submarines, diesel & smoke

Skubber · Joined: 25 Sep 2005 Posts: 106 Location: Rochester, NY, USA

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 · Joined: 14 May 2005 Posts: 234 Location: Berlin

Maybe they made the crew inhale it? :hmm:

Keelbuster · Joined: 17 Oct 2005 Posts: 263 Location: TO, ON

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 · Joined: 07 Jul 2002 Posts: 31

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 · Joined: 10 Jan 2002 Posts: 504

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 · Posted: Sun Apr 30, 2006 3:07 pm Post subject:

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 · Joined: 17 Oct 2005 Posts: 263 Location: TO, ON

Sailor Steve · Posted: Sun Apr 30, 2006 3:36 pm Post subject:

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 · Posted: Sun Apr 30, 2006 4:16 pm Post subject:

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 · Posted: Sun Apr 30, 2006 4:55 pm Post subject:

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 · Joined: 01 Aug 2005 Posts: 179 Location: Sydney, Australia

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

NeonSamurai · Joined: 10 Jan 2002 Posts: 504

Yep low grade fuel can produce smoke.

Oh and your right Sailor Steve my bad Smile

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 · Joined: 19 Feb 2006 Posts: 16 Location: High Peak, UK

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 · Joined: 03 Jan 2006 Posts: 120

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 · Joined: 19 May 2005 Posts: 22

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]