Deciding on the right size trolling motor can be a difficult and sometimes confusing task for beginners and advanced anglers alike. A motor too small will end up burning through battery power without getting you very far, while one that is overpowered may move your boat through the water too fast leading to potential accidents and scaring the fish away.
This article will take a closer look at trolling motors in detail to determine just what size trolling motor you need for your particular boat. We’ll also take a closer look at different battery types and voltages, and how they play an important part in the bigger picture.
Choosing the Right Trolling Motor
Choosing the right trolling motor is an important decision for any angler since the right motor can make a huge difference in the success of any fishing trip. If you’re looking for certain levels of power, speed, and maneuverability necessary to navigate the waters and get the job done, the right trolling motor can make all the difference.
Selecting the right motor can also provide you with the torque needed to get through the most challenging water conditions such as high wind or heavy currents. And of course, the right motor should also be able to handle the weight of the boat itself, while providing sufficient thrust to get where you need to go without struggling or wearing down the battery.
Trolling Motor Size Chart
This trolling motor size chart provides an easy-to-follow guide to help you determine the correct motor size based on the type of boat you will be using, its overall weight, and the water conditions you are likely to encounter on your trip.
| Max Boat weight (pounds) | Max Boat Length (feet) | Minimum size motor (pounds of thrust) | Voltage |
|---|---|---|---|
| <1500 | 14 | 30 | 12 |
| 1500-2000 | 15-18 | 40-45 | 12 |
| 2000-2500 | 12-21 | 50-55 | 12 |
| 2500-3500 | 23 | 70 | 24 |
| 3500-4000 | 25 | 80 | 24 |
| 4000-5000 | 25 | 101-112 | 36 |
Trolling Motor Thrust Guide for Different Boat Types
What Size Trolling Motor Do You Need for a Canoe?
A canoe generally requires a trolling motor that is lightweight and compact and can produce between 40-50 pounds of thrust. This would mean you should look for a 12-volt Lithium-ion battery. This type is often preferred due to its lighter weight and longer-lasting charge. If your canoe is larger than average or made from a heavier material than aluminum or fiberglass, consider looking for around 55 pounds of thrust instead.
What Size Trolling Motor Do You Need for a Kayak?
A kayak generally requires a trolling motor that can provide up to 30 pounds of thrust. A 12-volt battery is perfectly fine for most kayaks and can provide plenty of thrust for still water as well as slightly windy conditions or areas where the current may be a bit stronger than usual. If you plan on taking your kayak into rough water or want a trolling motor that can withstand the stronger current of a river, consider sizing up by a fair bit and look for 40-45 pounds of thrust instead.
What Size Trolling Motor Do You Need for a Bass Boat?
Bass boats up to 16 feet will normally require a thrust rating of up to 50 pounds which is still in the 12-volt battery category. However, if your bass boat is over 16 feet in length, most anglers will go one step up and look for a 24-volt battery that can provide up to 70 pounds of thrust. This extra power helps keep your bass boat on track in windy conditions and choppy water.
What Size Trolling Motor Do You Need for a Jon Boat?
Jon boats can be a similar size when compared to a bass boats but are normally much lighter in weight. This means a jon boat up to 24 feet in length can do just fine with a 12-volt battery that provides 40-55 pounds of thrust. If you plan to have several people on board or will be fishing in an area where the current may push you around, consider going up to a higher thrust and voltage.
What Size Trolling Motor Do You Need for a Pontoon Boat?
Pontoon boats are considerably larger and heavier than other boats on this list. They are also very prone to being pushed around by the wind and current and might not be as streamlined as a bass boat, for example. Most anglers will go with a larger trolling motor that can provide around 80 pounds of thrust or more, which means you are looking at a 24 or 36-volt battery.
Trolling Motor Shaft Length
How Is Trolling Motor Shaft Length Measured?
A trolling motor shaft length is normally measured from the top of the propeller housing to the bottom of the motor itself. Any and all measurements should be done in calm water when the boat is floating freely and not touching a dock or underwater structure.
It’s not uncommon to see a measurement from 30 to 70 inches or sometimes more depending on the brand and size of the trolling motor. If your measurement for a transom mount is more than 22” from the transom to the water line, it’s important that you consult your boat’s user manual or contact the trolling motor factory for recommended shaft length.
In most cases, a bow measurement will be considerably longer than one mounted on the transom. This is due to the bow of the boat “riding the waves” a bit more than the heavier stern would be, which is where the transom installation point is located.
