The shallow-water torpedo planning gap

An aerial torpedo entering nose-first could dive into the harbor floor before stabilizing. Balancing the weapon and adding extended fins helped its entry, but shallow water left little room for a deep initial dive. The Royal Navy's tension-wire arrangement is explained as pulling the nose enough to produce a flatter entry, with release height still affecting the result. The criticism of Japanese preparation is that their torpedoes remained oriented toward open-ocean attacks despite the importance assigned to Pearl Harbor. Intensive route planning is contrasted with this limited specialization of the weapons. That contrast supports the proposed interpretation that the harbor attack developed from a contingency raid into a principal operation relatively late.