New and Used Boat Buying Guide | Outboard VS. I/O?

Posted By Timmy McNamee On April 09, 2015


In boat sales, we deal with a common scenario often. New and used boat buyers come in asking the difference and the benefits between an Outboard and an I/O (sterndrive) engine. When boat buying, they aren't clear on how each can be of benefit to them and their boating purposes and needs. If you are in the market for a new boat (maybe your first boat), you can get stuck on this crucial decsion. We've taken the top 5 benefits of each engine and listed them below to make the comparing less work.

Let’s start with an outboard engine. First, what is it, and what are it’s characteristics? Of course there is the physical difference - an outboard is an entire engine and drive system visibly mounted on the back of the boat. It can be large or small, and a Four Stroke or Two Stroke engine. They are found most often on pontoon boats, aluminum fishing boats, and the occasional fibreglass bowrider (pictured on the right above).

The top benefits to an outboard engine are:

  1. External engine bolted to the transom. This makes the engine easier to replace, remove, or upgrade, and is less expensive to do so vs. an I/O engine. It also takes up less space "in" the boat which allows for a larger cockpit/seating area typically.
  2. The entire engine, prop, and drive can be lifted entirely out of the water. This is a common choice of engine for those who have low water issues, or are looking to take their boats into shallow water. Salt water boaters can reduce corrosion to their engines this way also.
  3. Earlier & Extended seasons are possible. This is a great benefit to those who may live or cottage on an island or water access only propety. Fisherman looking to get out on the water earlier and later in the season enjoy it also.  Based on ithe outboard's design, the block (cooling water) is self-draining. There is far less freeze damage risk putting it in early/late, and leaving it in colder water temperatures.
  4. Lower annual maintenance costs, and easier for the “DIY-er”. Outboards do not need draining (coolant water) for winterizing, it is much easier and less risky to do your own work and maintenance on them. Also, there are no bellows, internal shift cables, gimbal bearings, or alignment to inspect.
  5. Lighter over-all package. The same horsepower can be produced by an engine with less wieght that sterndives, boats with outboards are generally lighter, which makes manuvering and trailering less effort. 
An inboard/outboard (I/O - sterndrive) engine is enclosed within the hull of the boat, usually connected to a external drive unit through the transom (pictured on the left above).
The top benefits to an inboard/outboard engine are: 
  1. Longer Life. Based on it’s robust and heavy duty engineering, it traditinally has a longer life expectancy than an outboard engine.
  2. Heavier can mean more stable. There is typically more weight to a sterndrive engine and this can make it easer to maneuver around the docks (less effected by the wind and currents) and handle more rough water conditions.
  3. Sunpad is common. Enjoy stretching out on a "bed" at the back? The engine is located in the hull of the boat and has a compartment over top which is generally used as a sun pad. This makes is great for lounging on the water with your family and friends.
  4. A full width Swim Platform is possible. The engine being mounted lower and "in" the boat allows the manufacturer the possibility of a large platform for anyone who loves to jump off into the water and get back on the boat with ease. The platform is also highly beneficial for watersports. It makes putting on your board, skis, or jumping onto a tube much easier! This is also a safer area for getting on and off the boat.
  5. A more "car like" feel. The I/O is often quieter, and feels more like the experience you have while driving your car. With the engine tucked away out of sight, there is a more sophisticated feeling while on board and using the boat. 
As this is a common question of new boat buyers, other people have wirtten on this topic - here is an article from "The Lake Boss". When you consider buying used boats, your best ally can be a boating expert in a Certified Marina or Dealership to ask the right questions to uncover your wants and needs. Even better is a marine dealership with a documented program in place to protect you should a mistake be made.

Lower your boat buying risk