Schnorkel usage - Pros and Cons

[panthercules]

I finally had one of my Kaleuns make it far enough along in the war to get a schnorkel for my new Type VIIC that I got upon my return to active duty in mid-1943 after a 6-month tour as an instructor at the U-boat school.

However, the more I've thought about it the less inclined I am to actually use the thing. As it has turned out, I've only used it once, when I was barely able to sneak away from some persistent escorts and was running out of air and batteries but was still too close to the escorts to risk surfacing since they would most likely spot my surfaced boat on radar. I figured then that if they did spot my schnorkel I would be able to tell via the hydrophones that they were approaching so the reward (continued life) was worth the risk.

However, I can't bring myself to use the schnorkel for routine operations. The way I see it, if I'm surfaced and there are aircraft or ships that wander by, I've got a pretty decent chance (at least during decent weather) of spotting them in time to take evasive action and/or dive to safety. However, if I'm cruising along on the schnorkel, with no reasonable aircraft detection capability myself, the first way I'm going to know I've been spotted by aircraft is when the bombs/DCs explode, and it'll probably be too late to do anything at that point.

If the weather is bad enough to mask the schnorkel (and its associated wake) from visible detection by aircraft (and I'm not even talking radar detection yet - I'm assuming that we Kaleuns would not consider it likely that the Allies' radar could detect something as small as a schnorkel at this point in the war anyway), I suspect it would be bad enough to make operation using the schnorkel impractical, so I'm having trouble thinking of a situation when I'd actually use this thing (other than the emergency one I already encountered as noted above).

If you cruise with both the schnorkel and the obs scope raised, would doing so give you a reasonable chance to detect enemy aircraft before they reach you and drop their bombs (would you get any "aircraft sighted" type report from your crew this way)? Do you just use the schnorkel instead of surfacing at night, when the aircraft would be less likely to spot the schnorkel/wake (and your lookouts would be less likely to spot any approaching aircraft anyway), and basically stay submerged the whole time at this point in the war?

[Incubus]

I actually really liked the schnorkel. From what I observed, it allows you to get, with upgraded engines, nearly the initial standard surface speed. Also, you can get away with going a little deeper than 'schnorkel depth'. I don't know if the game models the added stealth, but by going about 1-2 meters deeper, it decreases the wake considerably.

[gutted]

if you don't use your snorkel much.. then you obviously dont use your hydrophones all that much to find stuff that BDU doesn't report to you.

the snorkel is a blessing for listening on the move.

[Sailor Steve]

Originally Posted by Incubus

I actually really liked the schnorkel. From what I observed, it allows you to get, with upgraded engines, nearly the initial standard surface speed. Also, you can get away with going a little deeper than 'schnorkel depth'. I don't know if the game models the added stealth, but by going about 1-2 meters deeper, it decreases the wake considerably.

In real life subs couldn't make any more than standard submerged speeds using the schnorkel; the pole could snap off under the pressure of higher speeds. Also, in even the slightest sea the water would wash into the opening, causing the float to close, causing the engines to suck all the air out of the boat, causing an emergency surface to get air to the suffocating crew.

In addition, at least one schnorkeling u-boat was spotted because an alert destroyer lookout saw diesel smoke coming out of the water!

Also, upgraded engines are very unhistorical; all type VIIb and later boats had superchargers, and the 'regular' top speeds in the game are actually the speeds they made with superchargers.

The game lets you get away with a lot of crap.

[melnibonian]

Schnorkel is great. It is very useful as you can go at high speeds submerged and you avoid planes and DDs. I have been bombed a couple of times while at schnorkel depth (I wasn't using the scope so I had no warning) but once it is available I always install it in my boat. In real life according to the book 'Iron Coffins' it took a long time to fit it to the whole fleet with grim results for the german U-Boat fleet. It was a brilliant design but it arrived too late to make any real difference.

[I-25]

Originally Posted by Sailor Steve

In real life subs couldn't make any more than standard submerged speeds using the schnorkel; the pole could snap off under the pressure of higher speeds. Also, in even the slightest sea the water would wash into the opening, causing the float to close, causing the engines to suck all the air out of the boat, causing an emergency surface to get air to the suffocating crew.

In addition, at least one schnorkeling u-boat was spotted because an alert destroyer lookout saw diesel smoke coming out of the water!

Also, upgraded engines are very unhistorical; all type VIIb and later boats had superchargers, and the 'regular' top speeds in the game are actually the speeds they made with superchargers.

The game lets you get away with a lot of crap.

