DD...he he he..that would be cool

[SciFi25]

In 1940 the british government ordered 60 ships to be built by American shipyards all with coal fired boilers. http://en.wikipedia.org/wiki/Liberty_ships This was because at the time Britain had no native oil fields but had abundant coal resources.

I don't think military ships used coal fired boilers, HMS Hood, HMS Nelson and HMS Ark Royal certainly didn't.[/url]

[rogerbo]

i only know that the Germans did build their BBs and Cruisers with Diesel Engines which gave them a much biger range and also a biger speed. The Spee had a range of about 20'000 sm, and the Sharnhorst a speed of about 32 kts. I dont know exactly how many British ships did run on Diesel but i would expect that after the WW I experiense they would have converted them to Disel as well.

Yes a well maintainde Diselengine won't produce smoke when running. It can happen when starting or Accelerating the Engine that it will produce Blacksmoke doe to the higher Oil burning.

[joea]

i only know that the Germans did build their BBs and Cruisers with Diesel Engines which gave them a much biger range and also a biger speed. The Spee had a range of about 20'000 sm, and the Sharnhorst a speed of about 32 kts. I dont know exactly how many British ships did run on Diesel but i would expect that after the WW I experiense they would have converted them to Disel as well.

Yes a well maintainde Diselengine won't produce smoke when running. It can happen when starting or Accelerating the Engine that it will produce Blacksmoke doe to the higher Oil burning.

Wrong!!!! Only the panzerschiffe "pocket battleships" (Graf Spee, Scheer, and Deutschland/Lutzow) used diesels and had a very long range. Not sure about the light cruisers, but the Hipper class cruisers, Scharnhorst class and Bismarck class BBs all used oil fired turbines. Furthermore the Hipper class had machinery problems and never were well suited for commerce raiding.

As far as DDs and the Torpedoboots (like small DDs) they also used oil fired steam turbines, the schnellboots used diesels though and were fine vessels. :know:

[tycho102]

Diesel engine exaust is only black when the engine isnt turned and burning all the diesel fuel

Exactly. Subs usually accelerate and hold a constant RPM. But to add to the explanation:

Fuel-oil isn't diesel. Diesel isn't fuel-oil.

Surface ships tend to burn fuel-oil, even in this day and age. Diesel actually takes quite a bit of refining in comparison to fuel-oil (which is basicically 50% diesel, and 50% sweet-light crude). Subs burned diesel because it has greater energy density and space on a sub is very premium.

[Coort]

In 1940 the british government ordered 60 ships to be built by American shipyards all with coal fired boilers. http://en.wikipedia.org/wiki/Liberty_ships This was because at the time Britain had no native oil fields but had abundant coal resources.

I don't think military ships used coal fired boilers, HMS Hood, HMS Nelson and HMS Ark Royal certainly didn't.[/url]

To add some interesting information about coal ships:
between 1939 and 1945 many of merchants and passenger liner used coal fired boilers, and some of these ship literally blowed up when hit by torpedo, a good hit in the coal stock compartment easily ignite greater explosion because of coal dust filled the air acting as gas.