I have a question about Destroyers and Depth charging

Bribarian · 12-17-09, 02:24 AM

One thing I've always noticed is the Subs get most of the attention, which is fine since they are absolutely badass.

But I sometimes wonder about the destroyers too.

One of my questions is how did a destroyer know whether or not it was hitting a sub or even sinking one? How could they tell if their charges were being effective, or did they?

Dowly · 12-17-09, 10:43 AM

They couldnt know for certain, but by listening via hydrophones they could hear noises that would indicate the submarine has been damaged and is sinking (hissing, clanking, twisting of metal, metal hitting the bottom etc.) and another way would be visually scanning the sea surface for any wreckage and oil the submarine could've spilled when damaged.

Welcome aboard.

Raptor1 · 12-17-09, 10:59 AM

I seem to recall that when a depth charge explodes, it causes disturbances in the water that make sonar ineffective for a relatively long time, so it would be quite difficult to determine a kill immediately after a depth charging.

Dowly · 12-17-09, 11:14 AM

Quote:

Originally Posted by Raptor1

I seem to recall that when a depth charge explodes, it causes disturbances in the water that make sonar ineffective for a relatively long time, so it would be quite difficult to determine a kill immediately after a depth charging.

That is true. The destroyer is blind for minutes after the attack run. I remember listening to some audio clip from tests how depthcharge affects hydrophone and some of the explosions could last as long as 60 seconds.

Here's a great site with lots of audio clips (I think the clip I mentioned is somewhere there) from hydrophone training and some from real attacks:
http://www.hnsa.org/sound/index.htm

Sailor Steve · 12-17-09, 02:01 PM

Part of the problem was the sonar itself. It could only look down about 45 degrees, so when the destroyer made its attack run it was effectively blind. They didn't have a precise knowledge of the sub's depth, and they had to speed up to keep the blast from the depth charge from damaging their own ship. Then, because of the 45-degree angle problem they had to get far enough away to make it work again - it would take a minute or so to turn around completely, and then they would still be so close that the sub would be under the sonar angle. So they had to steam far enough away, which took more time, and by then the sub could have turned in any direction.

The coming of Johhny Walker's hunter/killer tactics changed that. Several destroyers fanned out in a line, and the one that found the sub first slowed down and shadowed him, directing the others in for the attack. Losing contact due to water disturbance from the depth-charging didn't matter as much, since the sub was still in front of the 'hunter' when the water cleared again. It couldn't maneuver enough to get away in just one or two minutes.

But the answer to the original question is correct. Some of the time they claimed 'kills' on subs that had actually gotten away, and some of the time they reported a questionable attack and made no claim, when in reality that u-boat never reported back to BdU again. Only the careful checking of records after the war cleared up the problems, just as that same careful checking revealed the truth about the u-boats' claims for sunken merchants. A lot of the time they didn't know either.

Weiss Pinguin · 12-17-09, 06:19 PM

Yep, it seems like it was a touch and go business, confirming a kill... It might be interesting if Ubisoft 'modeled' that in SH5...

Torplexed · 12-17-09, 09:13 PM

According to captured Japanese records, the Imperial Japanese Navy believed their escorts sank about 468 US submarines during the course of the war. That's about twice as many as were built.

Bribarian · 12-18-09, 05:11 AM

I always wondered what went through a destroyer captain's mind early on in WW2, when they practically had no way of really knowing what was happening. Must have been nervewrecking.

Sailor Steve · 12-18-09, 06:32 PM

Don't know about the Japanese, but the British were doing alright. They had actually pioneered depth-charging toward the end of WW1, and were leading the pack in Sonar technology. Their biggest problem was lack of ships to actually cover the areas needed. The 'V&W' class from SH3 were actually two separate classes built in 1918. It took them quite some time to get the corvettes built and into action.

Yes, they were worried, but they scored some big victories fairly early on.

vedrand · 12-20-09, 03:03 PM

Quote:

Originally Posted by Dowly

Here's a great site with lots of audio clips (I think the clip I mentioned is somewhere there) from hydrophone training and some from real attacks:
http://www.hnsa.org/sound/index.htm

Oh oh this is such a treasure!

tigone · 01-12-10, 03:29 PM

The mid-war introduction of hedgehog helped in two ways. First, it threw the weapon ahead of the attacking ship, allowing the escort to remain in sonar contact right up to the point of firing (or nearly so), and second, the charge exploded on contact, not at a specific depth. So if you were attacking a target in deep water, any detonation could be assumed a "hit." And because hedgehog was a contact weapon, even a relatively small explosion right up against the hull was often enough to kill the sub outright.

CaptHawkeye · 01-18-10, 11:11 PM

It's worth noting that despite the introduction of the Hedgehog and later Squid ASW systems, Depth Charges remained the primary means of attacking submarines throughout the war and attained the greatest number of kills by the end.

The escorts held the line against the Wolf Packs for years. But what really led to the destruction of the Kriegsmarine was Aerial ASW. Performed by long range bombers and Escort Carrier hunter-killer groups. Eventually once the Allies had amassed enough Air Power in England they were able to effectively shut down Axis Ports in France and Italy as is. By 1944 most German Submarines were being sunk before they could even leave port.

12-17-09, 02:24 AM	#1
Bribarian Swabbie Join Date: Dec 2009 Posts: 11 Downloads: 0 Uploads: 0	I have a question about Destroyers and Depth charging One thing I've always noticed is the Subs get most of the attention, which is fine since they are absolutely badass. But I sometimes wonder about the destroyers too. One of my questions is how did a destroyer know whether or not it was hitting a sub or even sinking one? How could they tell if their charges were being effective, or did they?

