HELP ??!!?

took an inflatable sup out into some pretty reasonable white water on the wend and it was hopeless...really hard to maneuver...kept spinning around backwards...and everytime it hit an eddy line or side wave water would pour over the rail & it would totally flip...i spent most of my time swimming or seriously under water...

on the internet there are lots of great videos with guys in the states running white water rapids standing up but i havent seen anything in the Oz blogs for people doing this or recommendations for boards to be using...

love surfing as well and before i invest does anybody out there know a suitable board that could meet both activities...am guessing they should have a little in common both needing more stability, volume, rocker, less length , etc but have not seen a recommendation for any boards that would cover both or even anyone talking about white water boards here in Oz..

anyone doing this please let me know...