Convoys?

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From Wiki about Adm E King :
At the start of US involvement in World War II, blackouts on the U.S. eastern seaboard were not in effect, and commercial ships were not travelling under convoy. King's critics attribute the delay in implementing these measures to his Anglophobia, as the convoys and seaboard blackouts were British proposals, and King was supposedly loath to have his much-beloved U.S. Navy adopt any ideas from the Royal Navy. He also refused, until March 1942, the loan of British convoy escorts when the Americans had only a handful of suitable vessels.
 
In King's defence, he was right to some degree in that the US Navy did not have sufficient escort vessels to protect convoys, and collecting ships together in a convoy without adequate or any escort is not clever?
 
vinnye said:
In King's defence, he was right to some degree in that the US Navy did not have sufficient escort vessels to protect convoys, and collecting ships together in a convoy without adequate or any escort is not clever?
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There was some work done by statisticians that showed that even an unescorted convoy cut losses. The fact is a sub has a very limited search area with a horizon of about 12 miles with a steady stream of say 1 ship per hour or two all a sub has to do is sit and wait for the target. If suddenly its only say 1 convoy per 72 hours then a sub has to move about looking for it unless it sits at a choke point which will be patrolled. King tried to justify himself after the war and most contemporary critics thought he didnt do a very good job.

The USN and USAAF had enough aircraft to put 1 a/c over each convoy during daylight hours it just needed someone to co ordinate things. Kings problem is he seemed to hate everyone and worked very poorly with different forces.
 
A lot of results of operations research are counter-intuitive, with the benefits of unescorted convoys vs ships sailing alone being one of them. Fastmongrel has one part of the equation; here's the other bit.

Say a single ship can be spotted because of smoke at 20 nautical miles, and a convoy of 100 ships can be spotted at twice the distance. Say the sea routes between North America and Britain have a total area of 2,000,000 square miles. The convoy can be spotted in an area of about 500 square miles; the single ships each in an area of 125 square miles. However, the 100 ships have a total area where they can be spotted of 12,500 square miles: 25 times greater. Or let's say that each ship has a 0.001 chance of being spotted (1 chance out of a thousand) and the convoy has a 0.01 chance of being spotted. Assuming each ship/submarine encounter is independent, that means that the probability of no ship getting spotted is roughly (1-0.001)^100 or about 90%, i.e., there's a 10% chance of at least one ship being spotted, vs 1% chance for any of the ships of the convoy to be spotted.

Similar non-intuitive results are that landplanes are better for MPA than seaplanes and that the number of casualties is increased by heavy defensive armament in bombers.
 
1 March 1941.
Support Force Atlantic Fleet established for protection of convoys in North Atlantic.
After this date we began escorting British merchant convoys in the Atlantic.

17 Oct 1941.
USN orders all U.S. merchant ships in Asiatic waters to put into friendly ports.
After this date U.S. shipping west of Hawaii was by escorted convoy. 100,000 or so tons of cargo per month was transported to Philippines this way during fall of 1941.
 
I'm skeptical if the USN had the equipment or the know how to defend convoys against the most effective tactic of the U-boats against convoys during early 1942. This tactic was to attack on the surface at night. This tactic was deadly effective against convoys in the early way years.

For example a single U-boat, U-100, under command of Joachim Schepke sank more than 50,000 tons of shipping from one convoy in less than four hours using this tactic, while the escorts milled around hopelessly firing star shell. Convoy SC-7 lost 21 ships to four U-boats using this tactic. This was given the title as the "Night of the Long Knives" by the U-boat force.

Active sonar/Asdic was rendered useless by this tactic. Detecting U-boats visually at night among ocean swells was virtually impossible. Early pattern meters wave length radar sets such as Type 286 was virtually useless because of sea clutter.

The British had only within a few months began to equip convoy escorts with an effective means of detecting surfaced U-boats at night (but only to ranges within about 3500 yards.) This was the 10cm Type 271 radar.

American convoy escorts had nothing comparable to Type 271 in early 42. The first few SG sets only became available by mid 42 and those were ear marked for warships deployed to the Pacific. If an American escort vessel had any radar at all during 1942 it would likely have been the almost useless SC.

For U-boat commanders, finding convoys was no problem at all during early 1942, because the Kriegsmarine B-Dienst had broken the Allied merchant marine (and several Royal Navy) wireless codes. British Operational Research had no idea this was how the U-boats were locating so many convoys. They thought it must have been by the U-boats exceptional hydrophones, which they thought effective to 80nm.
 
The USN opposed convoying because it believed it added to shipping needs of the nation, not reduced it. This was despoite all that had been seen in both world wars to that time.

In a sense, compred to peacetime traffic a convoy was innefficient. You could only move at the rate of the slowest ship, you needed to wait a month or more as the convoy forces awere drawmn together, it had to go to a single destinatioon which added to the strains of the local transport network.

philosophically the Americans before the war were firmly wedded to the concept of the decisive battle and resources diverted to defending convoys detracted from that priority. Convoys were seen as essentially defensive, and therefore had no place in USN strategy. Ernie was very much trained in that way of thinking.

And lastly, it was viewed as essentially a British technique, and anything British Unlce Ernie just wouldnt accept. Forget that 80% of losses could be avoided simply by redirection of the convpoy away from the attacking subs operating areas, the Americans needed experience learnt the hard way to drive the benefits of convoy home.
 
It doesnt matter how many escorts a convoy had its still a fact that more than 9 out of 10 convoys got through 100% intact even during the Happy Times for U Boats. Probably a majority of those convoys werent even sighted by a U Boat for the simple reason if you put convoys together the sea becomes empty most of the time. The USN had the example of the RN in WWI on how not to do things in fact USN Adm Sims was a big reason why WWI convoys became so succesful

William Sims - Wikipedia, the free encyclopedia

There was even the experience of the RN in the first few months of the war trying offensive anti sub operations which were about as succesful as the USNs efforts in 42. Theres stupid and then theres stupid in the face of all the evidence to the contrary, the USN had been very succesfully doing convoy duties in the western Atlantic since mid 41 why was that experience and the experience of the RN ignored. A lot of Merchant mariners died within sight of the US seemingly for political reasons.
 
Can't remember where I read it (just recently) that more non convoy ships were sunk than convoy ships.
 
Convoys are less efficient then individual ship sailings. However the fact remains that USA was officially committed to merchant convoys before December 1941. Only thing open to question is USN skill (or lack thereof) at conducting merchant convoys.
 
davebender said:
Convoys are less efficient then individual ship sailings.
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In what sense? Fast merchantmen, under false flags, attempted the run to Malta on several occasions, but were invariably sunk. At least the remnants of some convoys and the bulk of others got through to sustain resistance.

Cheers

Steve
 
steve , i think he means shipping in peacetime. Ships forced to use convoy are much safer, but there is an innefficiency in cargo handling capacity relative to independant sailing. if it wasnt, convoys would also be used in peacetime.
 
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