Compare a Sterndrive and an Inboard engine for Power Boats

We are comparing Sterndrive 1/0 vs an inboard engine for Power Boats. Most express cruiser style power boats offer both sterndrive inboard outboard (IO) and inboard (direct drive or V-drive) engine propulsion system options. Choosing between these engine drives, should be given careful thought. It is an expensive investment and it is worth taking your time choosing the best model for you. Speaking to a professional is well worth your time and money to speak to the experts.

The Sterndrive Inboard/Outdrive Motor

A sterndrive, is an inboard/outboard motor that has an outboard lower unit which connects up through the transom of the boat to an inboard diesel or gas engine.

The sterndrive is a widely available and popular for boats under 30 feet. The sterndrive I/O has many advantages compared to a regular inboard boat motors. .

  • Performance: An inboard, outboard motor is well known for its speed. The positioning of the outdrive motor in the back of the boat, is what gives you a better and faster performance. This is the type of boat you would want if you are looking for a fast speedboat. Other inboards are placed more towards the middle part of the boat and would not be as fast.
  • Maintenance: The maintenance of a Sterndriver I/O driver is the biggest disadvantages. It is not so much a problem in freshwater. It is the salt water exposure that makes it prone to corrosion. One of the best ways to minimize major damage, is to use zinc anodes. It will need to be replaced often and the use of an speciaty antifouling outdrive paint for boats.
  • Reliability: The sterndrive inbord/outboard may not last as long as an inboard boat motor. This is due to the potentional corrosion issue. If you are buying a used boat and motor, inspect the motor yourself and ask for previous maintenance records. Be sure that the boat has been taken care of properly and ask for previous.
  • Convenience: The tilt mechanisms on these motors are excellent for shallow water, and as well, are very easy to drive and control in most areas.
  • Efficiency: These sterndrives are now designed with an improved structure which as impovet their speed and gives you excellent fuel economy. .

There are two leading manufacturers of these motors. Volvo and Mercruiser are excellent companies who have set the bar with their manufacturing of their products. The top of the line motors for each, the Mercruiser Bravo 3 outdrive and the Volvo DPR DuoProp sterndrives are popular, long lasting and will hold their value down the road.

Inboard Engines

The Inboard motors use direct drive or V-drive transmissions to power engines. They are popular for the large power boats over 30 feet. This type of drive shaft sits completely submerged in the water and are normally used in larger power boats.

    • Performance: The weight of the I/O are centered deep in the hull of a boat. This improves the stability of the boat and provides a much more of a smooth and stable ride.
    • Maintenance: Inboard engines require much less maintenance than outdrives, especially those in salty water. Boat zinc anodes are required on the drive shafts to help reduce corrosion on shafts and propellers. The engine compartment is quite small and can be a little awkward to get into on some of the small boats.
    • Reliability: Inboard motors are more resistant to corrosion and they tend to last longer than the sterndrive inboard engines. They don’t usually have the same corroson problems as sterndrive vessels.
    • Convenience: The propellers are tucked away under the boat further than a sterndrive. Without a tilt-up mechanism an inboard engine boat would have a disadvantage of an inboard boat motor as compared to an I/O motor.
  • Efficiency: The angle of the propeller shafts with the inboard engines have lower fuel efficiency and less overall performance with the same size motor as inboard outboards.

Choosing a Drive Type for Boat Engine Propulsion

A boat size and the type of water a boat will be used in are two of the biggest determining factors when selecting drive type. Always compare sterndrive I/O motors and the V-drive inboard motors. Look at the advantages and disadvantages. Each engine propulsion system option for a power boat has trade-offs. Your choice on any engine drive should be based on an individual boater preferences and how the boat will be used.