Carrier designers knew that torpedoes posed a serious threat, yet protection competed with other requirements inside treaty displacement limits. Ark Royal, the armoured carriers, and the Yorktown and Essex classes illustrate different choices about underwater defence. The criticism is that governments accepted limits which forced naval professionals to choose between known weaknesses, so inadequate protection cannot automatically be attributed to ignorance of the threat. The numerical argument contrasts capital-ship designs of roughly 40,000 to 45,000 tons with a 35,000-ton limit. For carriers, building each ship to 27,000 tons would use a 135,000-ton national allowance after five ships, placing pressure on navies with commitments across several oceans. The closing comparison distinguishes the potential benefits of arms agreements from the dangers attributed to agreements that leave forces unable to meet foreseeable demands.
Notable Point · 2:10:27-2:15:06
Treaty displacement limits and the known torpedo threat
The treaty argument explains why awareness of torpedo danger did not necessarily translate into adequate protection within fixed displacement and fleet-size limits.