Snorkelling

[Lt.Fillipidis]

Its a bit odd but when snorkelling, the escorts doesnt seem to hear the boat.
Just like when its on the surface or decks awash. I can run at flank speed without being detected by passive sonar.
Odd...

[Snestorm]

I gave up on SHIII's snorkel. It never worked for me.

1: The CO2 was never replaced by oxygen.
2: The boat was just as detectable while snorkeling as on the surface.

I hope they fix it in SHV.

[RoaldLarsen]

I have successfully replaced CO2 with O2 when snorkeling.

Centimetric radar seems to find snorkeling U-boats just about as well as it finds surfaced u-boats, but I have much more difficulty spotting planes when snorklng than when surfaced. Hence I rarely snorkle.

[Lt.Fillipidis]

I have successfully replaced CO2 with O2 when snorkeling.

Centimetric radar seems to find snorkeling U-boats just about as well as it finds surfaced u-boats, but I have much more difficulty spotting planes when snorklng than when surfaced. Hence I rarely snorkle.

Yeah but you can hear a ship while submerged way before it can detect your snorkel. And in a bit more rough seas, detecting your snorkel touches the limit of impossibility.

[Snestorm]

SHIII screwed up with snorkel so bad that it's safer to surface.

[Randomizer]

Most of my SH3 patrols are late war and so have spent a lot of time snorkelling although I carry few of the objections thrown out here. I spent a fair bit of effort learning how the U-Boats operated inshore in the late war period and applied those techniques to SH3.

1. Snorkelling is not used to transit from Point A to Point B. Use it to top up the battery and air out the boat only.

2. TC and snorkelling means death. Run the game from the navigation map station zoomed to 5000 metres or less with the observation scope raised. Absolute max TC is x32 and you will probably live longer if you limit yourself to x16. When snorkelling you need the map updates to be "On".

3. Never exceed Ahead One-Third when snorkelling, this limits your speed of advance to about 5 kts when charging and no more than 7 kts with standard propulsion.

4. Once you decide it is no longer safe to transit on the surface, cruise submerged at 3 knots and snort two or three times a day or when the battery is down to 85% or so. On station, remain at 2 kts unless prosecuting a contact and snorkelling once a day should be adequate to maintian the battery at >95%.

5. It can take significantly longer to air out the boat and charge the batteries when snorkelling in high seas.

6. Your hydrophones remain effective so SH3 does not appear to model self-noise. Suck it up, the diesels would be shut down regularly to conduct hydrophone checks anyway so who is to say that contact you just detected didn't happen during that time.

7. Contrary to what is often written I do not agree that you are as detectable snorkelling as you are on the surface.

8. Limit your routine cruise depth to <30 m since below that using the heads and disposing of trash through the BOLD tubes becomes problematic.

On my last snorkel patrol (December 1944) I hung around the North Channel for two weeks even spending several days outside Liverpool undetected while sinking three ships and dodging all counter attacks. Unfortunately was sunk hitting a mine in the Hebrides straights on the way home but that wasn't a snorkel problem. Because of the low TC used this patrol took some considerable time to play out but I experianced no game save bug (for saving when submerged) and was careful to save only when out of contact and greater than 50km from a port or more than four-hours game time from a sinking.

Snorkelling in SH3 certainly has issues but using it in a historically reasonable manner while minimizing TC can make your snorting fun again.

Good Hunting

[Weiss Pinguin]

Good tips - I think keeping to historical procedures in general is a good way to minimize bugs and problems

[RoaldLarsen]

Yeah but you can hear a ship while submerged way before it can detect your snorkel. And in a bit more rough seas, detecting your snorkel touches the limit of impossibility.

I don't worry much about surface ships. Only one of my 19 losses has been to a lone warship or a hunter-killer group. Nearly all my losses since late 1942 have been to aircraft. So I am concerned with how detectable the sub is to aircraft.

I agree that the snorkel gets detected too easily in rough seas.

Most of my SH3 patrols are late war and so have spent a lot of time snorkelling although I carry few of the objections thrown out here. I spent a fair bit of effort learning how the U-Boats operated inshore in the late war period and applied those techniques to SH3.

