What is a Good Size Motor for a Pontoon Boat? (Explained)


What is a Good Size Motor for a Pontoon Boat

If you’re in the market for or have recently picked up a pontoon boat you’re likely wondering what type of motor you will need to power it. You’ve probably heard that most pontoon boats require a long shaft motor, so is that what you should buy?

Most pontoon boats do require a long shaft motor and the longer your boat is, the larger of a motor you will need. If you have a 16-foot-long pontoon boat you can use a 25-horsepower engine to cruise around, but if your pontoon boat is 22 feet long, you’ll need an engine that has at least 150 horsepower in order to get any decent speed.

Knowing what you’re going to use your pontoon boat for and who will be using it will help you to determine which size of motor you should buy and install.

Good Size Motor for a Pontoon Boat

There’s no one size fits all type of motor for a pontoon boat. The size of the motor you need depends on a variety of factors, mainly the following:

The size of your boat. Pontoon boats can come in all shapes and sizes. Most pontoon boats are 16 to 25 feet long, with an average size of 22 feet. The size of your pontoon boat can help you determine what size of motor you need because the larger the boat, the more horsepower you’ll need to run it.

What the boat is going to be used for. You’ll need a different size motor and more horsepower depending on how you’re going to be using your boat.

For leisure activities such as sunbathing or fishing where speed isn’t an issue a lower horsepower engine is fine — 20-60 depending on the size of your boat. But for watersports such as waterskiing, tubing, and wakeboarding you’ll need an engine with horsepower of between 150-120 that will allow you to reach the speeds (likely 30-50 mphOpens in a new tab.) you need to effectively participate in these activities.

How the boat is designed. The way your boat is designed can affect what size of motor you need. Larger and longer or different-shaped pontoons likely weigh more and will require more horsepower.

How to Measure Your Outboard Motor Shaft Length?

If your engine is already mounted on your boat it’s ready to measure, but if not place it on a stand before you start doing the measurements. Then measure the vertical distance between the inside of the mounting-clamp bracket and the bottom of the cavitation plate. Or if measuring from the other side you can get an accurate measurement by measuring between the top of the boat transom and the bottom of the transom.

Your measurement will likely not exactly fall on one of the below numbers, but whichever number your measurement falls closest to is how you can determine the length of your outboard motor shaft:

  • 15” = Short (S)
  • 20” = Long (L)
  • 25” = Extra Long (XL)
  • 30” = Extra Extra Long (XXL)

Do I Need a Long or a Short Shaft Outboard?

It’s rare to find a pontoon boat that will require an extra long shaft, and even more rare to find one that will require a double extra long shaft, but they do make motors that size for a reason.

Most pontoon boats will require a long shaft, however, it’s important to measure to know for sure before you purchase and install your outboard. The wrong size outboard can cause your boat to not function properly and can even lead to damage.

How Far in the Water Should an Outboard Motor be on a Pontoon Boat?

Mounting the engine in the right spot is essential for the proper use and movement of your pontoon boat. It’s vital to ensure the anti-ventilation plate is below the water so there is no prop ventilation — but you also need to watch that it’s not so deep that the gear case can cause excessive drag.

This measurement needs to be made when the average weight of the cargo the boat will be carrying is in it. This includes people and gear in the position they would be in during your boat voyage. Measuring the boat without its intended weight in it will lead to issues — and possibly damage — running your boat once it’s loaded and in the water.

Does the Placement of an Outboard Motor Matter?

As with any other boat, the placement of an outboard motor on a pontoon boat is crucial to the performance of the boat. Plus, installing it incorrectly can lead to damage to the motor and other parts of the boat.

As mentioned above you must ensure the anti-ventilation plate is below the water so there is no prop ventilation. And be careful that it’s not so deep that the gear case will start to drag as well as create an excessive amount of spray, and reduce the speed and fuel efficiency of your boat.

On the other hand, if your outboard motor is mounted too high this could lead to your motor overheating because not enough water would be running through it to keep it cool. The excess weight of a higher mounted motor could also lead to damage to the transom — which would mean costly repairs.

The anti-ventilation plate is best installed aligned to the bottom of the boat in most cases — especially if you’re a beginner. It comes with adjustments so you can the proper mounting holes and brackets in exactly the right place for your boat.

Mounting a motor lower or higher than recommended can be useful in a few select cases. But before you choose this type of mounting you should let a professional help you weigh the pros and cons of doing it — and be the one to install it.

Is it Easy to Install an Outboard Motor?

Once you’ve figured out the proper size and horsepower for the size, use, and expected weight of your pontoon boat it’s typically pretty easy to install an outboard motor — if you know what you’re doing or have experience installing motors. If the above instructions to measure and install make sense to you then you’re probably able to do it yourself.

Otherwise, it’s best to get a professional to do the install for you — this way you’ll be sure to get the right size motor and a proper install. You may also get a warranty and perhaps some extra service for your pontoon boat.

What Do I Need to Know Before I Buy an Outboard Motor?

When getting your pontoon boat ready with an outboard motor there are a few more things other than how to get the proper measurement and how to do a proper installation that you should know.

Don’t underestimate how much horsepower you will need! Quite a few people will trade up for a new outboard motor after only a year or two because they require more power. You may require more power if you’re using your boat in a river or an ocean as opposed to a lake.

You don’t necessarily need a pontoon motor. Any motor which is suitable for your boat, the weight, and the applications you plan on using it for will work.

Choosing the proper propeller is also important to run your pontoon boat. Since the engine is key for handling a pontoon boat, choosing the correct propeller to work with your outboard motor will give you the most power. Typically, four-blade, big-diameter propellers are best to get the best blade surface possible on your pontoon boat.

Outboard motors can require different types of fuel injection. Typically, outboard motors come with direct fuel injection, electronic fuel injection, and carbureted systems. The main difference between these is how they will operate the boats. There are pros and cons to using each type of system.If you have no experience with these types of injection systems talk to a professional to get the best advice for your particular boat and what you intend to use it for.

What are Pontoon Boats Most Often Used for?

Pontoon boats are a popular type of recreational boat that uses pontoons (airtight, hollow tubes which add buoyancy to a structure) to float. They’ve always been used for things that don’t require a lot of speed like leisurely boat parties, fishing, and sunbathing.

Over the years manufacturers have changed the design and made more modern pontoon boats — and some are now quite luxurious. Even newer pontoon boats are generally still used for the same types of activities as they were originally created for — but some are a bit faster and sleeker as they’re out on the water. They’ve become popular with users who love to do many different types of watersports.

Under ideal conditions, with the right motor and other parts, pontoon boats can reach speeds of 31 miles per hour.

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