X

Imtra Learning Center

Imtra’s Learning Center is a great resource for everything you need to know about your boat’s equipment and systems. Everything from product overviews, product comparisons, buying guides, troubleshooting guides, maintenance tips and more can be found here, and it’s always being updated. Be sure to also check out our video library for product demonstrations, how-tos, webinars and much more!

 

Imtra Learning Center

 Which Bow Thruster Type is Best? Tunnel vs. External vs. Retractable vs. Water Jets

Which Bow Thruster Type is Best? Tunnel vs. External vs. Retractable vs. Water Jets

Author: Conrad Taylor/Friday, August 14, 2020/Categories: Thrusters

Rate this article:
3.8

Tunnel vs. External vs. Retractable vs. Water Jets

Imtra thruster expert Peter Nolet reviews four common types and describes the pros and cons of each style for recreational boats.

Bow and stern thrusters come in many shapes and sizes and are used to help maneuver boats in tight quarters by providing thrust in a sideways direction. Different styles of thruster will work best for different types of boats, depending on the cost, complexity and maintenance you are willing to bear. To help sort out what’s best, let’s review this list of the pros and cons of each.

In full disclosure, at Imtra we sell Side-Power thrusters for the North American market and Sleipner has a broad product line matching three of the four styles described—Tunnel, Retractable, and External. To learn more about thrusters generally, read our article “What are Bow Thrusters and How Do They Work?”

The Pros and Cons of Tunnel Thrusters

Image of a tunnel thruster.

PROS of Tunnel Thrusters

Thrusters in “tunnels” are the most common type of thrusters, mostly because they provide the most efficient way of moving water. For every horsepower delivered by your thruster motor, you receive 132 pounds of thrust, pushing your bow or stern in the direction you want. The tunnel concept has been accepted and integrated into boat designs by boat builders worldwide, and manufacturers offer tunnel thrusters in the largest range of sizes with multiple types of propulsion power: DC electric, AC electric and hydraulic.

Tunnel thrusters are also the most cost-effective type of thruster, and are known for their reliability, in part due to a minimum of moving parts. One other benefit is that the tunnel serves as a tubular stringer in the bow, adding strength to the hull.

CONS of Tunnel Thrusters

The most obvious negative to a tunnel is that you will have a good-sized hole cut through your hull, although well-installed tunnels do not cause issues. Tunnel holes create a small amount of drag but if faired properly, this is of minimal or no concern to most boaters. A more significant con to a tunnel thruster is that it is somewhat more expensive to install. It also adds some weight and takes up some space in the bow of your boat.

Graph showing the pros and cons of a tunnel thruster.

The Pros and Cons of External Thrusters

Image of an external thruster.

PROS of External Thrusters

External thrusters fit when all other styles don’t. For example, boats like sailboats or trawlers often won’t have the space to install a tunnel thruster in the bow or stern. This is when the external thruster becomes the obvious choice.

At the same time, externals still have their own tunnel, so they remain efficient, and the fact that they are water-cooled extends their run time. Installation is also least expensive as the units are bolted on and require few holes in the boat.

CONS of External Thrusters

A clear knock against external thrusters is that they create more drag, but that’s only the case in the bow, not the stern, where they live behind the transom. The product itself is more expensive than internal thrusters, delivers lower initial thrust due to its motor design, and generally requires more maintenance, since all functioning parts are outside the boat. Finally, the range of products is narrower than with tunnels, and if you have a larger boat, you may need to install a pair of thrusters to have the power to get the job done.

Graph showing the pros and cons of an external thruster.

The Pros and Cons of Retractable Thrusters

Image of a retractable thruster.

PROS of Retractable Thrusters

For those with performance boats, sail or power, who are worried about the smallest amounts of drag, a retractable thruster may be the best solution. Retractables have the second greatest range (next to Tunnels) and work with all types of propulsion power—DC, AC and hydraulic. Further, because the gear leg is inside the boat, they need less maintenance and there is less need to replace the anodes.

CONS of Retractable Thrusters

Retractable thrusters are the most complex of thrusters and have a lot of moving parts. As a result, they are the most expensive thruster product and the most expensive to install. They are also tricky to install, making a DIY project next to impossible, and there aren’t many boatyards with experience installing a retractable thruster; whereas tunnel & external thruster installations are far more common.

Graph showing the pros and cons of retractable thrusters

Water Jet Thrusters

A water jet

PROS of Water Jet Thrusters

Water-jet thrusters are an older technology and are the least expensive to buy and the least expensive to install on the hull. They also allow for long run times.

CONS of Water Jet Thrusters

Water jets only deliver 10 pounds of thrust per horsepower, far less than the other types. Installation requires running large water hoses through the boat to the through-hulls, which may not be practical in the case of a refit. Boats with water jets also will need to replace their hoses every 7 to 10 years.

