What is an outboard motor?

When purchasing a boat, people can choose an inboard motor, outboard motor or a sterndrive model — a hybrid system that combines elements of the two. So, why would someone choose an outboard motor over other options? Well, outboard motors are extremely popular due to the fact that they are reliable and easily accessible, according J.D. Power. Additionally, they can be easily removed from the water to prevent marine growth on the motor, plus it’s easy to upgrade to a new motor when the time is right.

Inboard motors are situated inside the hull of the ship. They are commonly found in larger vessels because they’re more powerful and fuel efficient, and they’re quieter than outboard motors, according to J.D. Power. However, inboard motors are generally more expensive, and their bulky size makes them difficult to move or transport. When it comes to hybrid models, J.D. Power notes that they come with many of the same pros and cons as outboard models.

If you’re interested in switching to an outboard motor, you have options, including fuel outboard motors and electric outboard motors

Fuel outboard motors

If you prefer a standard combustion engine, West Marine notes there are two primary choices — two-stroke engines and four-stroke engines. Two-stroke models are typically seen as simple, fast and light, and their quick response time makes them a good option for smaller vessels. However, they’re often louder and less fuel efficient. West Marine notes that four-stroke models have become a more common choice in recent years because they’re quieter, more fuel efficient and produce cleaner emissions. However, West Marine notes that four-stroke models are generally heavier and maintenance on them is often more complex due to their makeup.  

Electric outboard motors

If you have a smaller boat, an electric outboard motor might be a good fit, explains West Marine. Electric outboard motors are lightweight, quiet and low-maintenance — although they can be pricey. Even though you'll need to change the battery every few years, you'll save on fuel costs in the long run. Electric outboard motors usually just need an overnight charge, according to ePropulsion.

Fuel outboard motors are a type of internal combustion engine. When air and fuel are mixed and burned, the heat given off generates high-pressure and high-temperature gas that expands to push a piston to do work, explains ePropulsion. Ultimately, the output is pushed all the way down through the transmission and propeller to drive the boat forward.

Electric motors use a battery as an energy source. The motor uses the charge of the battery, converting electric energy into kinetic energy to drive the boat forward, according to ePropulsion.

Deciding between a four-stroke and a two-stroke boat engine will depend on your priorities and the type of boating you plan to do. Four-stroke engines are typically more fuel-efficient, quieter, and produce fewer emissions, making them a better choice for environmentally conscious boaters or long-distance cruising, says boats.com. However, they tend to be heavier and more expensive.

On the other hand, two-stroke engines are lighter, simpler, and often less expensive, offering higher power output relative to their size, but they consume more fuel, produce more noise, and emit more pollutants. BoatingMag.com explains that today's two-stroke engines have made big strides to preventing fuel loss, compared to their predecessors.

It is important to note that not all states allow two-stroke engines, or the use is heavily regulated depending on the waterway, according to California Boating and Waterways. Always check local regulations before you purchase a new engine.

If you're looking for performance and ease of maintenance on smaller boats or for recreational use, a two-stroke engine might be the better choice, while a four-stroke is better suited for longer-term, more eco-conscious boating.

There are many factors to take into consideration when deciding on how much horsepower you need for your specific boat. Formula Boats points out these common factors:

• The boat manufacturer’s limits
• Boat horsepower-to-weight ratio
• Desired fuel efficiency, which will impact horsepower
• How you'll use the boat
• The number of passengers you typically carry
• The amount of your insurance premium (Usually, the higher the engine horsepower, the higher boat's insurance rates.)

The weight of the boat is very important in this equation – the bigger and heavier the boat, the more horsepower you'll need, according to Better Boat. Formula Boats recommends that you have between 25 and 40 pounds of weight for each unit of horsepower. If you typically have a lot of people and gear on board, this will impact the amount of horsepower that will be best. When you are in doubt about appropriate horsepower, follow the manufacturer's recommendations.

Here are some general horsepower guidelines, based on size and use:

The cost of boat insurance boils down to risk. The faster the boat, the greater the risk. An outboard motor that's faster may affect your rate or eligibility. But the speed of your boat isn't the only thing that goes into your premium. Other factors include your boat type, size and value, as well as where you'll be boating (oceans vs. lakes), how much coverage you purchase, and any discounts you qualify for.

Choosing the right outboard motor ultimately comes down to how you use your boat, where you operate it, and what you value most in terms of performance, efficiency, and maintenance. With options ranging from traditional two-stroke and four-stroke fuel engines to increasingly popular electric models, today’s boaters have more flexibility than ever. Advances in fuel injection technology have made modern gas-powered outboards cleaner, more efficient, and easier to start, while electric outboard motors offer a quiet, low-maintenance alternative for smaller boats and environmentally conscious users.

Boat size, weight, passenger capacity, and manufacturer horsepower limits should all guide your final decision, as selecting the appropriate horsepower ensures safe operation, optimal fuel efficiency, and manageable insurance costs. Whether you prioritize lightweight power, long-distance cruising, or sustainable boating, understanding the differences between outboard motor types will help you choose a setup that makes the most of your time on the water and supports your longer-term boating needs.