Two main types of engines are used in marine modeling. Outboard engines , found primarily on high-performance racing boats, bolt directly to the rear of the hull. The propeller, rudder and drive system are already integrated into the engine's design. Inboard engines , such as the O.S. .15 CV-M , are mounted within a compartment inside the boat's hull. Running hardware can be a mystery to the novice.
Power produced by the inboard engine is transferred to the propeller by a drive shaft.
Behind the propeller is the rudder, used for steering, and the water pick-up tube. This tube captures water expelled by the propeller and routes it through the engine's water jacket. Like cylinder head fins, a water jacket is a mean of cooling. It surrounds the cylinder head with cool water, which absorbs heat and then is expelled overboard. There, you can quickly find out what additional items are required to run it.