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Trolling Motor Thrust Ratings: How Much Do I Need?

20th Aug 2019 Steven Johnson

Trolling Motor Thrust Ratings: How Much Do I Need?

How Much Thrust Do I Need?

Most boat owners have experience with gas outboards, but not with trolling motors. When given the ratings in pounds of thrust most wonder exactly what they mean, since most full size boat motors are rated by horsepower. That can make buying the perfect trolling motor in one attempt a little difficult for some people, but it doesn't have to be. Electric motor ratings can be roughly converted into horsepower, which helps bridge the gap between gas and electric motors. However, other factors like the kind of water you're going out on plays a role, as does your boat type. The biggest thing to remember when choosing a motor is that you're not really looking for speed, you're looking to apply enough thrust to control your drift so you slowly work your way in a specific direction. If you've got the right trolling motor, it often feels similar to drifting downstream on calm water. If you want to actually build some speed, you generally need to invest in an electric or gas outboard. That is, unless you're in a fairly light or small kayak. A light kayak with a powerful trolling motor can get some respectable speed on still water. However, a lot of people can still paddle faster.

Comparing Thrust and Horsepower

You can't really compare these two units directly with consistency, because one of them is a measurement of force applied and the other is a measurement of power over time. However, you can look at the electricity use on the motor and convert the wattage to horsepower. If you do, you'll usually find trolling motors measure up between a half horsepower and 2hp. As an example, the mid-size 55lb thrust trolling motor has the equivalent power of about 0.84 hp. That means downgrading to a 36lb thrust trolling motor will get closer to half of a horsepower equivalent, and going up to a larger thrust rating like the 86lb motor will take you up to about 1.5hp. For equivalent HP ratings for all of our motors, check out our Trolling Motors: Thrust v.s. Horsepower blog.

So What Rating Does a 16' Boat Need?

Well, it depends on what you want to do and how fast you want to go. On a vessel that large, you're definitely looking at putting an investment into a 55lb thrust motor at minimum. Going up from there is a good idea if you're going to be out on saltwater or you're planning on moving against a current, because the bigger the motor the more it will push. It's also worth looking at a consistent rating. Most motors have a benchmark test showing how fast an unloaded boat of a certain size will go. If you're buying a motor for a kayak or another small vessel, that benchmark could be incredibly helpful in understanding the potential speed you could get. For everyone else, it helps illustrate exactly how much power you get if you were to increase the motor size or thrust rating. Kayak-specific motors around 36 lb thrust can reach speeds around 3 mph, but larger motors can get up to or even over 5 mph. Either way, it's not an incredibly large change if a larger motor is purchase. However, if you don't buy a large enough motor, it might not actually be enough to push your vessel.

Picking the Right Electric Trolling Motor

Since every boat size has a few options, it's worth thinking about things in terms of your purpose. If you need the speed, go bigger. If you need to work against current or to deal with turbulent open water, go bigger. Otherwise, using the smallest size recommended for your boat has some advantages.

  • More natural drift while fishing
  • Less likely to disturb the water enough to startle fish
  • Efficient power use

Trolling motors are designed to work on almost any boat that's an appropriate size, so choosing a good fitment shouldn't be an issue. In fact, these motors are so versatile that many people enjoy moving them between boats. It's a great option if you have a larger bass boat while you cast out or a little kayak you want to be able to outfit with a motor in case you get tired.

Choosing a Salt Water Motor

The chemistry of saltwater is significantly different from fresh water, and that difference can cause scale buildup from minerals as well as corrosion that affects the function of a motor. If you're going out on saltwater, then you will want to look for a motor designed for the job. Some motors that have a higher rating still assume primarily freshwater usage, but saltwater motors are designed with materials that are prepared for the harshness of the saltwater in the ocean and other similar environments. That consideration is an absolute must for both boat owners on the ocean and those near salty inland bodies of water like the Great Salt Lake in Utah. Similarly, if you're looking for a trolling motor, for a light boat like a kayak, then you need to buy one with that small boat in mind. Luckily, kayak-specific designs are popular and easy to compare, and they still come in a few different force capacities.