exceeding max hp rating on boat

Exceeding Max HP Rating on Boat: All You Need to Know!


Every vehicle that exists has certain limiting factors affiliated with them. For motor-based engines, horsepower is a limiting factor. Quite surprisingly, boats also have this limitation.

Nowadays, people are in a dilemma about the horsepower rating. Especially, people are curious about exceeding horsepower.

So, should you be exceeding max hp rating on boat?

This depends on you. You’ll get a more powerful and fast boat by exceeding the maximum horsepower of the boat. However, you might be sacrificing the insurance coverage of your favorite boat. If you’re overpowering the boat, calculate its max horsepower and upgrade it at a marine shop!

This is not everything you will need. Read till the end to know more. By reading this article, you can be sure about the dos and dont’s of boat horsepower! 

What is Max HP Rating on a Boat?

Boats require a lot of aspects to be checked off before taking it for a ride. Like the maximum number of people the boat can take, the maximum load it can take, etc. 

We should be familiar with what horsepower is. Speaking of horsepower, there is a maximum horsepower rating on boats. This determines the amount of horsepower a boat can have. There are certain limiting factors to this max horsepower settings. 

Now you might ask, why do boats have a max hp rating

Well, this was instituted to make sure that no boats were using too much power. Improper engines and unreasonable power may cause the boat not to float normally. That is why the manufacturers were bound to put a max hp rating on boats. This results in reduced power waste and increased safety. 

All this information might have you intrigued for knowing the procedure of calculating horsepower. Well, I can help you with that matter.

In the next segment, I have explained the full procedure of horsepower calculation for boats. Give it a good read!

How to Calculate Maximum Horsepower of a Boat?

You can know the maximum horsepower of a boat by using its width and length. Multiplying them will give you the boat’s square footage. 

If you don’t know the height and width of your boat, don’t worry. You can manually measure them using a measuring tape.

Here are some good quality measure tape recommendations for you-

Product 1
Product 2

By using these tapes, you can get accurate measurements.

After measuring, figure out the square footage. It will ultimately dictate the maximum horsepower of your boat. To help you out, here is a maximum horsepower chart for you-

Square Footage (feet) Maximum Horsepower (HP)
35 + 3
36 – 39 5.5
40 – 42 7.5
43 – 45 10
46 – 52 15

This is how you can find out the maximum horsepower of your boat. Aside from this, the boat should have stickers mentioning the maximum horsepower.

Now that we know the basics of the maximum horsepower, let’s dive deeper. You may be interested in increasing the horsepower of your boat.

But the question is, what happens if you overpower a boat? Read the following segment for the answer!

What Happens by Exceeding the Maximum Horsepower of a Boat?

Overpowering your boat can be considered an upgrade. Usually, when you overpower a boat, the specs, engine size, weight, etc stay the same. The only thing that changes is some horsepower over the limit.

This extra horsepower helps with the boat’s speed and power. Many people relate horsepower with performance, which is a logical equivalence. For example, the speed of 90HP boats will be lower than a 120HP boat.

So technically the more horsepower your boat has, the better it can perform. However, it does have a couple of downsides. Some consider exceeding boat hp rating as a risky act.

In exchange for overpowering the boat, you can lose the insurance coverage for it. According to the documentaries, your insurance will only cover the maximum horsepower.

If the horsepower goes beyond the maximum amount, it is out of their legislation. There are cases where the insurance company provides insurance based on the RPM. 

Yet in most cases, overpowering boats result in loss of insurance. So if you’re okay with that, you are good to go. 

Also, make sure that your boat is fit for the upgrade. For example, if you have an outboard and the outboard’s losing power under load, upgrade it. 

Many people have questions about the legality of overpowering a boat. Well, it is legal for you but not for the manufacturers. The coast guard guidelines are applicable for the boat manufacturers.

After reading all this info, chances are you’re interested in overpowering your boat. But how to increase the HP rating on boat? Check the next section for the answer.

How to Increase HP Rating on Boat?

Upgrading the horsepower rating of your boat will require some calculations. These calculations circulate around the transom and the weight of the boat.
If you are unsure about these, the easiest thing you can do is call your boat manufacturer. After you specify your boat model, year, and other information, they’ll approve or disapprove the upgrade. 

In most cases, the size of the boat is not the concern. The new engine of your boat will consist of a newer jet size and better electronic tuning. The weight will not increase necessarily.

After you’ve confirmed with the manufacturer, you can go to the nearest marine shop. Just buy a stronger engine with higher horsepower and fit it in your boat. 

After that, all that is left is to enjoy your new and powerful boat!


What is a compliance notice on a boat?

The compliance notice on a boat states if the vessel complies with the construction requirements. These are known as “capacity labels”. The reason behind this naming is, that this compliance notice also states the max capacity of boats. It shows the maximum number of people that can safely get on the boat. 

What size motor can I put on my boat?

You can know the required size of your motor by the size and weight of your boat. It will also let you know about the HP requirement. For every 25 – 40 lbs, you will need 1 HP. That’s the rule of thumb. As an example, if your boat is 1600 lbs, you will need a 64 – 40 horsepower engine. This is also the safest way!

Why do cruise ships go so slow?

Cruise ships go so slow because the ships are required to reach the dock at the exact time. If the cruise ship arrives early at the dock, it will require docking fees. Also, the cruise ships tend to maintain a steady pace throughout the entire ride. This is because cruise ships are heavier than regular ships.

The Final Words

This is the final reach of this article. Hopefully, now you know the reasons behind an exceeding max hp rating on boat

Boat peripherals can always be changed. So if you cannot fix it, replacement is always an option!

Good luck.

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