Outboard motors can be attached to a variety of rigid watercraft in order to turn them into motorboats. They come in a wide range of sizes, with some small enough to be equipped onto a canoe or other slim craft. They also have the benefit of being mechanically simple and easy to repair, meaning that a good one can be obtained second hand. Look on this website for a comprehensive list of used outboards for sale.
These types of motors are ideal for small watercraft because they can be installed and removed with relative ease. Small ones can propel johnboats or bass boats up to a modest size. It takes a larger motor to propel a craft that is heavier or has a broader drag in the water. Gasoline engines do have the potential to overheat if they experience a heavy load for too long, so get one appropriate for the craft.