Screen Shot 2020-07-22 at 3.19.29 PM

Final Thoughts: Determining the Best Bow Thruster for You 

Hopefully,this breakdown helped you better understand the different types of bow thrusters on the market and the pros and cons of each. Ultimately, the best bow thruster for you will depend on the type of boat you own and your unique needs. 

Contact our team today to learn more.

 

Related Products:

Print

Number of views (20252)/Comments (0)

Please login or register to post comments.

Related Articles

Benefits of Having an Automatic Main Battery Switch for Your Thruster System

Benefits of Having an Automatic Main Battery Switch for Your Thruster System

Sleipner's automatic main battery disconnect switches offer safety and convenience for the bow and stern thruster systems on your boat.
Monday, December 12, 2022/Author: Conrad Taylor/Number of views (1836)/Comments (0)/ Article rating: No rating
Categories: Thrusters
Tips for Troubleshooting Bow & Stern Thrusters

Tips for Troubleshooting Bow & Stern Thrusters

There are many potential reasons for a bow or stern thruster not functioning properly, and many components of any thruster system that need to be checked to diagnose the specific cause of a failure. Before contacting a service technician to troubleshoot any issues with your bow or stern thruster, check these four common causes of thruster issues.

Monday, October 31, 2022/Author: Conrad Taylor/Number of views (12570)/Comments (0)/ Article rating: 3.2
3 Accessories to Make Boating More Convenient

3 Accessories to Make Boating More Convenient

As boats are built with more and more features and systems every year, boat owners are looking for more convenient ways to operate all the equipment on their boats. If you’re often using your boat single-handed or with a smaller crew, it is especially imp
Wednesday, May 11, 2022/Author: Conrad Taylor/Number of views (3307)/Comments (0)/ Article rating: No rating
3 Contributing Factors to Run Time of Sleipner Thrusters

3 Contributing Factors to Run Time of Sleipner Thrusters

One of the most common questions about DC electric bow & stern thrusters is how long they can run continuously before overheating, and the answer is dependent on several factors. This article details what those factors are as they relate specifically to Sleipner (Side-Power) thrusters.

Wednesday, March 30, 2022/Author: Conrad Taylor/Number of views (3175)/Comments (0)/ Article rating: 4.0
Categories: Thrusters
Side-Power or Sleipner, What is the Difference?

Side-Power or Sleipner, What is the Difference?

Side-Power is going back to their roots and rebranding as Sleipner as they continue to expand their product offering beyond just bow and stern thrusters.
Wednesday, May 19, 2021/Author: Conrad Taylor/Number of views (9500)/Comments (0)/ Article rating: No rating
What’s the Difference in Bow Thruster Brands? Sleipner (Side-Power) vs. Vetus vs. Lewmar

What’s the Difference in Bow Thruster Brands? Sleipner (Side-Power) vs. Vetus vs. Lewmar

Three major brands, Side-Power, Vetus and Lewmar have dominated the bow and stern thruster market for years, but what's are the differences among the brands? This article takes a deep dive into the three brands and where they differ from one another
Wednesday, April 28, 2021/Author: Conrad Taylor/Number of views (7718)/Comments (0)/ Article rating: 5.0
Categories: Thrusters
How Victron Can Help Boats Manage Multi-Voltage Electrical Systems

How Victron Can Help Boats Manage Multi-Voltage Electrical Systems

Using a Victron DC-DC charger to use both 12-Volt and 24-Volt power on your boat.
Wednesday, March 31, 2021/Author: Conrad Taylor/Number of views (8232)/Comments (0)/ Article rating: 4.0
Back Cove's EasyDock Difference with Proportional Thrusters

Back Cove's EasyDock Difference with Proportional Thrusters

Imtra thruster expert Peter Nolet explains how Back Cove Yachts have made the most of proportional-control bow and stern thrusters made by Side-Power.
Tuesday, September 22, 2020/Author: Conrad Taylor/Number of views (2950)/Comments (0)/ Article rating: No rating
Categories: Thrusters
Why Scout Boats Chooses Sleipner Proportional Control Thrusters for LXF Center Consoles

Why Scout Boats Chooses Sleipner Proportional Control Thrusters for LXF Center Consoles

We spoke with Josh Slayton of Scout Boats to discuss why they have equipped their larger LXF models with Side-Power proportional control bow and, more recently, stern thrusters.

Monday, August 17, 2020/Author: Conrad Taylor/Number of views (4471)/Comments (0)/ Article rating: No rating
Categories: Thrusters
Sleipner Commercial Marine Bow & Stern Thrusters: FAQs

Sleipner Commercial Marine Bow & Stern Thrusters: FAQs

Frequently asked questions about Side-Power thrusters for the commercial marine market.
Friday, August 14, 2020/Author: Conrad Taylor/Number of views (2105)/Comments (0)/ Article rating: No rating
RSS