Which engine type is also called inboard-outboard (I-O) and does not use a rudder?

Which engine type is also called inboard-outboard (I-O) and does not use a rudder?

• A. Outboard Engine
• B. Inboard Engine
• C. Stern Drive Engines
• D. Water Jet Pump Engine

Answer: (C)

Stern drive engines, also called inboard-outboard (I-O), put the engine inside the hull but mount a steerable drive unit on the stern. The drive unit carries the propeller and can swivel left or right to steer, so no separate rudder is needed behind the boat. This combination of internal engine with an external, steerable drive is what defines I/O propulsion. Outboard engines are mounted on the transom and steer via the engine unit itself; inboard engines rely on a separate rudder for steering; and water jet pump systems steer with a nozzle or vanes, not a traditional rudder, and aren’t I-O.

Stern drive engines, also called inboard-outboard (I-O), put the engine inside the hull but mount a steerable drive unit on the stern. The drive unit carries the propeller and can swivel left or right to steer, so no separate rudder is needed behind the boat. This combination of internal engine with an external, steerable drive is what defines I/O propulsion. Outboard engines are mounted on the transom and steer via the engine unit itself; inboard engines rely on a separate rudder for steering; and water jet pump systems steer with a nozzle or vanes, not a traditional rudder, and aren’t I-O.