Fire Control: Optical | Yamato | Iowa | Bismarck | Richelieu | King George V | Vittorio Veneto | South Dakota |
---|---|---|---|---|---|---|---|
Main Rangefinder Base Length | 15 meters | 13.5 meters | 10.5 meters | 12 meters | 4.6 meters (6.75m in later ships) |
12 meters | 13.5 meters |
Turret Rangefinder Base Length | 15 meters | 13.5 meters | 10.5 meters | 12 meters | 9.25 meters | 12 meters | 13.5 meters |
Quality of Optics | 10 | 7? | 10 | 7? | 7? | 7? | 7? |
RPC (training,elevation) | No, No | Yes, Yes | No, Yes | Yes, Yes1 | No, No | Yes, Yes2 | Yes, Yes |
Night-Fighting Optics | 10 | 7? | 8 | 7? | 7? | 7? | 7? |
Overall Optics Rating | 10 | 7 | 9 | 7 | 6 | 7 | 7 |
Fire Control: Radar | Yamato | Iowa | Bismarck | Richelieu | King George V | Vittorio Veneto | South Dakota |
Gun-Control Radar | Mk 2, Mod 2 | Mk 13 | FuMO 23 | Type 284M (UK) | Type 274 | E.C.3 ("Gufo") | Mk 13 |
Wavelength | 10cm | 3cm | 82cm | 50cm | 10cm | 75cm | 3cm |
Power Output | 2kW | 50kW | 8kW | 150kW | 400 kW | 1kW | 50kW |
Capability | Limited FC | Blindfire | Limited FC3 | Blindfire | Blindfire | Range Only FC | Blindfire |
Raw Radar FC Rating | 5 | 104 | 5 | 8.5 | 9 | 5 | 104 |
Overall Fire Control Rating5 | 5 | 10 | 5 | 7.5 | 8 | 5 | 10 |
Then there's the fact that all radar fire-control is not created equal. Radar operating at meter or decimeter wavelengths is useful for ranging, but lacks the angular accuracy necessary for training. In practical terms, this means that a decimetric set can develop a range solution via radar, but must rely on an optical director to supply training information for the battery. This hybrid fire-control solution is, of course, limited by the quality of the optics available, and also by the visual horizon (which is closer than the radar horizon), and weather conditions. Only with the advent of 10cm and (later) 3cm wavelength sets was true 'blindfire' radar fire-control achievable, wherein the firing ship need never come into visual range of the opposing vessel. The Germans, Japanese, and Italians never developed sets of this capability (both the Japanese (despite its 10cm wavelength) and German sets were usable for fire control against a battleship-sized target only out to a range of about 27,000 yards.) The bottom line is, then, that the Allied vessels, and particularly Iowa and South Dakota, would enjoy an enormous advantage in gunfire control over their adversaries. She would have the ability to lob shells over the visual horizon, and would also perform better in complete darkness or adverse weather conditions.
The final adjusted rating also reflects the fact that American FC systems employed by far the most advanced stable vertical elements in the world. In practical terms, this meant that American vessels could keep a solution on a target even when performing radical maneuvers. In 1945 test, an American battleship (the North Carolina) was able to maintain a constant solution even when performing back to back high-speed 450-degree turns, followed by back-to-back 100-degree turns.7 This was a much better performance than other contemporary systems, and gave U.S. battleships a major tactical advantage, in that they could both shoot and maneuver, whereas their opponents could only do one or the other.