Radar Directed Ship to Ship Gunfire

They clearly didn't all the time. At least one US DD was hit by friendly fire in that battle. Timing the fall of shot might give a clue and the size of the return might allow distinguishing between 8" and BB caliber splashes. Note the liberal use of "might".

 

The whole idea does not sound terribly feasible to me; either the dye would have had to be incorporated into the shell at the factory level - a logistical nightmare I would think; or for the big guns, a bag of dye would have had to be loaded after the shell and before the powder - which would make some very pretty muzzle blasts!!
However, since I know squat about Naval Gunnery, I will ask my local expert next week and see what he says.

 

Both the US Mk 3 and Mk 8 FC radars have sufficent resolution in "Precision Sweep - Normal" mode to actually detect individual shell splashes. For an individual ship they can generally pick theirs out simply be observing which splashes appear parallel (or nearly so) to the display on the radar system. Splashes from other firing ships will follow a line that is at some angle to the display. The size of the echo gives a clue to the size of the round too.
The splashes themselves are distinguishable by their not being as bright a return as the target itself. A decent operator can distinguish as small a variance in splash position in the above mode of operation on a Mk 8 of +/- 2 or 3 mil in bearing and +/- 30 yards in range. A good operator could reduce this to +/- 1 mil (or about .005 degrees) in bearing and +/- 15 yards in range.

 

Wow - had no idea the radar was that good

 

Unfortunately, I currently have no way to put up pictures out of Navpers 16116-B Naval Ordnance and Gunnery to show just how simple the radar picutes really are. The system is described in that manual in excrutiating detail.
I looked quickly to see if this book was posted on some site on the internet but apparently it isn't. Although, several book sites listed it as worth between $250 and $400. Apparent score for me!

 

Gene Slover may have the NavPers volumes on his site:
GS-USN-PAGE
I don't recall instances of ship's confusing each other's radar-directed salvoes, but it was common to lose the target within the salvoes. That's where we get all those action reports about targets disappearing from the radar and presumably sinking.
I believe all the navies that used dyes had the packet inserted under the ballistic cap. The Japanese, Americans, British, and French all used dyes. The French included a small explosive to aid in night spotting.

 

"They're shooting at us in Technicolor!"

 

Here is an online picture of what the US late war fire control radar on larger (cruiser / battleship) ships would look like to the operator.

CHAPTER-20-G

Scroll down about two or three pages to see the displays. While those shown are for the later Mk 8 mod 3 and Mk 13 they are identical to the wartime Mk 8 system as far as the displays go.