What You Need to Know About Bow Thrusters and Power

Bow thrusters are handy propulsion systems that can get boaters out of a tight space, keep the front of a boat straight, and even add value to a vessel. So, exactly what does a bow thruster do, and how do they work? Below, we answer these questions and more as we take a deep dive into everything bow thrusters. Let’s dive in!

What Do Bow Thrusters Do? 

Bow thrusters provide an excellent extra propulsion system for your boat. Essentially, they’re small propellers located below the waterline, near the bow, that can steer the boat sideways. These are most helpful when you’re trying to push the bow of the boat to the right or left.

Because the propellers face sideways, they can propel the boat from side to side without changing orientation. Moreover, if you have both bow and stern thrusters, you’ll be able to move your entire boat in a sideways direction, rather than just the bow. This can be very helpful for docking. 

Which Is Better: A Bow Thruster or Stern Thruster? 

This is a great question, as both bow thrusters and stern thrusters can differ in price and function. In general, bow thrusters tend to be more expensive, especially in terms of installation. However, many avid boaters would consider them essential compared to a stern thruster. 

While stern thrusters can be very convenient when docking or maneuvering a boat, some say they’re not absolutely essential. This is because most anglers have other means of steering the back end of their boats, including rudders and propellers. Thus, while bow thrusters tend to be a bit pricier, owners seem to get the most benefits from a bow thruster. 

What Are the Disadvantages of Using Bow Thrusters? 

Bow thrusters can be useful in certain situations, but they’re definitely not for everyone. For example, the upfront costs can be high. The maintenance and repairs tend to be costly, and the performance of bow thrusters can vary greatly depending on the weather, current, and waves.

Moreover, most bow thrusters need a powerful motor to go with them. Because they don’t use the power from the boat itself, they usually come with an induction motor located just above the thruster, which requires a lot of power.  

Suggested Reading: How Do Boats Have Electricity? Marine Electrical System Basics

What Are the Benefits of Using Bow Thrusters?

Bow thrusters come with many benefits that can outweigh the cons. They allow your boat to stay on course in high winds and strong currents. They also make it easier to dock in tight spaces. Plus, they can be helpful when positioning the boat for fishing. And they’re extremely easy to use. A boat equipped with a bow thruster will be that much more appealing to potential buyers, giving you a good return on your investment. 

How Are Bow Thrusters Powered?

There are two main options for bow thruster motors: electric and hydraulic. By far, the most common choice is electric, simply because it’s so much easier and cheaper to install and much more efficient. A hydraulic system requires the engine to idle up for full power which can hinder other maneuvering functions. Electric units provide much finer control of power flow and do not rely on the engine directly.

So, what provides the power behind the electric motor? Sometimes they operate off AC induction motors, but most are DC powered. These do not require a generator or inverter and are powered by the batteries. You’ll not only need to factor in the weight and space for the bow thruster, but also its motor and batteries. 

How Many Amps Does a Bow Thruster Use?

The answer to this question depends on the size of your motor and the voltage it’s operating at. In general, a 12V bow thruster with a thrust of 132lb will typically draw about 250 amps. Conversely, a bow thruster with 176lb of thrust will need a fuse of at least 355 amps. As the thrust (and horsepower) increases, so do your energy needs. This is why it’s so important to make sure your boat can handle the power requirements of your bow thruster. 

Need a refresher? Learn the differences between Amps, Volts, and Watts in layman’s terms.

What Type of Battery Is Best for a Bow Thruster? 

Weight and space are very limited when you’re on a boat. So, which batteries are best when it comes to density and weightlessness? Let’s take a look.

Hands down, lithium batteries take the cake. On average, they’re up to 50% lighter than lead-acid batteries, and they take up much less space without compromising power. Lithium batteries are also maintenance-free, have a much longer lifespan, and can handle a greater depth of discharge. Most anglers know that it’s a clear choice: lithium is best for boats. 

Not convinced? Find out more reasons Why Boaters Are Choosing Lithium Batteries for Their Marine Batteries.

How Long Can You Run a Bow Thruster?

By design, bow thrusters are only supposed to run for a maximum of three or so minutes at a time. This is because they don’t typically propel the boat over long distances but instead maneuver it into tight spaces or temporarily help it steer against a current. However, most bow thrusters require a lot of power in a short amount of time.

Thus, even though you might be running your boat thruster for just a few minutes, it can potentially draw up to 25 amp-hours at a 500 amp drain. Thus, short bursts of activity with plenty of time to recharge are best. 

How Much Does a Bow Thruster Cost? 

Bow thrusters range in price depending on horsepower, thrust, and quality. In general, you’re looking at a price point between $2,000 and $6,000. Some examples include a Side-Power SE Series bow thruster at $1,969 and a Side-Power EX Series Single External Pod Bow Thruster Pod at $5,699. 

Are Bow Thrusters Worth It?

It depends! Do you frequently find yourself needing more steering power when you’re docking or even out on the open water? Can your boat (and your budget) handle the investment? If so, a bow thruster may be completely worth it. Many avid boaters absolutely love their bow thrusters — just make sure you have the battery bank to power it!