Snorkel in type IXD2 German Uboats

[jorgegonzalito]

Although SH4 is a submarine simulator preferably dedicated to the US Navy, there is a mod that adds a dozen missions and some patrols for the Kriegsmarine Uboats. In almost all of them, the designated submarine is a type "IXD2", some of which had a snorkel, which gave it certain operational advantages, since it could navigate submerged with the diesel engines running. I installed and activated a mod that allows these devices to be added to the aforementioned submarines, and the "Shift + X" key combination makes the snorkel go up and down. But that is where the joy comes, since when the submarine is extended and submerged, it does so with the low speed of the electric motors. In other words, the simulator is not aware that the snorkel is installed and operational. Supposedly the "comma" key is designated for the submarine to dive to snorkeling depth, but in reality its function is associated with the free camera. I don't know if in practice the periscope and snorkel depths are the same, but I suspect they are not. I don't know if this Snorkel is just testimonial, or if there is some way to make it work. Greetings and thanks for your comments!

[Aktungbby]

what speed R U trying to attain on the schnorkel?

[jorgegonzalito]

Originally Posted by Aktungbby

what speed R U trying to attain on the schnorkel?

When submerging the speed is reduced to the same value, as when the uboat navigates powered by batteries.

[Aktungbby]

Originally Posted by jorgegonzalito

it does so with the low speed of the electric motors. In other words, the simulator is not aware that the snorkel is installed and operational.

AS I recollect, 7 knots under water on batteries is top speed attainable. If your on the schnorkel and only at a similar speed that's because 6 knots is the limit! https://en.wikipedia.org/wiki/Submarine_snorkel

Although snorkels allowed submarines to use their diesel engines while submerged, their use had limitations and problems.

U-boats with their snorkels raised were limited to six knots to avoid damaging or breaking the tube. The Gruppenhorchgerät (the boat's hydrophone array) was useless while running diesel engines submerged.

However, the most dramatic effect caused by the use of snorkels was their ability to create partial vacuums within the submarine.rupturing crewmen's eardrums Early snorkels had automatic ballcock valves fitted (to prevent seawater from waves being sucked into the diesel engines) that could slam shut in rough weather, forcing the engines to rapidly draw air from within the boat itself. The sudden reduction in pressure would cause the crew to experience extreme pain in their ears, occasionally causing ruptured eardrums. Atmospheric pressure would then hold the ballcock valve firmly shut, forcing the boat to shut down its diesel engines and surface.[7] The engineering problem still exists in modern submarines; however, the effect is mitigated with the use of high-vacuum cut-off sensors that shut down the submerged boat's engines when any sudden pressure drop is detected. Likewise, modern snorkels have a fail-safe design. An electrical circuit controls a compressed air system that holds a "head valve" open against the pull of a powerful spring. When waves wash over exposed contacts, the control circuit breaks, venting the compressed air, causing the head valve to slam shut. The valve is immediately reopened by compressed air when the contacts are again clear of the water.

As snorkels were designed to draw in and vent gases, a submarine's diesel exhaust could be seen on the surface up to a distance of about 4.5 km (2.8 mi).[8] Also "periscope feather" (the wave created by the snorkel or periscope moving through the water) can be spotted in calm seas. During the early months of the Battle of the Atlantic in World War II, British ships using the radar set Model 271 were able detect the periscope of a submerged submarine at a distance of 800 m (0.50 mi) during tests in 1940.[9]

Bottom line: if SH IV is doing 6 knots that's realistic immersion in the game BBY... Twixt brökken tubes, eardrüms, and telltale 'schnorkel feathers': orders from BdU! Additionally, anything above seven knots would cause a raised periscope vibrate so badly as to be unuseable. As IXD2's were used exclusively in the far Southern Atlantic and Indian ocean, far from home, a cracked periscope tube would spell doom to the long-range mission .

Periscopes suffered from two main problems, the most important was vibration. When fully extended, the long unsupported tube created turbulence on a moving U-boat. At 6 knots, it caused excessive vibration which rendered it almost impossible to use. This was dampened by using an extension bracket to reduce the unsupported length and the pointed end was redesigned to minimize the forward hydrodynamic resistance. Nevertheless, vibrations still occurred, but to a much lesser degree. The other problem was fogging of the lenses. Since the damp atmosphere of the U-boat caused fogging, it was especially important that the tube was not only watertight, but was airtight as well. Any fracture on the airtight casing caused by a depth charge attack would result in fogging of the tubes.

