Redundancy is a judgment about plausible failures rather than an endless chain of duplicate equipment. Older battleships carried substantial torpedo protection, but modern ships may gain little from displacement devoted to a heavyweight torpedo hit that is already likely to be decisive. Arleigh Burke-class destroyers, Type 45 destroyers, and FREMM frigates cannot reproduce a treaty cruiser's protective depth without sacrificing hundreds of tonnes for a scenario they may not survive. A Mark 48 or equivalent heavyweight torpedo detonating beneath the keel shows why broadside bulges may consume displacement without changing the outcome. Designers should direct scarce weight and cost toward measures that prevent the fatal situation or preserve a meaningful fighting capability after damage.
Notable Point · 55:41-58:48
Choosing which backups a warship needs
Every backup consumes weight and space, so a navy has to distinguish useful recovery measures from protection that will not change the outcome of a catastrophic hit.