Quotation from: The Gods of Mars

Written by: Edgar Rice Burroughs

In the matter of equipping a fleet to enter Omean the details
were left to Kantos Kan and Xodar. The former agreed to take such
vessels as we required into dock as rapidly as possible, where
Xodar would direct their equipment with water propellers.

For many years the black had been in charge of the refitting of
captured battleships that they might navigate Omean, and so was
familiar with the construction of the propellers, housings, and
the auxiliary gearing required.