● Flying Boats, Seaplane Aircraft

Allies

Catalina - ASW ..

Imperial Airways & Flying Boats .. 

Lockheed Hudson ..

Martin JRM Mars ..

RAF's Flying Boats ..

Axis

● ASW Aircraft ..

Lockheed Hudson ..

● ASW Aircraft

20th 

Avro Shackleton - late '40s ..

Catalina - ASW .. 

21st 

P-8A Poseidon ..

Reconnaissance, ASW, ISR ..

Avro Shackleton - late '40s

Sub Chasers of the Civil Air Patrol > . 
Avro Shackleton - Ecological Bomber in 1971 > . 

The Avro Shackleton was a British long-range maritime patrol aircraft (MPA) used by the Royal Air Force (RAF) and the South African Air Force (SAAF). It was developed by Avro from the Avro Lincoln bomber, which itself has been a development of the famous wartime Avro Lancaster bomber.

The Shackleton was developed during the late 1940s as part of Britain's military response to the rapid expansion of the Soviet Navy, in particular its submarine force. Produced as the primary type equipping RAF Coastal Command, the Type 696, as it was initially designated, incorporated major elements of the Lincoln, as well as the Avro Tudor passenger aircraft, and was furnished with extensive electronics suites in order to perform the anti-submarine warfare (ASW) mission along with a much improved crew environment to accommodate the long mission times involved in patrol work. Being known for a short time as the Lincoln ASR.3, it was decided that the Type 696 would be named Shackleton in service, after the polar explorer Sir Ernest Shackleton.

In April 1951, it entered operational service with the RAF. The Shackleton was used primarily in the anti-submarine warfare (ASW) and maritime patrol aircraft (MPA) roles; it was also frequently deployed as an aerial search and rescue (SAR) platform and for performing several other secondary roles such as mail delivery and as a crude troop-transport aircraft. In addition to its service with the RAF, South Africa also elected to procure the Shackleton to equip the SAAF. In South African service, the type was operated in the maritime patrol capacity between 1957 and 1984. During March 1971, in one high-profile incident, a number of SAAF Shackletons was used to effect during the SS Wafra oil spill, having intentionally sunk the stricken oil tanker using depth charges in order to prevent further ecological contamination.

During the 1970s, the Shackleton was replaced in the maritime patrol role by the jet-powered Hawker Siddeley Nimrod. During its later life, a small number of the RAF's existing Shackletons received extensive modifications in order to adapt them to perform the airborne early warning (AEW) role. The type continued to be used in this support capacity until 1991, at which point it has been replaced by the newer Boeing E-3 Sentry AEW aircraft. These were the last examples of the type remaining in active service.

https://en.wikipedia.org/wiki/South_African_Air_Force

Why Aircraft Patrols Were a Source of Fear for Nazi U-Boats > .
Why Depth Charges Don't Have to Touch a Submarine to Sink It > . 

Avro Shackleton - Wikipedia

Catalina - ASW

Catalina Flying Boat

Coastal Command - ASW
https://youtu.be/uTE-jHVIKJU?t=19m3s

http://www.angelfire.com/fm/compass/Catalina.htm

Short Sunderland, etc - British Seaplanes That Terrorized U-Boats | War Stories > .

Inside The Cockpit - Short Sunderland - MAH > .
Sub Chasers of the Civil Air Patrol > .
Why Aircraft Patrols Were a Source of Fear for Nazi U-Boats > .
Why Depth Charges Don't Have to Touch a Submarine to Sink It > .

Catalina - ASW

Other work by the Coastal Command's Operational Research Section (CC-ORS) indicated that on average if the trigger depth of aerial-delivered depth charges (DCs) were changed from 100 feet to 25 feet, the kill ratios would go up. The reason was that if a U-boat saw an aircraft only shortly before it arrived over the target then at 100 feet the charges would do no damage (because the U-boat wouldn't have had time to descend as far as 100 feet), and if it saw the aircraft a long way from the target it had time to alter course under water so the chances of it being within the 20-foot kill zone of the charges was small. It was more efficient to attack those submarines close to the surface when the targets' locations were better known than to attempt their destruction at greater depths when their positions could only be guessed. Before the change of settings from 100 feet to 25 feet, 1% of submerged U-boats were sunk and 14% damaged. After the change, 7% were sunk and 11% damaged. (If submarines were caught on the surface, even if attacked shortly after submerging, the numbers rose to 11% sunk and 15% damaged). Blackett observed "there can be few cases where such a great operational gain had been obtained by such a small and simple change of tactics".
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"The "exchange rate" ratio of output to input was a characteristic feature of operational research. By comparing the number of flying hours put in by Allied aircraft to the number of U-boat sightings in a given area, it was possible to redistribute aircraft to more productive patrol areas. Comparison of exchange rates established "effectiveness ratios" useful in planning. The ratio of 60 mines laid per ship sunk was common to several campaigns: German mines in British ports, British mines on German routes, and United States mines in Japanese routes."

http://www.feightstudios.com/navalasw.htm .
https://en.wikipedia.org/wiki/Operations_research .

Martin JRM Mars

.Flying Boats & America's Biggest WW2 Plane - The Martin Mars > .

The Martin JRM Mars is a large, four-engined cargo transport flying boat designed and built by the Martin Company for the United States Navy during WW2. It was the largest Allied flying boat to enter production, although only seven were built. The United States Navy contracted the development of the XPB2M-1 Mars in 1938 as a long-range ocean patrol flying boat, which later entered production as the JRM Mars long-range transport.

The Glenn L. Martin Company scaled up their PBM Mariner patrol bomber design to produce the prototype XPB2M-1 Mars. The XPB2M-1 was launched on 8 November 1941. After a delay caused by an engine fire during ground runs, the aircraft first flew on 23 June 1942. After flight tests with the XPB2M between 1942 and 1943, she was passed on to the Navy. The original patrol bomber concept was considered obsolete by this time, and the Mars was converted into a transport aircraft designated the XPB2M-1R. The Navy was satisfied with the performance, and ordered 20 of the modified JRM-1 Mars. The first, named Hawaii Mars, was delivered in June 1945, but with the end of World War II the Navy scaled back their order, buying only the five aircraft which were then on the production line. Though the original Hawaii Mars was lost in an accident on the Chesapeake Bay a few weeks after it first flew, the other five Mars were completed, and the last delivered in 1947.

Four of the surviving aircraft were later converted for civilian use to firefighting water bombers. In 1959, the remaining Mars aircraft were to be sold for scrap, but a Canadian company, Forest Industries Flying Tankers (FIFT), was formed and bid for the four aircraft and a large spares inventory. The company represented a consortium of British Columbia forest companies, and the bid was accepted and the sale completed in December 1959. The four aircraft were flown to Fairey Aviation at Victoria, British Columbia, for conversion into water bombers. The conversion involved the installation of a 6,000 imp gal (27,000 l; 7,200 US gal) plywood tank in the cargo bay with retractable pick-up scoops to allow uploading of water while the aircraft was taxiing. The scoops allowed 30 tons of water to be taken on board in 22 seconds. Later some of the hull fuel tanks were replaced with water tanks.

Two of the aircraft still remain based at Sproat Lake just outside of Port Alberni, British Columbia, although neither are operational.

https://en.wikipedia.org/wiki/Martin_JRM_Mars .