When purchasing a boat to use for water sports, one of the main questions you’ll need to ask is how much horsepower your boat needs to tow you .
Horsepower refers to the power that an engine produces, and the amount of horsepower required depends on a boat’s power to weight ratio.
Horsepower requirements depend on the size and weight of a boat and its load, the engine type (inboard or outboard), the sport/activity you do, and the weight and skill level of the person being towed behind the boat.
Towing a single tube is possible with 35HP. Skiing needs more power, and while a child can ski with 20HP, a heavier adult needs at least 60 HP on an appropriately sized boat. While you can wakeboard with as little as 25 HP, a quality wake generally requires a 135+HP loaded boat.
Boat owners often recommend 90 HP on a 16′ boat as the minimum for serious slalom skiing and wakeboarding on a fully loaded boat. 115 HP will generally be comfortable, while 75 HP may barely be enough.
Let’s take a look at some specific examples of the minimum horsepower requirements for different boat sizes, and uses.
Minimum horsepower for tubing/inflatables
Inflatable tubes don’t require as much power to get them gliding over the water. This is because they naturally float, and don’t dig into the water like a wakeboard or skis do. Tubes and kneeboards are the easiest towables to pull.
They also don’t require a popping-up action from the rider like with skiing and wakeboarding, which demands additional horsepower to initially bring the boat onto a plane while pulling the rider up into a standing position.
In contrast, trying to get skiers up with a 14′ aluminum boat with a 35HP motor is much harder since the boat is too light with insufficient power to make up for it. Such a boat can still tow a tuber, although the boat will typically get pulled in turns.
When turning at dramatic angles, the weight of the person on the tube can affect the boat’s momentum, forcing the boat to slide out of control, and at times come to a sudden stop. This can pose a safety threat to passengers on the boat and damage the engine.
Now, if you’re looking to pull an adult (or two children) weighing over 150lbs, you’ll need more horsepower and a heavier boat to compensate.
A 115HP engine on an appropriately sized boat with two passengers could tow two adults in a double-seater tube with ease.
Minimum horsepower for water skiing
Skiers need more power to pull them out of the water and maintain a planing speed. Additional horsepower helps the boat to cut through the water to create a clean space behind the boat.
Water skiing with < 50HP (e.g. 25-40HP)
As mentioned, towing a lightweight adult is possible behind a 14-foot tin boat with 35HP driving at around 25mph with the right propeller. However, the skiers’ experience will be limited with little room for improvement if the rider is looking to develop their skills.
It is even possible for a child to ski behind a 5-meter boat with a 20HP motor. The experience is minimal, however, with no ability to do carves and wake hops.
As soon as you try towing a heavier person, simply cutting across the wake at speed could pull the entire propeller of a small boat out of place, causing the boat to cavitate and lose control. This can even cause the driveshaft of a smaller boat to crack.
If you want to tow a skier with under 50 HP, you need to consider the overall weight of the boat including load. A 25-40 HP engine would match a 500 lb boat, and perhaps work with a 750lb boat.
However, anything above this (eg 1000 lbs) will be difficult to power with a 25-40 HP engine.
Water skiing behind 50-55 HP
A 16′ fiberglass boat with a 50 HP engine can typically tow a small adult skier with ease. This works best with teenagers, who are typically fit and weigh less than adults. A small boat will offer a decent skiing experience for riders under 130 lbs.
Pulling a heavier adult or teaching a beginner will generally be tricky with this little horsepower. Pulling a heavy skier can cause the boat to lose control. Over-acceleration to compensate for the weight can also cause the engine to overheat.
Towing a slalom skier with this type of HP is also a long shot. Slalom skiing generally requires speeds between 19 to 36 mph, vs 20-30 mph for doubles skiers.
Slalom skiing also requires fast deep water starts, hard to pull on a small boat loaded with people. A heavy, small boat with inadequate horsepower won’t have enough power to pull the skier out of the water and reach a plane quick enough.
Water skiing behind 60-65 HP
Between 60 and 65 HP is a solid amount of horsepower for a child skier, and also works for a larger adult on double skis at lower speeds of around 20 mph.
With a 60 HP boat loaded with passengers, it can be difficult for an adult skier to pop up, as it can take a long time to get the boat planing at a decent speed of between 20-30mph.