Someone Should mod this:hmm:

[andy_311]

I won't have it so I select none but for some reason even when I select no snorkal I seem to have it dead weird.

[The Munster]

The best time to use the Schnorkel is in 'flat calm'

[con20or]

Ive brought this up a few times, but I never get a convincing answer and there always seems to be alot of disagreement.

How does your lookout function while you are running at some high Time Compression??

As the original poster says, the first warning of being spotted is DC's falling around you. Obviously this is a bit rubbish, as IRL they would have had someone manning the observation scope (and attack scope?).

I was told something b4 about the only warning you get is that the TC drops. Its a shame you cant raise the scope and assign crew to watch.

Or can you?

[The Munster]

I find once you go past x128 Compression, your Watch section is practically disabled i.e. the Liberator has swept over you and dropped two big ones or the Hunt has arrived and started pounding you with depth charges before you know it.

[Lzs von swe]

I use the schnorkel as much as possible, going at pd in calm seas. But any rougher sea then that will have your engine crew running back and forth between the engine rooms as the diesels cuts out when the schnorkel "drowns". And going at pd in rough seas will expose the conning tower for enemy radar.

I read somewhere about U-boats going for many days submerged, I probably remember wrong but up to 50 days, getting all sorts off problems with the systems onboard due to the extreme humidity, not to mention how the crew felt.

[Steeltrap]

Cremer in U-333 commented that the schnorkel was very valuable. The 'float closing' mentioned used to cause unpleasant pressure changes in the boat, but not to the extent of having to surface or anything of the like (probably because skippers knew when the sea was too rough to function).

[Hartmann]

I like the snorkel because is the only way to survive at the end of the war, when stay at surface makes you a sitting duck for a planes or hunter killer groups.

I think that one way to use the snorkel is stay at low speed patrolling during the day and raise it at night to recharge the batteries.this hide the smoke at makes difficult for the planes spot the snorkel.but by the other hand makes difficult spot the incoming planes...

All the tactics are different, and the submarine becomes very limited with a reduced sumerged speed. no more chases at flank speed in the surface, now is wait for a incoming convoy that make possible a low speed interception course.

It makes the XXI the ideal boat in the late war , 17 knts sumerged ...snorkel radar detector.., and other luxurious details compared with the VII ,IX.

[Ducimus]

Snorkel cons:
- 3cm radar. That is what gets you an ashcan on your wintergarden.
- It's loud.
- It's an admission of defeat. Only when your forced to remain submerged all the time do you truly realize that the uboat is NOT a submarine, but a submersible dependant on the surface for both replenishing oxygen/batteries, and for attacking or gaining a firing position.

Pro's:
Your odds of survival increase greatly.


Personnal recommendations:
- Try one of the snorkel "fixes" which basicially gives the radar a min hieght of 1 meter off the surface of the water.

- Snorkel ONLY to recharge battiers when needed, and establish a routine. For example id only run the snorkel at 0 hour and would lower the mast immediatly as soon as the batters were fully recharged. Usally around 0500. Chances of airstrikes at night are *slighly* less.

[panthercules]

Originally Posted by gutted

if you don't use your snorkel much.. then you obviously dont use your hydrophones all that much to find stuff that BDU doesn't report to you.

the snorkel is a blessing for listening on the move.

??

Not sure exactly what this means - what does the schnorkel have to do with hydrophone checks? When I'm conducting routine hydrophone checks (which I do, as the term implies, rather routinely), I always do it at dead slow or all-stop, since at any higher speeds the noises from my own boat's engines/props would tend to drown out any more distant screw noises I might otherwise detect, and I always do it at about 20m depth, as that appears historically to have been more or less optimum depth for such checks. I would assume that running on diesels using the schnorkel would be way louder than on electrics (or stopped), plus you'd be closer to the surface (where surface/wave noises would be increased, thus also masking the more distant screw noises). Therefore, I would not think that the schnorkel would really be "a blessing for listening on the move".

Thanks for all the input folks - sounds like Ducimus pretty much summed up where I was coming out on this:

Originally Posted by Ducimus

Snorkel ONLY to recharge battiers when needed, and establish a routine. For example id only run the snorkel at 0 hour and would lower the mast immediatly as soon as the batters were fully recharged. Usally around 0500. Chances of airstrikes at night are *slighly* less. .

And I certainly agree with what seems to be the consensus opinion that while the schnorkel may thus provide some additional chance of survival, it basically was too little/too late and was an admission that the U-boat had failed in its essential mission 'cause it could no longer really function as it needed to in order to accomplish any meaningful result in terms of affecting the outcome of the war.