Whether you are buying a new boat or already own a boat, it’s important to figure out the “how much horsepower do I need for my boat” question, as it can greatly affect your boating experience and could be a big factor to determine the success of your fishing trips.
However, it’s a tricky question in terms of how much horsepower do you need for your boat as it is actually decided by many factors including the boat load, boat type/weight, hull design, the desired speed and range, and etc.
Overpowered could be dangerous (and void the warranty) and underpowered could spoil the fun and you might end up with an inefficient trip.
In this post, I will discuss how much horsepower does a boat need to give you a satisfying speed including the 14/16-foot boats, 16-foot aluminum boats, 18-foot fiberglass boats, 20 ft sailboats, etc, with a recommended horsepower table.
We are breaking down the complex question into 3 different parts including how much HP a boat need with trolling motors, electric outboards, and petrol outboards.
Table of content:
- How Much HP Your Boat Need with Trolling Motors
- How Much Horsepower Do You Need with Electric Outboards
- How Much HP for Your Boat with Petrol Outboards
- Other Burning Questions About Outboard Motor Size
How Much HP Your Boat Need with Trolling Motors
Let’s start with the trolling motors which are usually measured with thrust by lbs instead of hp. It’s a perfect tool for fishing especially on the electric-only waters.
What size trolling motor do I need for my boat? Is there a general horsepower to weight ratio formula for boats? The answer is YES.
Usually it’s recommended to get at least 2 lbs. of thrust for every 100 lbs. of fully loaded boat weight (including people and gear).
Here is a quick table for your reference in terms of how to determine what size trolling motor you need for your boat:
| Boat Weight (in pounds) | Minimum Trolling Motor Size (pounds of thrust) | Voltage | Max Boat Length (in feet) |
| 1,500 or below | 30 | 12 | 14 |
| 1,500 to 2,000 | 40 – 45 | 12 | 15 to 18 |
| 2,000 to 2,500 | 50 – 55 | 12 | 12 to 21 |
| 2,500 to 3,500 | 70 | 24 | 23 |
| 3,500 to 4,000 | 80 | 24 | 25 |
| 4,000 to 5,000 | 101 – 112 | 36 | 25 |
And as a general rule a little more thrust is always suggested to ensure proper boat performance in high wind and current conditions.
Not sure what the thrust of power means? Check out this post to learn how much horsepower you will get from it.
How Much Horsepower Do You Need with Electric Outboards
When it comes to electric outboards motors, the measurement is a little bit different since you get a larger power range.
So is there a ratio between the size and weight of a boat and the horsepower its outboard should have? You might also want a quick reference with the boat weight as a reference.
Here is a table of the outboard motor size with different range of boat weight and boat type:
| Boat Weight/Type | Horsepower Range |
| Kayaks, canoes and very light boats | 1 – 3 hp |
| Tenders, dinghies and daysailers up to 1.5 tons | 1.5 – 3 hp |
| Motorboats and sailboats up to 10 tons | 5 – 20 hp |
| Powerful motorboats | 40 – 80 hp |
Here are also some tips if you are still not sure about how much horsepower is needed for your boat:
- Refer to the capacity plate for its max horsepower. All boats since 1972 should have a plate on it with the maximum hp listed on it. Make sure the boat is not overpowered as it might void the warranty.
- Add some horsepower if you are having extra person on boat or need to deal with heavy wind or current.
- Compare the size of the motor to as many other boats with the same hull as you can.
- Talk to the distributor and ask them for professional advices.
- Take the outboard for a sea trial to see how it handles (preferably in fairly poor conditions).
You may also purchase the boat and outboard in packages so that everything is included. It would be cheaper and also eliminate the questions about the motor size.
How Much HP for Your Boat with Petrol Outboards
The petrol outboards are for larger vessels requiring even higher horsepower. That’s to say if you are looking for the power range at over 80 hp, you will probably get a gas outboard.
Again, you might ask: Is there a general horsepower to weight ratio formula for boats?
There is no exact answer, but generally speaking, you should have between 40 and 25 pounds of weight for each horsepower. And in most cases, 8-20 hp motors will provide plenty of power to effectively propel your boat, and you’ll find you get better fuel efficiency as an added bonus.
Another way to roughly determine how much horsepower you need for the boat is to check the capacity plate and you will want at least 50% of that rating or higher. For example, if your boat’s capacity plate lists a 40 hp maximum, a 20 hp motor should do you fine.
However some might like to go toward the upper end of the recommended HP range.
Other Burning Questions
1. How much horsepower do I need to pull a skier or a tuber?
It actually depends on what kind of boat you’ve got. For example, for the 24-foot pontoon boat, to be safe you would need at least a 90hp engine to satisfy the tubers in your family.
2. Can you exceed max HP rating?
The MFG would probably void all warranty if you did it. That’s to say if an accident occurred, it will not help your case if the hp was overrated. You might have issues with transom strength both due to the weight and the hp.
Bottom Line
How much horsepower a boat need is a complex question. You should have a clear idea about what you want your boating experience to look and feel like to get an accurate answer to how much HP your boat needs.
And it further breaks down to how many people you want to take out, and how fast you want to go with those people. Also consider what watersports you might participate in, and the age and experience level of any watersport participants