What kind of merchant ship should an interwar navy build if it secretly intends to use it as an auxiliary cruiser?
Short answerA fast liner with long range is the best basis because liners could sustain speeds that strained conventional cruisers sent to escort or intercept them.
NotesA useful disguised raider would be a fast liner with long range and machinery able to sustain high speed. Wartime liners routinely forced escorting cruisers to run hard enough to require machinery work afterward because warships normally cruise economically and use maximum power only in bursts. Merchant hulls can become effective raiders through endurance and sustained speed without carrying battleship armament.