I like Iowa, dont get me wrong, but for the battle to get within 10,000yrds, Yamato would have to have started from farther away, and close through its own immune zone, firing the entire way into the close engagement, and most likely hitting Iowa on the way in, diminishing its advantage. The secondary armament, as well as main armament, if damaged would be a huge hinderance to Iowa, and if its vulnerable bow was hit, it would lose the speed, and manouvere advantage it had over Yamato.