Chatham trials put Nelson's torpedo defense under full-scale blast

Trials at the Chatham float first used models to assess Nelson and Rodney's underwater-protection arrangement. Designers then detonated a full-scale charge against a representative structure rather than trusting calculations alone. The blast tore a large opening in the outer plating, yet leakage into the hull remained negligible. Investigators concluded that a ship protected this way should retain a reasonable speed even after a very heavy torpedo hit. The G3's seven-foot double bottom could not be carried over, but earlier experiments indicated that Nelson's reduced five-foot depth still protected against explosions under the ship. The trial also showed that some venting plates were ineffective at peak pressure, so the details were revised rather than treating the initial design as finished.