Anti-Destroyer tactics




 
--
 
October 14th, 2008  
perseus
 
 

Topic: Anti-Destroyer tactics


Has anyone heard of submarines during WW1/WW2 using offensive tactics as a means of defence against destroyers? I vaguely remember a report of a submarine firing a torpedo directly at a closing destroyer head on. Since depth charges had limited range, and shells would just ricochet of the top of the water, it would seem that a partly submerged submarine at periscope depth would have the first shot. Failing this it would seem relatively straightforward to design the submarine to release some mines across the destroyers path as it retreats away under battery power. Perhaps I am missing something obvious here but surely this sort of tactic may have rendered escorts redundant at a stroke?

As far as I know the direct attack was the only means available to a destroyer in the first half of the 20th Century.

The basic destroyer attack procedure was to point the ship at the target and head towards it at a moderate speed. Once the ship was generally within 1,000 yards, sufficient sonar data regarding the submarine's heading and speed should have been determined. At that point, the destroyer's helm would maneuver on a "collision course" with the target. Adjustments would be made in the DD's course to account for the approximate depth of the sub, calculating the amount of time it would take for a depth charge to sink to the lethal level. Depth charges dropped from the stern tracks would be in evenly spaced intervals. The port and starboard throwers would send DC's approximately 50 yards out on either side - forming an elongated diamond shaped pattern. The goal was to pass just far enough ahead of the submerged target and launch the DC's in the hopes that the submarine's travel would take them right into the path of the sinking ordnance.

http://www.valoratsea.com/destroyer.htm
October 18th, 2008  
LeEnfield
 
 
Shooting head on at a destroyer only gives the U Boat caption a very small shot, a destroyer is not much more than 30 feet wide. This tactic was greatly extolled by Hollywood in many of the films about American Subs in the Pacific.
U Boat captain doing this manoeuvre would lay him self wide open to an attack with the hedgehog
October 19th, 2008  
perseus
 
 
LeEnfield

Yes, I suspected Hollywood was responsible for this idea, however the submarine would have several shots. I recall those 'depth charge' games where a submarine can release a buoyant charge that floats upwards to the surface to destoy a ship like a mine. Is this another fantasy or does it have some basis in fact? It seems relatively simple procedure for a sub to release an array of these floating mines in front of the destoyers path.
--
October 19th, 2008  
LeEnfield
 
 
Very few Submarines could release mines under water, the very few submarines that carried mines carried very few torpedo's. Where as the destroyers were equipped during the war with the Hedgehog. The Hedgehog threw large mortar type bombs ahead of the destroyer in a pattern that would hit most subs. the idea was that they would only explode on contact, so if they did not hit any thing it would disturb the water and the destroyer would not lose sonar contact, so the chase could continue.
October 19th, 2008  
perseus
 
 
Well yes, the hedgehog was only deployed from 1943, before that they used conventional depth charges which had a very low success rate. However, the sort of tactic I envisage was that the submarine lays a large number of small mines between itself and the advancing destroyer to form a screen. Obviously subs would have to be adapted for this but technically it seems an obvious defense tactic. The mines could even be drawn behind the sub using cables.
October 19th, 2008  
LeEnfield
 
 
The mine laying subs would release the old horned type mined which would be anchored to the sea the sea bed. They mainly used this type of sub on estuaries as they could slip in and out with out being seen and they stood a greater chance of hitting some thing
November 12th, 2008  
Chukpike
 
I believe there is a basic misunderstanding in this topic. Anti Destroyer warfare for the subamrine was basically avoidance. To stay hidden. The firing of a torpedo was usually the first indication that a submarine was close.

Submarines primary mission was to destroy high value targets. Those being supply, or oil tankers, or troop ships. Wasting a torpedo on a destroyer defeats the submarines mission. The destroyer wins in that scenario. Remember the mark of sucess for submarines was in the tonnage of ships they sank.

Submarines had a limited amount of weapons and would have to withdraw when these were expended.

Destroyers lose the battle when they are not able to protect the ships under their support.

