An immunity zone attracts scepticism if a ship rarely fights at the ranges it describes. The criticism here is that American immunity-zone calculations often covered ranges shorter than those at which engagements began. A theoretical protection envelope has limited relevance to an engagement fought outside it. No particular ship, shell, or numerical zone is specified in this comparison.
Notable Point · 4:22:28-4:22:49
Armour immunity zones and the ranges of actual combat
The practical value of an immunity-zone figure depends on whether ships actually fight within it.