Keep it at 6 and 'mind yer six' when using the schnorkel. https://www.uboat.net/allies/documents/usaaf_asw3.htm

Among the devices that the group helped develop or test were the absolute altimeter, the magnetic anomaly detector (MAD), the radio sonic buoy, improved airborne depth charges, longrange navigation, and airborne microwave radar.

The absolute altimeter used a modified microwave radar to determine an aircraft's exact altitude to within 10 feet (3 m). This altimeter, replacing the less accurate barometric instrument, permitted aircraft to fly safely as low as 50 feet (15 m). The low altitude attack substantially improved the chances of destroying the target. This device was standard equipment on USAAF anti submarine aircraft by 1943.

The magnetic anomaly detector (MAD) operated by sensing a change in the magnetic field of the earth, an anomaly that could be produced by the steel hull of a submarine. Aircraft outfitted with this device would patrol in an area where a submarine had been spotted but had submerged. Combined with the use of a radio sonic buoy to listen for the sounds of a submarine, the MAD permitted an intensive search with a high probability of success. Another important development was the use of LORAN (long range aid to navigation). The aircraft received radio signals from three known points, allowing the navigator to pinpoint his location to within four miles (6.4 km) at a range of 1,200 to 1,500 miles (1,931 to 2,414 km) from transmitters. LORAN permitted efficient control of converging forces. LORAN coverage extended over the Eastern Sea Frontier, Gulf Sea Frontier, and most of the Caribbean Sea and North Atlantic Ocean.

THE FIRST ATTACK ON YOUR BOAT, WITH 'SCOPE AND SCHORKEL RAISED, WILL LIKELY BE UP YOUR '6' BY A LIBERATOR AT 50' OFF THE
SURFACE...'

[jorgegonzalito]

Originally Posted by Aktungbby

AS I recollect, 7 knots under water on batteries is top speed attainable. If your on the schnorkel and only at a similar speed that's because 6 knots is the limit! https://en.wikipedia.org/wiki/Submarine_snorkel Bottom line: if SH IV is doing 6 knots that's realistic immersion in the game BBY... Twixt brökken tubes, eardrüms, and telltale 'schnorkel feathers': orders from BdU! Additionally, anything above seven knots would cause a raised periscope vibrate so badly as to be unuseable. As IXD2's were used exclusively in the far Southern Atlantic and Indian ocean, far from home, a cracked periscope tube would spell doom to the long-range mission .
Keep it at 6 and 'mind yer six' when using the schnorkel. https://www.uboat.net/allies/documents/usaaf_asw3.htm THE FIRST ATTACK ON YOUR BOAT, WITH 'SCOPE AND SCHORKEL RAISED, WILL LIKELY BE UP YOUR '6' BY A LIBERATOR AT 50' OFF THE
SURFACE...'

I was unaware of everything you tell me about the subject. Snorkels were obviously not the panacea that solved the problem, but at least they could perhaps recharge the batteries while diving without attracting too much attention. How to know (in SH4) if at 6 knots the submarine is sailing submerged with diesel or electric engines? I suppose that with the option of limited batteries you could check if they recharge, or on the contrary they discharge. Thank you very much for your detailed answer! It's amazing what I'm learning here every day about submarines!

[Aktungbby]

Originally Posted by jorgegonzalito

Snorkels were obviously not the panacea that solved the problem,

ADM Dönitz having once sent a message to one his U boat aces "Kongrats Kaleun, U haf new baby...mit snorkel!" I can attest in the sense of it...raising the schnorkel is seldom a panacea that solves any problem., especially if it gives away your position to an aircraft with 10 centimeter radar!! My late uncle (passed 2 months ago) age 95; who flew anti-submarine Liberators seldom discussed his wartime experiences, but implied that U-boats didn't have much chance. Essentially WWI technology; upgraded somewhat in WWII, but ultimately no match for Allied technology in the air. Germany didn't just lose the shooting war at sea, it lost the "wizard war" of superior overall technology culminating in the Manhattan Project. Bottom line: as author Blair puts in his Hitler's U-Boat War vol I & II, only sinking 5% of allied shipping overall, from 1939 to 1945, is a poor return for the annihilation of 75% of your entire U-boat force!

[jorgegonzalito]

It's true what you say, they would have needed bigger and more modern submarines since the beginning of the war, like the type XXI. Let's not forget another important ingredient that played against the Germans, which was the cracking of the "Enigma" code by the Allies, which the high command of the Uboats was completely ignorant of. Your comments are very instructive! Gracias amigo!!

[jorgegonzalito]

Sailing at 6 knots submerged the battery remained charged, I lowered the snorkel and then it started to drain the battery. How good!

[Aktungbby]

U R a'learnin' grasshopper! PS: Bresking the enigma code was simply another factor or the "WIZARD WAR".