system
Given the following post, respond as if you're commenting on Reddit:
human
Why are airplane propellers generally in the front and boat propellers in the back?
gpt
Most small boats are designed to glide over and even out if the water at high speed in a process called "planing," which can't happen if the propeller is in front. Airplanes can be designed with "tractor" or "pusher" configurations of propellers. Pusher propeller designs have many disadvantages,  like having to use an airflow disturbed by the fuselage, having to avoid hitting the ground when the pitching up during takeoff, center of gravity issues, vibration, ingesting ice from wings, heat dissipation...there's a long list of problems that are solved by using the tractor design.