Saleen was determined to keep those pirates, and Lex would certainly not oppose to it. Saleen had a good idea, but there were some technical problems. The shape of the ship’s bottom had been designed specifically against waves, and if the alchemical boat were to be dragged rigidly under it, it would not only slow the ship down, but also affect the ship’s balance.
Lex did not put forth a more appropriate idea. She merely rejected Saleen’s design and added a sturdy hook to the tail of the pirate ship, using chains to drag the secret alchemical boat made from the pan’s turtle.
Even so, dragging an alchemical boat behind them would still affect the speed of the pirate ship and would endanger them when there were storms.