What Size Trolling Motor for a Kayak

Kayak fishing is great, with relatively little expense you can get out on the water and into harder to reach fishing holes. The one problem: a kayak requires both of your hands to be free for propulsion, leaving your rod unattended. That’s what makes trolling motors one of the best additions to your fishing kayak setup.

I had a lot of questions when I purchased my first one, but the biggest was probably just what size do I need? Luckily, I’ve done the research so you don’t have to go through the same struggle.

​​​How big of a motor does your kayak need? The short and simple answer is, not a very big one. Your kayak might only weigh a few hundred pounds with you and all your gear in it, which is a whole lot less than any aluminum fishing boat models. Choose a motor with about 30 lb to 50 lb of thrust; there can be some variation depending on boat length and weight, but this range is pretty standard.

Is thrust all that matters? Of course not, but it’s a good starting point when browsing for kayak motors. Anything over 60 lb of thrust will probably be overkill: too heavy and requiring too much electricity. Once you’ve narrowed your choice to those with a reasonable amount of thrust, there are other factors to consider.

Note: Check here my guide on the best trolling motors for a kayak.

Understanding Trolling Motor Thrust

One of the most important things to note about thrust is that it’s not an indication of how fast the motor will go; whether you buy something with twenty-five pounds of thrust or a much larger motor with 50+, your kayak will still putter along at around five miles per hour.

Think of it like the horsepower of a car; they can range from 100 hp on an economy vehicle to over 500 on some of the fastest sports cars and heavy-duty trucks, but all of them have a governor that limits their speed.

There are two reasons that the speed is limited on a trolling motor; the first being that a kayak really doesn’t need to travel more than five miles per hour – that’s a pretty good clip if you were paddling manually. The second is that trolling motors are there to assist your fishing technique, they’re not for propelling you to your favorite fishing hole.

A popular rule of thumb for figuring out how powerful of a motor is necessary is two pounds of thrust for every hundred pounds of mass that needs to be moved. Since most kayaks, even those loaded down with gear, won’t run much over a hundred pounds, you probably won’t need more than ten pounds of thrust with you inside of it.

However, that rule assumes calm waters; if you’re fishing in rougher conditions, particularly out in the ocean, you’ll want something more powerful, which is why there are considerably larger motors available. Additionally, larger motors will accelerate a loaded down boat faster, but that’s not really an issue when we’re talking about such low speeds.

What will probably be more important to you having a good fishing experience with your kayak’s trolling motor is the speed setting. Some will come with five or more forward speeds along with a couple of reverse ones. This lets you tailor your speed to your fishing technique and the type of fish you’re hoping to attract.


What Batteries are Needed for a Kayak Trolling Motor

Let’s start with the voltage requirements of your trolling motor because you won’t be going anywhere if you don’t connect it to a battery of some kind. Trolling motors come in a few different sizes: 12, 24, and 36 volts, which correspond to 1, 2, or 3 bulky, lead-acid batteries (lighter lithium-ion batteries are available, but are very expensive).

While weight is not a huge consideration with large aluminum fishing boats, every pound counts with a kayak. Just as importantly, space is at a premium when you’re crammed into a 12’ by 2’ vessel, so for the purposes of kayak trolling motors, stick to the 12 V variety. You won’t need the extra power that comes with more batteries anyways. However, since you are limiting yourself to a single battery, it’s important to understand that larger motors with more thrust will drain the battery quicker.

As always, be sure to purchase a high-quality deep-cycle marine battery. The kind of battery that starts your car is designed to work hard for a few seconds to turn the engine over, not slowly drain over a day as you ramble about. Thankfully the lower thrust motors used on kayaks don’t draw as much power compared to large fishing boat trolling motors, so you can probably get away with a couple of trips without charging the battery.


Shaft Length of a Kayak Trolling Motor

The shaft connects the trolling motor to your kayak and can be anywhere between 24 and 48 inches. The length that is right for you depends on the length of your boat; if you paddle a nine-foot rig, go with something on the shorter end, but if you’re out on seventeen footer, a longer shaft will probably work better.

In any case, you’ll want your trolling motor to sit about 12 inches below the waterline. Any higher and you risk cavitation, where the motor draws water down from the surface and creates a fish-frightening disturbance in it.

A longer shaft allows you to control a longer boat better by putting the business end of the motor further back from the stern. Having the motor further back allows it to exert a greater rotational force (torque) on the kayak, causing it to turn quicker. Think about turning a bolt with a wrench: the longer the wrench’s handle, the easier it is to twist the bolt. This is very useful with a longer boat, but on a shorter one, it makes the handling too sensitive and difficult to control. 


Related Questions

How and Where Do I Mount a Trolling Motor on my Kayak?

The most effective mounts are bow or stern setups as they allow for finer and more intuitive control compared to motors attached to the side of the kayak. You’ll see a lot of anglers using side mounts though, as there are some rather affordable brackets that can be attached to existing rod holders or wedged inside the rim of the rear porthole and you don’t need to drill any extra holes in the boat.

Do I need a Different Motor for Saltwater Fishing?

Trolling motors designed for use in the ocean do provide better corrosion resistance and are a smart investment if you’ll be doing a lot of saltwater fishing. That’s not to say you can’t use a regular trolling motor out in the ocean, it just won’t last as long if you’re doing frequent trips.

Are There Any Legal Issues with Using a Trolling Motor?

The short answer is that it all depends on your state. While most states do not require you to license, title, or register your unpowered kayak, this can change if you add a trolling motor. Be sure to read up on the laws in your area to see what’s necessary before breaking out the fishing gear.


Related Article: What Size Trolling Motor for a ​Canoe

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