Let me try again...... The comment has been made that US fire direction Radar was unreliable and ineffective, and certainly at times it was (often because of poor training). Well, I can give you a couple instances where it was very effective indeed!!! At the battle of Empress Augusta Bay, a force of four American light cruisers and some destroyers opened up on a force of two Japanese heavy cruisers, two light cruisers and the same number of destroyers. It was at night, and the range of first contact was 20,000 yards. There were some squalls, and the Japanese float planes either saw nothing, or misidentified the American ships and their location, direction, etc. USS Montpelier had seen the Japanese force on its radar, and the US force was speeding North to intercept. First the Americans split off its van destroyer screen in one direction, and its afterguard destroyers in another so as to launch torpedoes, while the cruisers kept on, evntually performing a turn so as to present broadsides. It was at this point the Japanese lookouts noticed the American destroyers, and started to maneuver, but it was too late, and they were in too confused a formation for such turns, which produced several collisions between the Japanese ships. Regardless, the US cruisers opened fire on the largest Radar 'blip,' which turned out to be the light cruiser 'Sendai.' Sendai was hit square by the first three American salvos from the four US cruisers (note, no 'ranging shots' used), immediately burst into flames and sank!
Same thing happened in the classic battle between the US Battleship Washington and the Japanese battlecruiser Kirishima; the first three US salvoes were all hits, and turned Kirishima into a pile of burning wreckage (I don't care what it is; if it is hit by nine or ten 16" rounds, it is combat ineffective, if not sinking)! With this kind of accuracy due to Radar-directed gunfire, additional hits are not really required, as the victim could be finished off at leisure with torpedoes, aircraft, etc....
Finally, while I certainly agree that the Yamatos would take an enormous amount of punishment before sinking, I must emphasize again that there is a big difference between a ship actually sinking, and becoming combat ineffective. Combat ineffective means it can't shoot, move, or communicate, and if any or all of those conditions applied, then that ship was doomed if its opponent was still able to conduct these functions. USS South Dakota in the above battle with Kirishima and its accompanying cruisers would most assuredly have been destroyed if not for the presence of USS Washington, as the 'Sodak's' internal power and communications all failed with its first salvo, and for just three minutes afterwards was nothing more than a large target for the Japanese, and received some 40 hits during this time (the damage was so bad that 'Sodak' had to return to the States for repairs lasting almost a year)!
The same would apply if Yamato was quickly struck by a few Radar-directed salvos from USS Iowa, while Yamato was still trying to find the range using 'ranging shots' (as it did while firing at the US Jeep carriers at Leyte Gulf). Yamato might still be afloat, but she would be on fire, directors wrecked, internal communications severed, and possibly her bridge destroyed, and/or even a turret or two knocked out or worse. At that point, how could Yamato respond effectively? And as the range closed further, the US guns would just get more accurate, with a higher volume of directed fire, and more and more damage inflicted with less and less chance for Yamato to strike back. I think under those conditions, USS Iowa would surely prevail, especially as how with her edge in speed, Yamato couldn't even try to escape.....