Visitors to HAIDA often ask about the brass letters, “F”, “I”, “R” and “E” on the loading doors of the QR Mk VIII torpedo tubes. I have heard guides explain, incorrectly, that it was meant to indicate the order in which the tubes should be fired. Since the tubes had to be fired from aft to forward to avoid interference, this would only have worked when the tubes were trained to starboard.
The use of F-I-R-E may have been a bit of whimsy on someone’s part but it ended there. On a ship with two launchers, the after ones were Q-X-Y-Z while quintuple launchers used F-I-R-E-M and P-Q-X-Y-Z.