Translucent material for sails

Hi all

please help me create decent translucent material for sails for my tall-ship. i have tried to mess around with material translucency in UE4 (v4.8.2) but result is quite crazy and looks like this:

thank you

WIP is here:

yes i have tried putting parameter in opacity from 0.96 to 1.0 and result is not changing except sails getting transparent (what expected). i even put 1 in roughness just for tidiness but without results. so, any advice…