Béarn lost much of the waterline armor expected in her original battleship design. The conversion instead extended coal bunkers alongside the engine rooms and forward oil tanks. Those spaces supported the torpedo bulkheads and improved resistance to the increasingly powerful underwater weapons designers expected. The arrangement is a useful reminder that an awkward carrier conversion could still preserve a serious battleship-derived approach to underwater protection.
Notable Point · 1:32:20-1:33:10
Béarn retained coal bunkers as underwater protection
The Béarn conversion removed battleship belt armor but extended coal bunkers to support the torpedo bulkheads around machinery and fuel spaces.