How to Size a Trolling Motor?

How to Size a Trolling Motor?When it comes to selecting the right trolling motor for your boat, one of the most important considerations is sizing. Ensuring that you choose the correct trolling motor size is crucial for optimal performance on the water. In this guide, we will explore the factors you need to consider when sizing a trolling motor, including thrust requirements, shaft length, and boat type. By understanding these key elements, you can make an informed decision and enjoy a smooth and efficient boating experience.

Before diving into the details, let’s take a closer look at the importance of choosing the right trolling motor:

  • Choosing the correct trolling motor size ensures that you have enough power to maneuver your boat effectively, even in challenging fishing conditions.
  • Properly sizing your trolling motor can help prolong its lifespan and prevent performance issues caused by overloading.
  • Having the right amount of thrust is essential for enjoying additional features like GPS functionality or spot-lock capabilities.

Now, let’s dive into the specific factors you need to consider when sizing a trolling motor:

Calculating the Required Thrust

When choosing a trolling motor for your boat, it’s essential to determine the required thrust to ensure optimal performance on the water. Calculating the required thrust is a straightforward process that involves considering the weight of your boat along with other factors such as gear, fuel, and passengers.

To calculate the minimum recommended thrust for your boat, divide the total weight by 100 and then multiply the result by 2. For example, if your boat weighs 3000 lbs, the calculation would be (3000/100) * 2 = 60 lbs of thrust. This calculation provides a baseline for the minimum thrust requirement.

However, it’s important to note that this calculation is a starting point. Additional factors, such as hull design, fishing conditions, and the desired length of use per outing, should also be considered to ensure you have sufficient power for your specific needs. It’s always better to have slightly more thrust than necessary to avoid performance issues on the water.

Factors to Consider:

  • Hull Design: Different hull designs create varying water resistance, which can affect the thrust required. Boats with flat-bottomed hulls typically require less thrust than boats with deep-V hulls.
  • Fishing Conditions: If you frequently fish in areas with fast-moving water or strong winds, you may need additional thrust to maintain control and maneuverability.
  • Length of Use: If you plan on extended hours of trolling or fishing, choosing a trolling motor with higher thrust can help conserve battery power and extend your time on the water.

By taking these factors into account and selecting a trolling motor with the appropriate thrust level, you can ensure a smooth and enjoyable boating experience.

Boat Weight (lbs) Minimum Recommended Thrust (lbs)
1000 20
2000 40
3000 60
4000 80
5000 100

Note: The table above provides a general guide for selecting the minimum recommended thrust based on boat weight. Remember to consider other factors mentioned earlier to determine the most suitable thrust requirement for your specific boating needs.

Selecting the Shaft Length

The shaft length of a trolling motor plays a crucial role in maintaining optimal performance on the water. By choosing the right shaft length, you can ensure that the propeller is submerged at the correct depth to provide efficient power and maneuverability. To determine the appropriate shaft length for your trolling motor, follow these steps:

Measuring the Shaft Length

To measure the shaft length, start from the bottom of the motor head and measure to the top of the motor housing. This measurement will give you the total length of the shaft. Most trolling motors come with adjustable shafts, allowing you to accommodate different water depths. It’s important to note that the general rule of thumb is to have the propeller submerged at least 6 inches below the water surface, ensuring it doesn’t breach the surface or hit the bottom.

Factors to Consider

When selecting the shaft length, consider factors such as the size of your boat, the hull design, and the fishing conditions you’ll encounter. Larger boats with deeper drafts will require longer shafts to reach the desired propeller depth. Additionally, boats with higher freeboards (the distance from the waterline to the top edge of the boat) may also require longer shafts to maintain proper submersion. It’s essential to consult the manufacturer’s guidelines and take into account the specific characteristics of your boat to select the right shaft length.

Manufacturer Recommendations

Trolling motor manufacturers often provide guidelines and recommendations for selecting the appropriate shaft length based on boat size and other factors. These recommendations take into consideration the specific motor models and their performance characteristics. By following the manufacturer’s recommendations, you can ensure that you choose a shaft length that aligns with the motor’s capabilities and your boat’s requirements. Keep in mind that the manufacturer’s guidelines should be used as a starting point, and adjustments may be necessary based on your unique boating needs.

By carefully measuring the shaft length, considering boat size and fishing conditions, and following manufacturer recommendations, you can select the right shaft length for your trolling motor. This will help optimize performance and ensure a smooth and enjoyable experience on the water.

Trolling Motor for Different Boat Types

When it comes to selecting the ideal trolling motor, considering your boat type and its specific application is crucial. Different boats have varying requirements and usage scenarios, and choosing the right motor will ensure optimum performance on the water.

Bass Boats

Bass boats, known for their agility and maneuverability, often require larger trolling motors with higher thrust capabilities. Motors with 70 to 100 pounds of thrust are commonly used in bass boats as they provide precise positioning and extended runtimes. These motors are designed to handle the demands of bass fishing, allowing anglers to navigate through tight spots and change fishing locations quickly.

Jon Boats and Kayaks

On the other end of the spectrum, jon boats and kayaks are lighter in weight and have limited space for wiring. These smaller vessels typically require simpler and smaller trolling motors. The motor size can range from 30 to 55 pounds of thrust, providing sufficient power for trolling and basic maneuvering.

Pontoon Boats

Pontoon boats, with their higher platforms and larger size, benefit from specific trolling motor models designed to accommodate their unique characteristics. These motors often have features like elevated transom brackets, allowing them to be mounted higher on the boat. The thrust requirements for pontoon boats can vary, but it’s common to see motors with 55 to 80 pounds of thrust being used for effective propulsion.

By understanding the specific needs and characteristics of your boat type, you can select the most suitable trolling motor. Consider factors such as maneuverability, weight, and space limitations when making your decision. With the right trolling motor, you can enhance your boating experience and enjoy smooth navigation on the water.


In conclusion, selecting the right trolling motor size is essential for a successful boating experience. By considering factors such as thrust requirements, shaft length, boat type, and intended application, you can make an informed decision. Calculating the minimum recommended thrust based on your boat’s weight and understanding the relationship between voltage and thrust will help you determine the power you need.

Additionally, measuring the appropriate shaft length and considering the depth of the water you’ll be fishing in will ensure optimal performance. It’s important to choose a trolling motor that is suitable for your specific boat type, taking into account its unique characteristics and needs.

Remember, it’s always better to have slightly more power than needed to avoid any performance issues on the water. By following these guidelines and considering the manufacturer’s recommendations, you can select a trolling motor that provides the best performance, reliability, and enjoyment during your boating adventures.

Richard Dodds

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