Shaft Length for a Bow Mount Trolling Motor
This table will provide anglers with a quick list of the most commonly recommended shaft length when mounting your trolling motor on the bow of your boat or other watercraft. Keep in mind, bow shaft measurements are commonly longer than transom-mounted lengths simply due to the location of installation.
| Distance From Bow to Waterline | Recommended Shaft Length |
|---|---|
| 0” – 10” | 36” |
| 16” – 22” | 42” – 45” |
| 22” – 28” | 48” – 52” |
| 28” – 44” | 54” – 72” |
| 45” or more | 87” |
Shaft Length for a Transom Mount Trolling Motor
This chart will help you be able to easily pinpoint the recommended shaft length when transom mounting your new trolling motor. Whether you are installing it on a low-slung jon boat, or a higher bass boat, this convenient chart will give you a good starting point at a glance.
| Distance From Transom to Waterline | Recommended Shaft Length |
|---|---|
| 0” – 10” | 30” |
| 10” – 16” | 36” |
| 16” – 20” | 42” |
| Over 22” | Check Motor Installation Guide |
Can a Trolling Motor Shaft Be Too Long?
While a longer shaft can be beneficial in some cases, being too long is a real issue as well. A trolling motor shaft that is quite a bit too long can get caught on the bottom of the lake, tangled in thick vegetation, or end up getting damaged when scraping against rocks or logs the hull of the boat may pass right over.
Additionally, some anglers have reported a higher amount of vibration coming from the trolling motor when the shaft is too long, which can damage the motor itself or cause unbalanced propulsion. Extra vibrations can also damage mounting hardware or loosen bolts over time, potentially leading to your motor falling off the boat entirely.
While this is an extreme case, the longer you use a trolling motor with a shaft that is too long, the more damage can be done over time. It’s important to measure the installation point on the bow or transom when your boat is floating in still water under a normal load in order to get a precise and accurate length.
Trolling Motor Battery Voltages
12V
A 12-volt trolling motor battery is the most common voltage available. This size of the battery is designed to be used intermittently or on lightweight vessels such as canoes and kayaks.
It is typically a lead-acid battery type, which can provide a cost-effective and reliable constant power source while also being very affordable when it comes to the initial purchase. With a 12v battery, you can expect up to five years of use and excellent performance for lightweight boats.
24V
A 24-volt trolling motor battery is great for providing steady or reliable intermittent power. It is normally made up of two 12-volt batteries working together and is most commonly found in the lead-acid type but lithium ion and AGM types are also available.
This battery is very efficient when used over extended periods of time, and requires very little maintenance overall. It’s still on the reasonable end of the initial purchase price scale, making it a great option for anglers on a budget.
36V
Most 36-volt trolling motor batteries are made from high-quality materials and are designed to stand up to the rigors of marine environments. They are specifically made to provide larger amounts of power over a long amount of time.
This size of the battery is great for larger boats, or motors needing a higher power output and better performance. You’ll get efficient operation from this size of battery over long hours, allowing you to stay on the water longer to catch that next trophy fish.
Trolling Motor Battery Types
Flooded Lead-Acid
Flooded Lead-Acid trolling motor batteries are a popular choice for any anglers looking for a reliable and cost-effective battery to install on their boat or other vessels. These batteries are specifically designed to provide a steady and reliable amount of power, making them the perfect choice for most trolling motors and almost all types of marine electronics.
The biggest advantage to having one of these batteries is that they are fairly inexpensive to purchase, are easily maintained, and can provide a reliable source of power on board. The biggest issue, however, is that they can be prone to a buildup of lead sulfate crystals if not properly cared for.
AGM (Absorbed Glass-Mat)
Absorbed Glass-Mat, or AGM, batteries are the most popular type for trolling motors because of their superior performance, extremely high levels of durability, and very long lifespan. AGM batteries are designed to keep their charge longer than other types of batteries making them great for use on long fishing trips.
These batteries are also very resistant to vibration and shock making them suitable for rough rivers and choppy water and are almost entirely maintenance-free as far as having to top off electrolyte levels.
Lithium Iron Phosphate / Lithium Ion / LiFePO4
Lithium Ion batteries are a popular choice for anglers and other boating enthusiasts because of their lightweight and long-lasting power. These batteries are fully capable of providing a high amount of power for a relatively low amount of weight, which makes them great for canoes, kayaks, and other small boats.
The main advantage of lithium-ion batteries is the fact that they can be recharged multiple times, and they offer an extremely long life cycle. You can also get a consistent power output from these rechargeable batteries, allowing for more reliable performance with onboard electronics, underwater cameras, or lighting systems.