12-17-09, 10:59 AM	#3
Raptor1 Navy Seal Join Date: Jul 2007 Location: Stavka Posts: 8,211 Downloads: 13 Uploads: 0	I seem to recall that when a depth charge explodes, it causes disturbances in the water that make sonar ineffective for a relatively long time, so it would be quite difficult to determine a kill immediately after a depth charging. __________________ Current Eastern Front status: Probable Victory

12-17-09, 02:01 PM	#5
Sailor Steve Eternal Patrol Join Date: Nov 2002 Location: High in the mountains of Utah Posts: 50,369 Downloads: 745 Uploads: 249	Part of the problem was the sonar itself. It could only look down about 45 degrees, so when the destroyer made its attack run it was effectively blind. They didn't have a precise knowledge of the sub's depth, and they had to speed up to keep the blast from the depth charge from damaging their own ship. Then, because of the 45-degree angle problem they had to get far enough away to make it work again - it would take a minute or so to turn around completely, and then they would still be so close that the sub would be under the sonar angle. So they had to steam far enough away, which took more time, and by then the sub could have turned in any direction. The coming of Johhny Walker's hunter/killer tactics changed that. Several destroyers fanned out in a line, and the one that found the sub first slowed down and shadowed him, directing the others in for the attack. Losing contact due to water disturbance from the depth-charging didn't matter as much, since the sub was still in front of the 'hunter' when the water cleared again. It couldn't maneuver enough to get away in just one or two minutes. But the answer to the original question is correct. Some of the time they claimed 'kills' on subs that had actually gotten away, and some of the time they reported a questionable attack and made no claim, when in reality that u-boat never reported back to BdU again. Only the careful checking of records after the war cleared up the problems, just as that same careful checking revealed the truth about the u-boats' claims for sunken merchants. A lot of the time they didn't know either. __________________ “Never do anything you can't take back.” —Rocky Russo

12-17-09, 06:19 PM	#6
Weiss Pinguin Ocean Warrior Join Date: Nov 2008 Location: Auburn, Alabama Posts: 3,333 Downloads: 101 Uploads: 0	Yep, it seems like it was a touch and go business, confirming a kill... It might be interesting if Ubisoft 'modeled' that in SH5... __________________

12-18-09, 06:32 PM	#9
Sailor Steve Eternal Patrol Join Date: Nov 2002 Location: High in the mountains of Utah Posts: 50,369 Downloads: 745 Uploads: 249	Don't know about the Japanese, but the British were doing alright. They had actually pioneered depth-charging toward the end of WW1, and were leading the pack in Sonar technology. Their biggest problem was lack of ships to actually cover the areas needed. The 'V&W' class from SH3 were actually two separate classes built in 1918. It took them quite some time to get the corvettes built and into action. Yes, they were worried, but they scored some big victories fairly early on. __________________ “Never do anything you can't take back.” —Rocky Russo

12-17-09, 10:43 AM	#2
Dowly Lucky Jack Join Date: Apr 2005 Location: Finland Posts: 25,005 Downloads: 32 Uploads: 0	They couldnt know for certain, but by listening via hydrophones they could hear noises that would indicate the submarine has been damaged and is sinking (hissing, clanking, twisting of metal, metal hitting the bottom etc.) and another way would be visually scanning the sea surface for any wreckage and oil the submarine could've spilled when damaged. Welcome aboard.

12-17-09, 09:13 PM	#7
Torplexed Let's Sink Sumptin' ! Join Date: Dec 2001 Location: Seattle, WA Posts: 5,823 Downloads: 43 Uploads: 0	According to captured Japanese records, the Imperial Japanese Navy believed their escorts sank about 468 US submarines during the course of the war. That's about twice as many as were built.

12-18-09, 05:11 AM	#8
Bribarian Swabbie Join Date: Dec 2009 Posts: 11 Downloads: 0 Uploads: 0	I always wondered what went through a destroyer captain's mind early on in WW2, when they practically had no way of really knowing what was happening. Must have been nervewrecking.

01-12-10, 03:29 PM	#11
tigone Mate Join Date: Jul 2008 Posts: 56 Downloads: 33 Uploads: 0	Destroyers and Depth-Charging The mid-war introduction of hedgehog helped in two ways. First, it threw the weapon ahead of the attacking ship, allowing the escort to remain in sonar contact right up to the point of firing (or nearly so), and second, the charge exploded on contact, not at a specific depth. So if you were attacking a target in deep water, any detonation could be assumed a "hit." And because hedgehog was a contact weapon, even a relatively small explosion right up against the hull was often enough to kill the sub outright.

01-18-10, 11:11 PM	#12
CaptHawkeye Weps Join Date: Mar 2008 Posts: 354 Downloads: 1 Uploads: 0	It's worth noting that despite the introduction of the Hedgehog and later Squid ASW systems, Depth Charges remained the primary means of attacking submarines throughout the war and attained the greatest number of kills by the end. The escorts held the line against the Wolf Packs for years. But what really led to the destruction of the Kriegsmarine was Aerial ASW. Performed by long range bombers and Escort Carrier hunter-killer groups. Eventually once the Allies had amassed enough Air Power in England they were able to effectively shut down Axis Ports in France and Italy as is. By 1944 most German Submarines were being sunk before they could even leave port.