What type of engine is usually mounted at the stern of a vessel?

The choice of outboard engines for mounting at the stern of a vessel is correct because outboard engines are specifically designed to be mounted externally on the transom, which is the back end of the boat. This configuration allows for ease of installation, maintenance, and removal while also providing a good balance of power and efficiency for various types of watercraft. Outboard motors offer the added benefit of being capable of tilting up when not in use, which can help reduce drag and protect the engine in shallow waters.

In contrast, inboard engines are located within the hull, which can impact the layout and space utilization of the vessel. Stern drives combine features of both inboard and outboard engines, but they are typically integrated into the hull and have a different form of propulsion. Pod drives, though gaining popularity in some high-performance and luxury vessels, are not as commonly found in typical recreational boats as outboards. Thus, in this context, outboard engines are the most appropriate and commonly used option mounted at the stern of a vessel.