I agree with almost everything Randomizer has written here except:4. Once you decide it is no longer safe to transit on the surface, cruise submerged at 3 knots and snort two or three times a day or when the battery is down to 85% or so.I use 1.8 knots. 3 knots is more realistic, but 1.8 knots is safer.
7. Contrary to what is often written I do not agree that you are as detectable snorkelling as you are on the surface.How much data does Randomizer have to go on? I have run about 40 patrols in snorkel-equipped subs. I'd have to say that detections per unit of time snorkeling is between 75% - 90% of encounters per unit of time surfaced. ("Encounter": my crew sees aircraft; "detection": aircraft attacks me) Given that about 10% of surfaced encounters do not involve the aircraft actually detecting the sub, that means the detections of snorkeling subs occur about 85% - 100% as frequenty as detections of surfaced subs. Tarnmatte can reduce the detections by about 10%, but it wasn't commonly available on operational u-boats.

Against the insignificant improvement in detectability of snorkling over surfaced recharging, one must weigh the the fact that a snorkling u-boat, even with observation scope up, is much less likely to detect attacking aircraft in time to evade attack than is a u-boat surfaced in daylight. This means that a snorkling u-boat detected by aircraft is much more likely to be damaged by those aircraft than is a surfaced u-boat.

If Randomizer has a similar quantity of observations, but different conclusions, could it be because of different areas of operation leading to different aircraft being involved? Not as many of my missions were inshore. Inshore missions seem to run into small aircraft more often and these seem less likely to be equipped with RADAR. I've noticed that single-engined aircraft, though smaller, are more likely to be detected by my crew without the aircraft detecting my sub than is the case for multiple-engined aircraft.

My original comment about detectability specifically mentioned centimetric radar, and most of the attacks on my snorkling u-boats has been by aircraft equipped with centimetric radar. Perhaps detection rates by Hurricanes etc. are signifcantly lower, but I wouldn't have noticed that.

Anecdotally, my most recent trip to the North Channel in 1944 resulted in the loss of my most successful 11th Flotilla commander (7 patrols from 42/10 to 44/05, 163kT sunk). He was attacked by aircraft... while snorkeling.

[Randomizer]

First off it is nice to see another SH3 commander operating in the late war period. I find it far more of a challange to sink 10,000 tons and survive in 1944 than 100,000 tons in 1940 using GWX but to each his own.

RoaldLarson wrote:
How much data does Randomizer have to go on? I have run about 40 patrols in snorkel-equipped subs. I'd have to say that detections per unit of time snorkeling is between 75% - 90% of encounters per unit of time surfaced. ("Encounter": my crew sees aircraft; "detection": aircraft attacks me) Given that about 10% of surfaced encounters do not involve the aircraft actually detecting the sub, that means the detections of snorkeling subs occur about 85% - 100% as frequenty as detections of surfaced subs. Tarnmatte can reduce the detections by about 10%, but it wasn't commonly available on operational u-boats.
I have 25 or 30 late war patrols, all except one were in the shallows of Western Approaches, the North or South Channel, Irish Sea or Western English Channel areas. To be honest I have zero interest in collecting SH3 statistics but consider that my overall success and loss rate after August 1944 compares very favourably with that of the actual inshore U-Boat operations as related by V.E. Tarrant (who uses Rohwer's numbers).

While snorkelling I have frequently spotted aircraft and not been attacked as well as often being attacked by aircraft that were never spotted, both entirely reasonable events. My subjective experiance to date indicates that snorting is best done for short periods when visibility is at its best, allowing the periscope watch a better opportunity to spot non-radar equipped aircraft often found over coastal waters. If the mast-mounted radar detectors detect a signal it's time to vanish and become a hole in the water. Snorkelling in the presence of a known enemy is foolhardy and doing so generally results in a well deserved virtual death and the loss of another boat.

The figure of 3 kts for submerged transits will usually result in a daily run of 70-100 nm, about what was expected of a Type VII snorkel boat according to the few anecdotal accounts from late-war patrols.

My experiance has been that the snorkelling system in SH3 GWX is not as broken as some around here insist but it is not worthy of an arguement.

Late war patrols in the shallows around the UK are tough. Expect few victories and an excellent chance of being sunk but that is what makes them a challange. Historically many of the U-Boats that actually managed to sink something during the inshore campaign were lost soon after and in my opinion SH3/GWX reflects this nasty reality pretty well.

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