Engineer: Semiplaning monohulls are a new kind of ship that can attain twice the speed of conventional ships  Due to increased fuel needs, transportation will be much more expensive on semiplaning monohulls than on conventional ships  Similarly, travel on jet airplanes was more expensive than travel on other planes at first, but jet airplanes still attracted enough passengers to be profitable, because they offered greater speed and reliability  Semiplaning monohulls offer the same advantages over traditional ships
Thus they will probably be profitable as well
It draws an analogy between semiplaning monohulls and conventional ships that constitutes an objection to the argument's main conclusion, one that is subsequently rejected by appeal to another analogy.