Artist's commentary says that the third girl is Bismarck, changing tags accordingly.

Sweet backflipping Christ on a unicycle, those are some lovely ladies! I think it'd have been better with a British ship like Warspite instead of an American one like Iowa, it'd have been a fully European blue-eyed blonde girls trio. Oh well, I can't really complain, sweet and beautiful Richelieu is center stage.

I can see Richelieu as Aglaea (the youngest and the personification of beauty), Iowa as Thalia (the personification of abundance) and Bismarck as Euphrosyne (the personification of joy).

Fun fact, Lucas Cranach the Elder painted several versions of "The Three Graces", as seen here: https://en.wikipedia.org/wiki/User:Jane023/Paintings_by_Lucas_Cranach_I. I think there's also a fourth one, but it's not listed.