Choosing the right outboard motor can feel complicated, but it doesn’t have to be. This guide simplifies horsepower, shaft length, and engine types to help you choose the perfect outboard motor for your boat with confidence. We’ll walk you through the essential steps to ensure you get the power and performance you need for a great time on the water.
How to Choose an Outboard Motor: The 5 Key Factors
Making the right choice comes down to five critical factors. Get these right, and you’ll have a motor that perfectly matches your boat and your needs. Before you do anything else, find your boat’s capacity plate—usually located near the helm or on the transom—as it contains the essential specifications you need.
- Factor 1: Horsepower (HP) needed for your activities.
- Factor 2: Shaft length measurement for your transom.
- Factor 3: Steering system (tiller or remote).
- Factor 4: Engine type (2-stroke, 4-stroke, or electric).
- Factor 5: New vs. Used condition and budget.
Step 1: How Much Horsepower (HP) Does Your Boat Need?
The first question is always about power. Your boat’s capacity plate states the maximum legal horsepower rating. You must not exceed this limit. For optimal performance, consider your primary activities. Fishing in calm waters requires less power than pulling a waterskier.
A good rule of thumb is to aim for 70-80% of your boat’s maximum HP rating. This provides a great balance of power, performance, and fuel efficiency. Remember, more horsepower isn’t always better. A motor that’s too powerful adds unnecessary weight to the transom and increases fuel consumption without providing a significant benefit for most boaters.
Step 2: Measuring for the Correct Outboard Shaft Length
Choosing the correct shaft length is critical for performance and safety. An incorrect length means the propeller won’t sit at the right depth in the water, leading to poor performance or even engine damage.
To find the right size, measure your boat’s transom height. This is the distance from the top of the transom, where the motor mounts, down to the bottom of the hull.
- Short Shaft: 15 inches (for transoms around 15-16 inches)
- Long Shaft: 20 inches (for transoms around 20-21 inches)
- Extra Long Shaft: 25 inches (for transoms around 25-26 inches)
Match the motor’s shaft length to your transom measurement to ensure the anti-cavitation plate sits just below the water’s surface when running.
Step 3: Tiller Control vs. Remote Steering
How you steer your boat is a key decision that impacts your experience and your boat’s layout.
- Tiller Control: This is a handle attached directly to the motor for steering and throttle control. It’s a simple, direct system best for smaller boats like jon boats, dinghies, and small fishing boats where the operator sits in the back.
- Remote Steering: This system uses a steering wheel and controls at a console. It’s the standard for larger boats, offering more comfort and a better view from the helm.
Consider your boat’s design and your personal preference. Tiller systems are less expensive and easier to install, while remote steering provides a more car-like driving experience but comes with higher costs and more complex installation.
Step 4: 2-Stroke, 4-Stroke, or Electric? Pros & Cons
The engine technology you choose affects weight, fuel efficiency, noise, and maintenance.
- 4-Stroke: This is the modern standard. 4-stroke outboards are quiet, incredibly fuel-efficient, and produce lower emissions. Their main drawback is that they are typically heavier than their 2-stroke counterparts.
- 2-Stroke (Direct Injection): Modern direct-injection 2-strokes are lighter and provide faster acceleration, making them popular for performance applications. However, they can be louder and less fuel-efficient than 4-strokes.
- Electric: Electric outboards are silent, require minimal maintenance, and are eco-friendly. Their primary limitation is range, which is dictated by battery capacity, making them best for smaller boats on protected waters.
| Engine Type | Pros | Cons |
|---|---|---|
| 4-Stroke | Quiet, Fuel Efficient, Low Emissions | Heavier, More Complex |
| 2-Stroke (DI) | Lightweight, High Power-to-Weight Ratio | Louder, Higher Emissions |
| Electric | Silent, No Emissions, Low Maintenance | Limited Range, Long Recharge Time |
Step 5: New vs. Used Outboard Motors
Your budget will heavily influence whether you buy new or used. Each has distinct advantages.
Buying a new motor provides a full manufacturer’s warranty, the latest technology for fuel efficiency and performance, and ultimate peace of mind. A used motor offers a significantly lower initial cost, which can be a great value if you find a well-maintained engine.
When inspecting a used outboard, always check for signs of corrosion, verify the engine hours, and perform a compression test. A motor with consistent compression across all cylinders is a good sign. Always ask for service records to confirm a history of proper maintenance.
Whether you’re looking for the latest model or a proven used engine, we can help. Browse our selection of new and used motors.
Final Pre-Purchase Checklist
Before you finalize your purchase, run through this quick checklist one last time:
- Does the HP, shaft length, and steering system match your boat’s specifications?
- Is the motor’s total weight within your boat’s maximum weight capacity?
- Have you factored in the costs of rigging, controls, and professional installation?
- Have you reviewed the warranty details for a new motor or the service history for a used one?
Frequently Asked Questions
What are the most reliable outboard motor brands?
Leading brands like Yamaha, Mercury, Suzuki, and Honda have strong reputations for reliability and performance. The best brand often comes down to local dealer support and personal preference.
How many hours is a lot for a used outboard motor?
For a 4-stroke motor, anything under 500 hours is considered low, while over 1500 hours is getting high. However, a motor with high hours and a perfect service history is often a better buy than a low-hour motor that has been neglected.
Can I install an outboard motor myself?
While possible for smaller, tiller-controlled motors, professional installation is highly recommended, especially for remote-steer engines. A professional ensures the motor is mounted securely, and all rigging is done correctly for safe operation.
How do I determine the year of an outboard motor from the serial number?
Most manufacturers have a model code or a specific character in the serial number that indicates the year of manufacture. You can typically find this information on the manufacturer’s website or by contacting a dealer with the serial number.
What is the difference between trim and tilt on an outboard?
Power trim allows you to adjust the motor’s angle while underway to optimize performance and handling. Power tilt allows you to lift the motor completely out of the water when docked or trailering. Most modern outboards combine both functions.
Ready to find the perfect engine for your boat? With the biggest selection of outboard motors in the USA, we have the power you need from the brands you trust. Our expert team is ready to help you match the right motor to your boat and budget.