My former instructor and dear friend Sqn Ldr Desmond Mock flew Catalinas from Lough Erne in Northern Ireland. He recalled that the Merlin was highly valued and it wasn't done to admit that coolant leaks were often a problem. He and his colleagues much preferred their pair of P&W Twin Wasps when on an 18-hour Atlantic patrol. I remembered Desmond years later when I was in and out of Scottish Aviation at Prestwick, collecting and delivering parts for overhaul, and more than once saw an ex-Dakota Twin Wasp which had blown off a cylinder head and still kept going as long as all the oil didn't leak away.