the Third Century BC Ptolemy IV built a twin-hulled version
of the trireme, which was 420 feet long from its 79 foot high
stern to its four massive battering rams, yet drawing only six
feet of water. Twenty men worked the three oars in each of the
50 vertical rows of sweeps on the inside and outside of each
hull. It proved too clumsy for battle, but demonstrated extraordinary
ship building capability and skills.
From The Ancient Mariners Time Life Books