How Fast Does A 70 HP Boat Go? | LakeWizard

Key Takeaways

  • The speed of a 70 hp boat can reach up to 56 mph
  • A fair amount of factors, like water, load, and size affect how much hp needed
  • A Yamaha motor might be the best bang for your buck on the boat
  • If you want a little more speed out of your boat, try upgrading your lower hp to a 70 hp

Going fast on a boat is usually a hot selling point for most boat owners. If speed is what you desire, then how fast does a 70 hp boat go?

The speed of a 70 hp boat depends on a number of factors, including the weight of the boat, the design of the hull, and the conditions of the water. Typically, a 70 hp boat will top out at speeds of around 40 miles per hour, with some boats going around 56 miles per hour.

While speed is not everything you need for a boat, it is a fun experience especially if you have the motors to do it. As you will read, you can see how the different factors affect the speed and if certain motors are right for your boat.

Table of contents


Factors Determining Boat Speed

You are probably thinking, if it is just me, why should I care about boat speed? If you expect to cover some ground efficiently on the water, a vessel equipped with ample horsepower will serve you well. The amount of power required to increase your speed, however, varies depending on the characteristics of your boat and its weight.

Load of Boat

The weight of a boat is a major determinant in figuring out the horsepower required to achieve a desired speed. On average, for every 1,000 pounds a boat weighs, the difference you will likely see is a decrease in speed, so expect 10 to 20 miles per hour less.

It is essential to remember that when calculating how much a boat weighs, it is not just the manufacturer's listed weight that matters. Additional factors such as the number of passengers on board, equipment, and any additional gear all play a role in determining a full load and how it messes with your speed.

While gas may be the least of your problems, fuel adds weight to an already heavy boat. If your boat has too much weight on board, expect to burn more fuel to reach desired speeds. It is crucial to be mindful of the weight capacity of your boat so that you do not exceed the recommendation to ensure safety while on the water and to save on gas.

Boat Design

It is natural that a boat geared towards speed is able to extract more performance from its horsepower than a vessel designed for cruising. Speedboats and other top quality cruisers typically are able to obtain much faster speeds with the same horsepower rating in comparison to regular cruisers or other family boats.

For example, check out this list for top speeds of some 70 hp boats:

  • Cruiser/Passenger weighing 1,000 pounds has average speeds of 40 mph.
  • High-Speed Cruiser weighing 1,000 pounds has a top speed of 50 mph.
  • Racing Boat weighing 1,000 pounds has a top speed of 56 mph.

Different hulls make an impact on speed, making some boats slow. The shape of the hull and how the weight is distributed, as well as the engine, play a role in speed.

Plenty of boats prioritize different aspects, such as speed or comfort, so there can be trade-offs in terms of overall performance. For example, racing boats are usually meant for speed, which might not have the comfort features as cruiser boats, which have designs with comfort in mind.

Choosing a Motor

Honda and Yamaha are two common motor options boaters will likely see. If upgrading, you should really decide based on price and potentially the warranties that come with the motor.

Yamaha is a great motor for long term use, as these typically last up to 300 hours. Honda also makes a great motor, which is geared towards newbies on a boat.

If you are buying a boat, you should try a wide open throttle test (wot rpm) with a light load on board. This way you can see exactly how efficient your boat is and test its speed.

Picking a Safe Horsepower

While it may be exciting to weigh your options for a 70 hp boat or engine, it is important to remember that not all boats are designed to handle such power levels. This can not only lead to a dangerous and unstable ride, but it can also cause damage or even destruction of the boat if it is not designed to withstand the stresses of high speeds.

Moreover, over-powering boats are prone to flipping over during acceleration or while on a plane. Therefore, it is crucial to consider the manufacturer's recommendations when determining the appropriate horsepower for your boat.

Determining Good Horsepower for Your Boat

Picking the logical horsepower for your boat will unlock the ability to enjoy the waters while remaining safe. Having the correct motors will help your boat run at optimal conditions and last longer. Engines with higher power usually weigh more, so operating them often at lower power might not be the best for energy consumption.

There are several factors to consider when determining the best horsepower, so you do not have to guess for your boat. These include:

Size of the Boat

The larger the boat, the more horsepower it will need to move efficiently. You are not going to need a 100 hp engine to power a 10 footer, but might need one if you have a boat over 30 feet.

Type of Boat

The type of boat you have, such as a fishing boat, a pontoon boat, or a speedboat, will influence the amount of horsepower you need. Not all boats require or can handle an upgrade in engine power.

Number of Passengers

The more passengers you have, the more rpm you will need to move the loaded boat efficiently. Assume each person weighs 140 pounds and you have four people total on board, that adds 560 pounds to the boat’s weight. This means you need the correct amount of horsepower to move appropriately on a loaded vessel.

Water and Weather Conditions

If you will be boating in calm waters, you will need less horsepower than if you will be boating in rough waters. If the wind is in your favor, or against you, this is also a factor. You will likely see a big difference in your top speeds for just those two conditions alone.

Towing Capacity

If you plan to tow water toys or other equipment, you will need more horsepower to pull them. These include water sports activities for the wife or family, or other recreational uses commonly done on a lake to pull something with your boat. Just be sure you are not trying to pull a heavy load like a barge with your boat.

Your Personal Preference

Your own desired top speed and boat experience also play a role in deciding the horsepower. If you believe upgrading to a 70 hp boat is worth it, consult with a marine mechanic or professional for an accurate assessment of what horsepower is ideal for your boat. You might be surprised what a difference it makes going from a 50 hp motor to a higher one.