It's simple, just open up the data/menu/menu.txt file, and replace the similarly numbered block of data with the following:
5370=MARK 10|Speed: 36 kt|Range: 3,200 m|Propulsion: Steam
5371=MARK 14|Speed: 46/31 kt|Range: 4,100/8,200 m|Propulsion: Steam
5372=MARK 16|Speed: 46 kt|Range: 12,500 m|Propulsion: Hydrogen Peroxide
5373=MARK 18|Speed: 29 kt|Range: 3,600 m|Propulsion: Electric
5374=MARK 23|Speed: 46 kt|Range: 4,100 m|Propulsion: Steam
5375=MARK 27|Speed: 12 kt|Range: 4,500 m|Propulsion: Electric|Note: Homing torpedo
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