Anti-Destroyer tactics - Page 2

November 14th, 2008  
I stand by my earlier statements. Anti destroyer warfare was avoidance. Subs would leave destroyers alone. If you prioritize all the ship types a sub would engage the last one on the list would be destroyers, right after row boats.

WWII and earlier submarines were small and had limited space for weapons. Carrying defensive weapons reduces the number of offensive weapons they could carry. Basically these subs carried around twenty torpedoes. They did not have extra space. Carrying Anti Destroyer weapons would reduce this number and their ability to carry out their primary mission. I am not saying that subs wouldn't fight a destroyer only that it would be an act of desperation.

In a way you could relate a sub to the school yard bully. They would rather pick on someone who wouldn't or couldn't fight back. Bullies don't pick on those who fight back because they could loose.

WWII subs running submerged on batteries had limited speeds and duration. They could not afford to get in a fight with a destroyer that could hang around indefinitely. Destroyers can't hear in about a thirty degree angle to the stern. To counter this destroyers turn quickly and often. A sub getting in the baffles of destroyer would have the opportunity to escape, or fire a torpedo (giving away it's position), would try and escape.

"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." quote mmarsh.

Interesting, but I would have to see the directive to believe it. As the US was fully engaged in cutting off supplies to Japan. The midnight express runs of trying to resupply the Japanese (on various islands), would still make stopping the supplies the priority.
December 19th, 2008  
Mark Conley
Maybe this letter from Fleet Admiral King written at the end of WW ii might sum it up in regards to how he felt about submarines and the effectiveness against non-comerce type vessals.

The first time i ever heard of the desperate act of what is reffered to as a "down the throat" shot was Cmdr Morton and USS Wahoo during its 3rd war patrol after 16 Jan 1943.. This is a partial description of the event.

"Thoroughly alerted by the white torpedo wakes scarring the surface, HARUSAME bore down on WAHOO. With nothing but mud beneath their keel, Morton ordered the periscope raised and O’Kane called out the range. Firing his last bow tube down the destroyer’s throat from 800 yards, Morton took WAHOO to 90 feet to await its short run. Most of the crew anticipated their own demise.
Seconds later a devastating explosion was heard through the hull. Raising the periscope, O’Kane exclaimed that HARUSAME was broken in two and settling by the bow."

A down the throat works by closing to extremely short range (say 800-600 yards) and firing the torpedo (two works better) directly at the bow. Its takes the destroyer a little bit of time to realize its got one comming down the bow, as both objects (ship and torp) are closing the range quickly between each other, and sometimes the subs wake will disguise the speeding little gift coming at you. If the destroyer stays on gets it in the bow. If the destroyer turns left or may not turn fast enough to prevent the sides of the boat from getting hit, especially in the rear. Mortons destroyer tried to turn and got hit in the side, hence the broken in two scenario.

It was well known that the US Navy labeled all japaneese destroyers as priority targets in in 1944. One boat that took up Japanese destroyer hunting in a big way was USS Harder .Her skipper, the resolute and resourceful Commander Samuel D. Dealey, "a submariner's submariner," was posthumously awarded the Medal of Honor. In some books he took down 5 destroyers in 3 days: in others four in 3 days. even wounding a destroyer was bad, for it took it away from escort duties, and thats what you wanted: a good shot at the goodies without dying from the escorts. the thing was, he went after the escorts with this in mind: no more escorts for the frieghters, it was going to be good to get them with other subs in the areas when working as a wolf pack.

Of course, the japaneese did not have hedge hog rocket fired anti submarine charges either, so deliberatly tangling with a destroyer had a different outcome the say german sub vs US destroyer.
December 20th, 2008  
Mark, Interesting stuff. Something else that occurs to me is if a sub could launch a spread of torpedo's say 7-8 in rapid succession. One would be directed directly at the destroyer forcing it to turn. 2 would be directed to either side but nearly head on, say at about +/- 2 degrees. 2 more would be directed at +/- 5 deg and 2 at +/- 10 degrees. The idea is as the ship turns to avoid it will expose more of its hull.

Problem is I think the torpedo tubes point in the same direction, so the sub or the torpedo's would have to be modified. In the latter case a gyro adjustment may be all that is necessary. The torpedo's would be specialist for this purpose and of course designed to run near to the water line and detonate on a glancing blow. I doubt if it would take much to sink a destroyer.
December 20th, 2008  
Mark Conley
Down the throat shots are unique...the most you would want to throw at a vintage WWII destroyer would be 3. one aimed directly at the bow and the other 2 diverging slightly to get him in the side. if he's stupid enough to try and violently turn left or right hes toast. stays on course..he's toast.

The bad thing was, at this time of the War in the pacific, it was bad torpedos. you threw enough at one target to make up for the lousey performance. one torpedo was enough to sink a destroyer...if it went off. but you didnt take chances. a common spread was 3-4 at one target. most captains carried 24 torpedos. there were so many in the front, and so many in the back (yes fleet subs had two torpedo rooms.) you had to think of utilizing the front and rear to get the most from your load.

one trick was to lure the destroyer for a down the throat shot by running away but leaving the scope up for a reference point. sort of luring that big boy on, when you had a bad time planned for him. when he got close enough to not avoid the shot, you sent two on their way from the rear. now, you only tried this if there was only one destroyer in the vacinity. two destroyers could ruin your whole day.
December 21st, 2008  
Originally Posted by Mark Conley
you only tried this if there was only one destroyer in the vacinity. two destroyers could ruin your whole day.
Yes, but of course there must have been more situation's where the submarines outnumbered the escorts especially if the destroyers were scattered along the whole length of a convoy. I would have expected this would provide opportunities for an adjacent U boat to attack the destroyer attacking a fellow U boat.

I suppose the early U boats were essentially surface vessels that could dive, but had little manoeuvrability once reliant on their batteries underwater. The later types however were a different matter.
December 21st, 2008  
Originally Posted by perseus
mmarsh Yes, I forgot about the acoustic torpedo. Didn't the Allied ships use a decoy acoustic signature to deflect the torpedo?
The British did have a device, I forget what it was called but essentially they were noisemakers that were towed behind the destroyer to throw off acoustic torpedoes

However it was a double-edged sword because using such devices made the destroyer more easily detectable to the U-boats Hydrophones operator and could therefore announce the presence of a convoy to a Uboat, which negated a convoys biggest defense remain undetected.

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