Is there a cost-of-raider versus merchant-tonnage-sunk ratio that determines whether commerce raiding is worthwhile?
Short answerNo simple ratio works, because the raider also delays and reroutes trade and ties up warships, crews, fuel, ammunition, and other resources.
NotesA surface raider creates a wide area of effect even without making contact. Merchant sailings may pause, convoys may take longer routes, and insurance or operating costs rise because the threat cannot be localized confidently. Battleships and cruisers consume fuel, ammunition, maintenance capacity, and crews while remaining unavailable for other operations merely because the raider might appear. A cost comparison based only on merchant tonnage sunk therefore misses much of the strategic and logistical burden imposed on the defender.