Anti-submarine doctrine actually directs destroyers to maneuver to take a hit from a torpedo rather than allow it to hit a higher value target. The Captain of my ship was less than enthused about this directive. Submariners new this and could set the run depth of their torpedoes to pass under a destroyer and continue to its target.

Simple example: Destroyer's draft less than 20ft. Supply ships draft more than 20ft.

Run depth of a torpedo was always a consideration for submariners. To shallow and wave action could effect its ability's to run straight. Set to deep and it could pass under its intended target. Remember WWI and WWII torpedoes were mostly contact weapons and not guided.

Submarines always have an advantage over destroyers as they can hear a destroyer's active "pinging" at at least twice the range that it would take the destroyer to get a return from it's signal. All surface ships make considerably more noise than a submarine running submerged. Avoidance was easy.

I was a destroyer sonarman for 6 years during the early 1970's.
November 13th, 2008  
perseus
 
 
Thanks for your comments Chukpike. I'm aware that it is normal doctine to avoid detection from surface ships but I'm just trying to think out of the box here and say what would happen if the designers of submarines (in WW2 not post war) tried to introduce measures to attack the destroyers attacking them? The attack method of the destroyers in the early years was very basic, simply drop a large timed charge over the submarine and most attacks of this kind were unsuccessful.

It seems to me that there are a number of possibilities here for the submariner, either to release a spread of specialised torpedoes ones which operated near to the surface when the destroyer is nearly upon them, or to release a spread of mines which float to the surface thereby causing the destroyer to swerve. There are many more sophisticated variations on these ideas, and I except the innovative Germans must have thought about these and dismissed them.

Sorry I think more like a designer/engineer rather than an operations person who has to make do with what he has got!
November 13th, 2008  
mmarsh
 
 
Quote:
Originally Posted by perseus
Thanks for your comments Chukpike. I'm aware that it is normal doctine to avoid detection from surface ships but I'm just trying to think out of the box here and say what would happen if the designers of submarines (in WW2 not post war) tried to introduce measures to attack the destroyers attacking them? The attack method of the destroyers in the early years was very basic, simply drop a large timed charge over the submarine and most attacks of this kind were unsuccessful.

It seems to me that there are a number of possibilities here for the submariner, either to release a spread of specialised torpedoes ones which operated near to the surface when the destroyer is nearly upon them, or to release a spread of mines which float to the surface thereby causing the destroyer to swerve. There are many more sophisticated variations on these ideas, and I except the innovative Germans must have thought about these and dismissed them.

Sorry I think more like a designer/engineer rather than an operations person who has to make do with what he has got!
------------------------------------------------------------

Starting in 1942, The Germans developed two Torpedoes known as TIVb Falke and the TVe (Wren). 'Falcon' and 'Gnat' in English.

These two torpedoes were specifically designed to disable Destroyers. I say disable not Destroy because they were both acoustic fish with relative slow speeds, short range, and small warheads and since they homed in on the propellers and not somewhere more vital, a hit was usually non-fatal.

The Torpedo was generally loaded in the aft tube(s) on the Type VII and Type IX. The tactics the Germans developed was to allow the target to pass behind the Uboat (usually after a depth charge Run) then fire the fish as the destroyer passed by as the acoustic sounds would be strongest and the close range gave a good chance of a hit.

This was typically used to escape a attacker as a hit usually meant the Destroyer would be dead in the water allowing the Uboat either escape or a easy target.

Changing theatres. In 1944 US Naval Intelligence figured out that over the 3 year war the Japanese had lost most for their destroyer force, so US Submarines were ordered to consider IJN Destroyers as priority targets (above Marchant ships) as they wanted to completely eliminate Japans ability to protect their Midnight Express runs.
November 13th, 2008  
perseus
 
 
mmarsh Yes, I forgot about the acoustic torpedo. Didn't the Allied ships use a decoy acoustic signature to deflect the torpedo?
 


Similar Topics
House Panel Reconsiders Development Of New Destroyer
N. Korea Test-Fires Missiles As South Launches U.S.-Equipped Destroyer
Miami Party To Precede Commissioning Of Navy Destroyer
JI changing tactics just in time for the holiday season
Mongols.