On 23 Dec 1941 Catalina W8418 of No. 240 Squadron sank at/near RAF Pembroke Dock due to a heavy landing (struck a float?).

There were 6 fatalities (Debonnaire, Havlicek, Lewis, Jones, Gray, Lockett), all named at the Runnymede Memorial. Can I therefore assume that these men could not be recovered anymore from the Catalina, having sunk either too deep in the sea or too far from the coast/station?
If info is available how four more crew (Patterson, Murphy, Westby, Missett) could be rescued, then (also) happy to hear so, thanks.