What Size Motor For A 20ft Pontoon Boat?

What Size Motor For A 20ft Pontoon Boat? | Life of Sailing

Last Updated by

Jacob Collier

January 9, 2023

Key Takeaways

  • A 20 ft pontoon will need to have a 90 - 115 HP motor at a minimum
  • The heavier the pontoon, the slower a boat will usually go.
  • The engine size needed will depend on the purpose of the boat’s usage.
  • Lifting strakes can help increase the speed of a pontoon by lifting the boat over the surface.

You just purchased a preowned pontoon boat, but it doesn’t have an engine. What size of the motor is best for a 20 ft pontoon boat?

The motor for a 20 ft pontoon boat needs to be 90 - 115 HP at a minimum, producing maximum speeds of 25 - 28 mph. The size of the boat, weight, the number of tubes, and the general purpose of the boat are the primary factors in choosing an engine.

Whether cruising around the lake, fishing with the kids, or tubing with friends, the motor of a pontoon boat can make a big difference. Even though pontoons have never been known for the speed of other boats, an engine with more horsepower can open up the possibilities for all kinds of recreational activities. While you want something powerful enough to move you across the water, you don’t want to endanger yourself or your family. Knowing the best size for your particular situation is essential, and there are some critical considerations for choosing the right size engine.


Table of contents

What is the Best Size of Motor for a 20 ft Pontoon?

Pontoon boats come in many sizes in length, design, and engines. From smaller fishing pontoons like the Pond King Pro, barely over 12 ft, to the large 30 ft Bennington Q30 luxury pontoon, prospective buyers have plenty of options.

Engines range in size from 45 HP to 500 HP, depending on the size of the boat. A 20-foot pontoon boat needs about a 90 HP motor (at a minimum) to traverse the water at a speed of 25 - 28 mph. If you prefer to increase the speed of the boat, many manufacturers offer 150 - 200 HP engines that can achieve top speeds of up to 46 mph.

What Should I Consider in Choosing an Engine for a Pontoon?

Many boat owners believe that the size of the engine is the primary thing that determines a boat’s velocity. While it is a significant part of determining speed, there are other essential considerations for determining what is best for your situation.

How Do You Plan On Using the Boat?

The primary purpose of your boat will be essential in choosing the size of motor you need. If you plan on going tubing every weekend (or water-skiing), you will want to choose a boat with a larger capacity. You need a slower boat if you are more interested in cruising around the lake or taking the grandkids fishing.

Stop to reflect on the kind of boating you envision your family doing on the weekends. It is good to discuss this with your manufacturer and get their recommendations concerning what size boat and motor might be best.

What is the Size of the Boat?

Some engines won’t cut it when moving a pontoon through the water. It makes no sense to purchase a large deck area and equip the pontoon with a tiny motor. Your dealer and manufacturer can recommend engines capable of pushing the boat through the water.

Some manufacturers offer double-decker pontoon boats with slip-n-slides of the upper sun deck that empty into the water below. These boats are top-heavy and offer significant wind resistance, so they need larger engines to move them across the water.

How Much Weight Will I Carry?

If you plan to transport many passengers and equipment, you want to choose a boat motor with more horsepower. Heavy boats tend to move more slowly in the water.

The Number of Tubes

Tritoons need larger outboard engines than the dual-tubed pontoon cousins. The minimum engine for a tri-toon is 150 HP, assuming that the boat's length is at least 20 ft. Potential owners should remember that tri-toons are often more expensive because of the extra tube and larger engines.

What is the Size of Water My Boat Will be On?

If you plan on boating on a large body of water (reservoir or open sea), go with a larger motor. Opt for the smaller outboard if you are planning to traverse shallows and riverbeds where steering will be crucial.

How Much Do Pontoon Engines Cost?

Depending on the engine's size, you should spend between $6000 to $20,000 for the motor. Many manufacturers will allow performance options for engines that can be selected by customers who wish to build their boats. These are good sources of information for shoppers.

If you are buying a preowned pontoon, make sure that you inspect a maintenance record for the potential boat that you want to purchase. While there is no “official” carfax for boats, most buyers research the history of their boats on the website of boathistoryreport.com. Ask the seller to produce maintenance records demonstrating that the boat has had fluids changed regularly.

Are There Ways to Make a Pontoon Go Faster Without Upgrading an Engine?

If you do not have the money to upgrade your engine, there are some things that you can do to help increase the speed of your boat. While none of these are as dramatic as increasing your engine's horsepower, they can still shave off seconds.

Install Lift Strakers

Lifting Strakes are thin strips of sheet metal attached beneath the deck between the pontoons and are designed to lift the boat off the water’s surface. Lifting strakes will cost about $5000 to install and should be done by a certified technician. Some manufacturers have options for the installation of these performance options, so be sure to check with your boat maker to see what they would recommend.

Whoever adds the strakes, it is vital for the technician to be careful welding them to the boat without burning holes in the thin aluminum tubes. A leaking tube will negate the effect of the lifting strake by taking on water and making the boat more unstable.

Keep Your Pontoon Clean

Many good pontoon owners give their boats a quick wash and rinse after every use (assuming that they pull the boat out of the water and onto a trailer each time). If you still need to, you should plan on pulling your boat out of the water at least twice to three times during the boating season. Algae and debris tend to cling to the aluminum tubes, dragging the speed of the boat down.

Add a Third Pontoon

There's no question that three tubes are better than two tubes on pontoons. The middle tube can help provide stability and displace the water. Adding a new aluminum tube can be expensive, starting at around $4000. Many owners prefer to sell their pontoon and purchase a different tri-toon.

Don’t Fill The Tank

If you don’t plan on being out for a long time, don’t fill the tank full. Gasoline weighs a lot, and those added pounds can slow the boat down. Make sure you have enough gas to do whatever you are planning, but don’t feel you must constantly keep the tank filled.

What Size Motor For A 20ft Pontoon Boat?
Jacob Collier

Jacob Collier

Born into a family of sailing enthusiasts, words like “ballast” and “jibing” were often a part of dinner conversations. These days Jacob sails a Hallberg-Rassy 44, having covered almost 6000 NM. While he’s made several voyages, his favorite one is the trip from California to Hawaii as it was his first fully independent voyage.

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