Waterstarts on a single ski, especially deep water starts, are a strenuous process for both the engine and the skier behind a 60-65HP boat.
Getting up on two skis and dropping one is possible, though the low power of the boat will make it difficult to stay up on a slalom ski.
Water skiing with 70 HP
70 HP is more than adequate to tow a traditional skier, tuber, or wakeboarder. With an appropriately sized boat for the horsepower, you can typically tow two skiers on double skis.
A 70 HP engine combined with a light boat and minimal load can also generally tow a 175lb slalom rider at a competitive level.
With more than 2 passengers on board, however, the boat will struggle to pull a slalom skier out of a deep-water start. You’ll need to pitch the propeller and trim as low as possible to give the boat extra stability as it pushes to reach a plane.
A lower pitch allows your engine to reach its maximum power at a lower speed. This is essential for power-driven deep-water pop-ups.
Water skiing with 90 HP and above
A 90 HP motor is the general minimum horsepower to use for a competent adult slalom skier.
A 115 HP engine paired with a 990 lb boat loaded with three passengers will be powerful enough to lift a 230 lb rider out of a deep start – although heavier riders typically struggle a bit to get up.
A classic Carlson Glastron CVX 16 paired with a 200 HP Johnson outboard engine will easily pull two 200lbs barefoot skiers up from a deep start.
That said, for larger skiers (traditional or slalom) over 200 lbs, an inboard ski boat is generally the best option. These boats are typically built with more powerful engines and low pitch propellers.
Minimum horsepower for wakeboarding
Wakeboarders ride at a slower speed than skiing – 16-19 mph vs 20-30 mph. Because a wakeboard planes over the water like the wing of an airplane, deep water starts don’t require that much speed.
Driving at a steady 16 mph, a competent wakeboarder is typically able to ride behind an aluminum Jon boat with a 25 HP engine.
If the rider has difficulty getting up, try positioning her not directly behind the boat. Make the rope tight, then drive off at an angle. This will help the boat pick up speed faster and then put tension in the line for pulling the wakeboarder out of the water.
A very small boat with low horsepower won’t create a worthy wake. You can drive around to cruise over your own wake, offering the opportunity for the wakeboarder to pop over the oncoming wake.
A heavier boat with a powerful engine and propeller that sits deeper in the water, with added passenger weight and ballast, will create a sizable and quality wake for a wakeboarder.
A 135 HP engine with 6 passengers will have enough power to pull a wakeboarder out of the water and reach a plane within 4 seconds and hold its speed. A set of smart tabs (trim stabilizing system) can help the boat reach a plane quicker.
Frequently asked questions
Minimum horsepower for tubing?
You can pull up to 150lbs on a single-seater tube with a 35 HP engine. The more powerful the engine, the more weight you’ll be able to tow. A 115 HP engine can easily tow two adults on a double-seater tube.
Is 135 HP enough for skiing?
A 135HP engine will provide enough power to pull a slalom skier out of a deep-water start. Combined with the right boat size and weight, a 135HP engine could even pull up two riders over 200lbs each.
Can a 115 HP motor pull a skier?
Yes, a 115HP engine with a loaded boat (3+ passengers) can pull a skier up to 230lbs.
Will a 50 HP motor pull a skier?
A 50HP motor attached to a small fiberglass or aluminum Jon boat would be able to tow a skier under 130lbs.
You will struggle pulling a slalom skier out of deep water with a 50HP engine. Pulling a heavy adult or inexperienced skier will be very hard.
Can you pull a tube with a 25 HP motor?
It’s possible to tow a tube with a 25 HP motor at slow speeds, however, any sudden turns and boat movements can cause the tube to pull and dictate the direction of the boat.
Can you pull a tube with a 15 HP outboard?
While it’s possible to tow a small child under 45lbs with a 15HP outboard engine, skiing behind a boat with such little engine power is typically challenging.
Can you pull a wakeboarder or 2-person inflatable with a 40, 50, 60 HP engine?
It’s possible to pull a single lightweight wakeboarder behind a 40 HP engine. However, the boat won’t create a big enough wake for a competent adult wakeboarder to enjoy.
A 60 HP engine could pull a two-person inflatable tube (e.g. two small children). However, if you’re looking to please a pair of adult tubers with some speed and adrenaline, you’ll need at least 90 HP – upwards of 115 HP will work best.