Someone help me out on this - what's Yu-12 all about? We have a 21" otto-fuel HWT (Yu-6), a 21" electric HWT (Yu-10 - probably the model that the Vietnamese fishermen caught, based on the counter-rotating screws typical of modern battery-powered HWTs like DM2A4, BlackShark and F21), a Yu-7 LWT successor (Yu-11) - where does the Yu-12 fit in and is there a Yu-9?