Layered protection can include more than armor plate and voids. The Nelson class used water as part of its protection, earlier ships used coal, and designers have also placed machinery within protective schemes. An outer compartment containing a redundant generator presents a substantial metal obstacle before a weapon can reach more vital spaces. This arrangement makes auxiliary equipment serve its normal function while adding defensive depth.
Notable Point · 45:29-46:36
Using water, coal, and machinery as protective depth
Water, coal, and redundant machinery provide examples of useful mass within protective layers, so an incoming weapon faces more than empty compartments.