How Big Of A Trolling Motor Do I Need? 

When it comes to finding the right trolling motors, there are a couple of factors that come into play.

Get one that’s underpowered, and you’ll have a frustrating day on the water. On the flip side, getting one that’s too powerful is also a waste of money.

The right trolling motor helps lock your location with precision when you’re out on the water for recreation or in search of fish.

Understanding how to choose the best trolling motor for your boat size is key.

You want to find the right size trolling motor with the perfect amount of thrust and features for your needs.

To start, you need to consider two things: the size of your boat and how you intend to use your trolling motor. These will help you determine the amount of power (measured in thrust) and speed and what other features to look for.

Let’s begin.

How to Determine the Right Size

The larger the boat, the more juice it needs. So, you must also keep current, wind, and wave action in mind. You want to make sure that the motor is strong enough to handle heavy wind and current.

As mentioned before, the general rule is to have 5 pounds for every 200 pounds. That also comes down to 2 pounds for 100 pounds gross weight when the boat is completely loaded.

Here’s a great chart from MinnKota regarding the thrust size needed based on boat weight and length:

If you are expecting strong currents or winds, the boat must have more power. That means the thrust should be increased by 10 to 20 percent so that the motor can do its job well. Now, you should remember that boats with a shallow draught are not as resistant to water currents as those with a deep draught.

So, you will need a larger trolling motor for the deep draught or larger boats.

Pontoon boats or boats that have more deck height need more thrust because they have more surface that needs to push against strong winds. When you suspect that you need more thrust than the thumb rule, it is best to err on the side of caution.

So, get a trolling motor that has more power because it is better than the alternative, an underpowered motor. 

What the Jargon Means 

To understand the best trolling motor for your boat, you need to understand certain specifications and what you need from each of them. Here’s a look. 

Thrust

We’ve talked about these values a bit, but the thrust is essentially the value that tells you the power of your motor. Many factors come into play when determining how much thrust you’ll need for your boat.

This is determined by the weight of your boat. When calculating this, you need to consider the gear and the number of people on the boat too.

And if you are expecting strong winds or current, you should go for a bit more than what your weight suggests.

Trolling motor thrust is measured in pounds, and that correlates to the power. So, 72 to 75 pounds of thrust measures up to about 1 horsepower of electrical power (motor voltage)

If you have a standard 12-volt motor, it will draw 60 A power, which will consume about 720 watts of power. As the voltage increases, so does the thrust. Trolling motors usually come in versions of 12 V, 12/24 V, 24 V, and 36 V.

The motors, which have over 100 pounds of thrust can power heavy vessels like pontoon boats. In terms of voltage, that looks something like this.

12 volts = 55 pounds

24 volts = 80 pounds 

Volts

The second parameter to understand is the voltage. This is the battery power the trolling motor needs. As you might know by now, every trolling motor battery is at least 12 volts.

• One 12-volt battery brings you at least 55 pounds of thrust.
• Two 12-volt batteries (24 volts) bring you 68 to 80 pounds of thrust.
• Three 12-volt batteries (36 volts) bring you 101 to 112 pounds of thrust.

Shaft Length

It is recommended that shafts also be long if you are expecting rough waters. The length is important because you need the prop to be submerged adequately. The center of the motor should be at least 12 inches in the water. And if the shaft isn’t long enough, that won’t happen.

The standard length is 42 inches. You figure out the best length for your boat by determining the length of the boat. Then you must check the distance between the shaft’s mounting position on your transom or the boat’s deck to the water.

If your trolling motor is a MotorGuide, you need to add 16 inches to that number. And if it’s a Minn Kota, add 20 inches. Then pick the next closest measurement. If you’re going to be in choppy waters, the prop should be about 6 inches below the boat’s surface when it’s pitching and rolling.

You should also ensure that the motor’s position is fine-tuned so that the vertical alignment matches the mounting adjustment.

Power Consumption

You need to figure out how much energy your trolling motor will demand. This will depend on factors like the battery capacity and the size of the boat. You should also think ahead if you might need to recharge your batteries halfway through the trip. To do this, you need to look into the amp draw.

If you have a motor with a 24-volt battery capacity that gives you 54 pounds of thrust, it may draw 28 amps. But a motor with a 12-volt battery capacity with 44 pounds of thrust can pull 36 amps.

The thing to know here is that if the motor is large, it needs more battery capacity. And if you are fishing for a longer period of time on a 16-inch boat or longer, you need a motor with a 24-volt battery capacity.

Some Helpful Comparisons

Now you know the factors that involve in picking a good trolling motor. So, let’s move on to the next step, which is to compare and contrast.

Bow Mounted Motor vs Transom Mount Motors

If you’re on a bass boat and fishing from the foredeck, you should go for a bow mounted trolling motor. Spring-loaded mounts like the ones Minn Kota makes will avoid damage from groundings. That’s because they let the motor swing away. They can also be used as an auxiliary engine on a small boat. Other things to consider if you’re an angler are spot lock trolling motors features that can lock your boat on a specific location on windy days with ease.

Transom motors, on the other hand, have brackets that let you make height and angle adjustments so that the shaft stays submerged at the correct depth.

Fresh vs Saltwater Motors

This is specific to the waters. If you get a saltwater motor, the components will have seals on them, which will protect them from corrosion due to salt residue.

Hand vs Foot Controlled Trolling Motors

If you want a hands-free expedition on a bow-mount motor, you should get the foot-controlled trolling motor. But this is a matter of comfort, and both models have their advantages.

Final Thoughts

All in all, the most generic advice is that bigger is better in most cases when it comes to getting a trolling motor. So, in an ideal situation, the thrust should be 5 lb for every 200 lb of the boat’s gross weight.

But, of course, that is a generalization, and it is important to remember the parameters that determine the size of the trolling motor. And now you know how to do that.