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The Right Shaft Length for your Outboard Motor

The shaft length for your outboard is determined according to the type of boat, engine size and propeller. When selecting a shaft length, the height of the vessel's side and transom will determine whether you need a short shaft or long shaft motor. In this guide, we explain which measurements are relevant for determining the correct shaft length. Learn more about which long-shaft or short-shaft outboard is suitable for your boat and make the best and most efficient use of your engine's power. Making sure you have the right shaft length for your vessel will also minimise maintenance to your motor and prevent unnecessary damage. We also explain which is the right shaft length for your inflatable.

Do I Need a Long Shaft or Short Shaft?

Outboard shaft lengths generally come in either long shaft or short shaft versions. Whether you need a long or short shaft outboard does not depend on the length of the boat, as many think, but on the height of the transom. In the following, we explain the difference between short shaft and long shaft outboards and provide an answer to the question "How do I determine the right shaft length for my outboard?"

• An outboard long shaft is suitable for boats with a high transom, usually over 15 inches (approx. 38 cm). A motor with a long shaft provides improved performance and higher efficiency for larger boats.

• A short-shaft outboard, on the other hand, is used for boats with a low transom. This is usually less than 15 inches (approx. 38 cm). A short shaft has the advantage of being much lighter and is therefore excellent for smaller boats and dinghies.

In addition, there are also extra-long shaft and extra-extra-long shaft outboards for sailboats and yachts. On these engines, the outboard shaft length is significantly longer.

When choosing a suitable outboard for your boat, there are some important factors to consider to ensure you get the best possible performance and efficiency.

  • Start by carefully checking the manufacturer's instructions and recommendations. This is essential, as different boat types and models may have specific requirements regarding short shafts or long shafts.
  • Next, measure the exact height of your boat's transom to know precisely which shaft length you need.
  • You should also consider the water depth in which you'll mainly be sailing, as well as if there could be any obstacles in the water.
  • Also think about your own personal preferences and how you intend to use your boat. Selecting a long shaft or short shaft can also depend on whether you tend to sail over longer distances or go on short fishing trips.
  • All the info at a glance here:

    Shaft Suitability Length
    Short shaft (normal length shaft) For boats with a low transom 38 cm approx. (15 inch)
    Long shaft For boats with a high transom 50-51 cm approx. (20 inch)
    Extra-long shaft Commonly used only on sailboats or yachts 63-64 cm approx. (25 inch)
    Extra-extra-long shaft Commonly used only on sailboats or yachts 76 cm approx. (30 inch)
    What is the Right Height for my Outboard?

    What is the Right Height for my Outboard?

    Selecting the correct height for your outboard is essential to achieve optimum performance on the water. Which one is right depends on boat type, engine size and propeller. Before you decide, you must measure your outboard shaft length.

    The correct outboard shaft length is important because of prop placement. The propeller must sit deep enough in the water to produce sufficient thrust. Too high and you'll get turbulent water from the bottom of the boat, too low and you'll have excess drag. For correct installation, we recommend that you check the manufacturer's specifications and find out the optimum setting by carrying out your own tests. If you're still unsure, you should ask a professional for advice before you start your first adventure at sea.

    The graphic shows the area to be measured and the relevant points to start at for long shaft short shaft measurement. The motor mounting surface and the lower edge of the keel are necessary to determine the correct height for your outboard.

    What Shaft Length do I Need for an Inflatable Boat?

    Whether you need a long or short shaft depends on the type of inflatable boat, i.e., kayak, rowing boat, lifeboat or other type.

  • The weight to be carried and the number of passengers must be taken into account.
  • It is advisable to look at the manufacturer's specifications or recommendations to determine the appropriate shaft length and align the boat for optimum performance.
  • Keep in mind the intended use and the conditions of the water you want to be on.
  • Both comfort and safety should be the focus when deciding long shaft or short shaft for an inflatable boat.
  • Also, expert advice can be helpful if you are not sure. Our staff will be happy to assist you and answer any questions you may have.
  • We also recommend you take your motor on a test drive before venturing further afield. Just try different short shaft or long shaft inflatable boat shaft lengths and trust your own judgement to find the model that suits you best.
  • Notes: versions are also available where the shaft length can be adjusted for more flexibility.

    Shaft Length

    TIP

    Take a big step towards more sustainable yachting and add an eco-friendly electric outboarder to your small boat. With an electric outboard you can sail almost noiselessly and emission-free, even in nature reserves. In our SVB guide Electric & Petrol Outboards Tested and Compared you can find out in detail about the advantages and disadvantages of the different types of motor.

    How Deep Should an Outboard Motor Be in the Water?

    To guarantee optimal performance and maneuverability on the water, it is essential to determine the correct depth of your outboard motor, in the water. This applies whether you have an electric outboard, or a conventional combustion engine with a long or short shaft. Answering the question "How deep should an (electric) outboard motor be in the water?" correctly is important, because not only does the proper level ensure reliable operation of your motor, it also means your vessel will drive more efficiently and be safer.

    For electric outboards, determining the correct depth is crucial, as they often generate less lift than conventional petrol engines. The recommended depth may vary depending on the motor manufacturer. However, electric outboards often come with an adjustable shaft length, so your outboard can be set so that it is submerged deep enough in the water to provide sufficient propulsion, but not so deep that the propeller or motor are damaged.

    With a conventional outboard, the optimum immersion depth depends on various factors, including the design of your boat and your motor, as well as their sizes, and the conditions on the water. Generally speaking, however, your outboard motor should be deep enough so that the propeller is fully submerged. This ensures efficient performance and prevents the motor from overheating. However, make sure it doesn't sit too low, as this can impair maneuverability and cause damage.

    You might also be interested in: The best outboard for your boat

    Whether you need a light outboard for your dinghy or a powerful engine for your sail boat - you'll find it here. In our SVB online shop you will find motors from the most popular brands such as HONDA, MERCURY and SUZUKI, ruggedness and top performance guaranteed.

    Environmentally friendly and quiet: Our Electric Outboards deliver on zero emission propulsion. Perfectly suited for small to medium-sized boats, they are a sustainable alternative to conventional engines.

    Check out our Electric & Petrol Outboard Test and Comparison, where we look at and compare the advantages of the different types of motor for you. Find your favourite and get your boat moving the way you want it with the perfect outboard!