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Sizing Up A Bow Thruster Posted on August 8th, 2019 | Posted by john

Sizing up a bowthuster

Sizing up a bow thruster.

Bow Thrusters Directs expert John Ainsworth explains the most important considerations when sizing up for a bowthruster.

By definition, any thruster will have some impact on your boats maneuverability, however the key is to ensure that the chosen bow thruster will do the job efficiently and effectively. Firstly let’s understand what a bowthruster is. Simply it’s a propeller placed at the front of the boat, perpendicular to the direction of travel, and controlled from a helm station. The propeller(s) are turned by powerful electric or hydraulic motors. The thruster allows you to move the bow to port or starboard. Its position is crucial for optimum performance: the propeller must be below the waterline but as close as possible to the bow.

Sounds easy, doesn’t it! But sizing up a bowthruster for your boat can be mind boggling and you’ve probably realised by now there’s plenty of choice. Over the years I’ve seen every man and there dog, produce sizing charts, drawings and now days there are even Apps to help. All of these methods are part of the decision making process, but there’s one thing missing and it’s the most important of all, and that’s practical experience and the knowledge gained. That is why is so important before choosing a thruster for your boat to take guidance from knowledgeable dealers and installers.

Thrusters come in many styles and configurations, however they are generally located in a tunnel that’s installed right through the hull. Although sometimes they are mounted externally or installed so they can be retracted when not in use. If your boat is more than 7 metres long, Bow Thrusters Direct recommends investing in a bow thruster, the benefits it will give you will certainly enhance your boating experience.


What bow thruster do I need

Bow thruster installation

Consider the factors!

Before choosing a thruster for your boat, many factors should be considered.

  • What is the windage of your boat? : This refers to every part of the boat (except sails) that is above the waterline. The windage offers passive resistance to the wind and creates turbulence. If you have large windage, choose a thruster for larger boats than yours, and vice-versa.


  • What type of marina are you in? Consider the average strength of the wind, the currents, and access to your berth to evaluate the necessary power.


  • What type of boat do you have? For example, an 11m flat-bottomed model with little draft below the bow reduces the installation options.


  • What is your budget?

There are many thruster manufactures on the market. Sleipner Side-Power are widely accepted to be the best available on the market. There thrusters are the 1st choice of the major boat manufactures. These include Princess Motor Yachts, Sunseeker, Fairline and Oyster to name but a few.


sizing up a bow thruster

Side-Power Thruster Range


At this point you’ve considered and thought more about your boats characteristics than you’ve done for a long time. You know more about your boat now and you’re ready to commit to a thruster. This is where Bow Thrusters Direct come into their own. Confidently, we’ll correctly specify the perfect model thruster for your boat. It’s control and charging system and advise on how to maximise performance by installing the unit correctly.

Thrusters are passion and favourite subject, so let us help you with sizing up a bow thruster.

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