Caramba, like myself you probably have so many questions you could ask only it's too late. You might like to read the memories of my long-gone friend Bob Hume, who trained as a flight engineer at Pembroke Dock in 1943 and perhaps even met your father. By the way, there's an excellent Sunderland museum in the old chapel at Pembroke Dock which you would enjoy visiting.
https://www.sunderlandtrust.com/
Bob remembered takeoffs as being exciting, as in calm conditions a Sunderland or Catalina at operational weights could take three miles to get airborne. Usually it was between one and two miles. Wind had most effect of course, but calm water increased suction on the hull due to the Bernoulli effect. In such conditions a couple of launches would zig-zag across the fairway to roughen it up, a task exciting to the boat crews and to the anxious aircrew in the Sunderland thundering towards them at 40 knots or more.
The flying-boats began their run by 'ploughing' through the water with the stick fully back until the nose rose and the bow-wave began moving aft. In calm conditions it helped to pump the stick gently to encourage this. At this stage the stick was eased forward to encourage the hull to rise onto its step and begin planing at around 50 knots, so decreasing the water drag and enabling the craft to attain flying speed. Of course there were no powered controls so pilots had to be pretty fit.
Bob recalled that they would often taxi a couple of miles along Milford Haven before takeoff, while for certain wind conditions they used an area off Angle, several miles away, and were sometimes towed by boat to save fuel, adding an hour or more towage each way to a typical 12 hour sortie.
Bob and his colleagues liked their sturdy Sunderlands although their 965bhp Bristol Pegasus engines sometimes gave trouble because they were consistently overworked and had two-speed VP propellers. The Sunderland V had 1200bhp Twin Wasps and constant-speed props as used in Catalina, Dakota and Liberator, enabling the big boat to maintain height on two engines.
During their long patrols Bob's skipper encouraged his crew to interchange their duties in case of emergencies. Twenty-three years later I took Bob aloft again to make him one of the few pilots to transition to Tiger Moth after 20 hours ab-initio in a Sunderland, and very well he managed it.
Despite hundreds of hours on Atlantic patrol, Bob and his crew saw no action although in early 1944 they did sight a Kurier circling a convoy about 100 miles out from Donegal. “We were all dead keen to have a go, the skipper turned towards it and we opened the Peggies flat-out though we had no chance of catching it, maybe we thought we could sneak up on him. The nav was up in the astrodome giving a running commentary: he's going left, no he's going right, dammit he's turning south, the ------'s running away!
I don't blame him, said the skipper, the first time I saw you lot forming up at OTU I felt like doing the same thing.