Competitive pool swimming as a means to improve marathon swimming
I have noticed the best swimmers in the elite marathon swimming circuit are also the best 1500 m swimmers in the indoor pool, and some of them are also the best in the km race in an 25 m pool dug in the ice.
My local competitive swim clubs don't (currently) do open water swimming, so I'm training in the squad in a small hot pool. Furthermore, due to an incident happened last month I have safety concern about my training and since then have moved all my pool training into heated pools (as I don't have a coach who can coach me in competitive ice swimming - unheated lidos in London are under 5C at the moment - and cold water training isn't needed for both indoor pool swimming and marathon swimming).
Is open water training in a competitive swim club necessary to get a good result in competitive marathon swimming? Or is any pool-based club, combined with triathlon club open water sessions, enough for that?