As a boat owner, you have the luxury of doing little experiments with your watercraft. But don’t get too excited and forget important safety measures, especially when it comes to vital components such as the engines.
Before repowering your boat, you need to examine many factors, one of which is the vessel’s horsepower limit. Where can you find the maximum horsepower for your boat?
Useful information can be found on a capacity plate near the steering control. This is the maximum engine power and speed your watercraft is designed to endure. When attempting to exceed this limit, you face many costs: boat damages, law violations, insurance denial, and even fatal accidents.
Table of Contents
- Where Can You Find the Maximum Horsepower for Your Boat?
- What Does the Boat Capacity Plate Look Like?
- How Much HP Does a Boat Need?
- How Do You Calculate Maximum Horsepower?
- What Factors Affect the Decision of Boat Horsepower?
Where Can You Find the Maximum Horsepower for Your Boat?
1. Where is it?
On boats longer than 20 feet, you will find a capacity plate inside the hull within the captain’s area. This label must carry precise information about the capacity of the boat, including the number of people, weight, and horsepower limits. Federal law applies this rule to all manufacturers in the U.S.
But where do I find this information on boat less than 6m or imported watercraft? You can check the HP rating for boats in the owner’s manual. Most manufacturers provide online owner’s manuals along with physical copies, so rest assured that you won’t have much trouble finding one.
In the worst-case scenarios, you can reach out to the brand via email or phone to ask for the recommended horsepower for boats.
2. Why is it important?
The horsepower rating determines the power of a motor; the higher this number, the more powerful a motor is. Manufacturers dictate this rating based on the characteristics of the watercraft they built, such as its structure, weight, material, seakeeping ability, and speed potential.
Pontoons, for example, are built with flat bottoms and spacious decks with the purpose of holding family gatherings and cruising slowly on calm water bodies. Thus, pontoon horsepower ratings are often lower than those of tournament bass boats, which are designed for speed and sensitivity (150 vs. 300 hp on average).
Builders have calculated thoroughly before placing the information on the capacity plate on a boat. Keep in mind this limit when you decide to replace the current engine with a more powerful one. Exceeding the recommendation risks putting everyone on board and your vessel in jeopardy.
What Does the Boat Capacity Plate Look Like?
The capacity plate is a rectangular sticker or card titled U.S. Coast Guard Capacity Information. It carries information about the maximum number of people, maximum gross load, and maximum horsepower.
At the bottom of the capacity plate, you can find details on the boat’s model, serial number, and MRF (short for Manufacturer.)
Besides the horsepower, you’d want to keep the number of people on board and the total weight within the limits displayed on boats gross load capacity plate. Loading a boat past its weight capacity can cause it to swamp or capsize, leading to perilous repercussions.
How Much HP Does a Boat Need?
The answer to “How much HP does my boat need?” depends on your watercraft’s type, weight, size, and purpose.
RIBs and inflatables, for example, are super light and weight-sensitive. For such watercraft, the engine’s HP rating is not as important as its heft limit. You only need a 40-horsepower two-stroke motor for a RIB to cruise smoothly on the water.
On the other hand, fishing boats should be equipped with powerful engines to load all the heavy gear of an angler: fishing rods, bait buckets, live wells, ice boxes, and fuel for long trips. In general, one 60-HP engine is sufficient for a 16-foot aluminum fishing boat.
How Do You Calculate Maximum Horsepower?
If I build a homemade vessel, how do I calculate boat capacity by myself? Is there any specific boat capacity calculator equation?
A rough boat max HP calculator method is to use your watercraft’s area measurements. To begin, you need to measure the length by running the measuring tape along the center of the boat, starting from the most forward point of the hull to the transom.
Then, measure your boat’s width at the widest area. Once you have the figures, multiply them with each other to get a square footage number.
- Boats that are lower than 35 square feet should keep the engine below 3 HP.
- Boats that are between 36 and 39 square feet should keep the engine at 5.5 HP or less.
- Boats that are between 40 and 42 square feet should have an engine of ≤7.5 HP.
- Boats in the range of 43 to 45 square feet can have a 10-HP engine at maximum.
- Boats in the range of 46 to 52 square feet can have a 15-HP engine at maximum.
Another boat horsepower rating calculator method is to use your boat’s weight. Generally, one horsepower unit is needed for every 40 pounds. So, all you need to do is divide your boat’s weight by 40. Note that this weight should include the fuel, gear, people, and the engine itself.
What Factors Affect the Decision of Boat Horsepower?
Though you can get precise numbers from the boat motor size calculator we introduced above, the actual horsepower you need in real life fluctuates a lot. It depends on your need, the vessel’s purpose, the number of people you plan to board, the insurance policy, and state regulations.
1. Vessel purpose
A recreational fishing Jon boat might not need as much horsepower as a speed ski boat. So, your decision will depend largely on the boat’s purpose. Will you pull wakeboards? Will you need speed or power to navigate rough water bodies? Will you venture far out onto the sea or keep it close to shore?
You don’t want to invest in a powerful engine just to waste its potential and your money. Plus, chunky motors add significant weight to your small vessel and might slow down your trip.
2. Number of guests
How many people will you invite to come on your boat? If you intend to keep it low-key between you and your dog, the boat’s load will be reduced notably, considering that each person might weigh 150 pounds on average.
3. Insurance policy
The more powerful your boat is, the higher the insurance bill will be. So, don’t leave out this factor. Besides, you should check your agent’s policy before upgrading the engine. Most insurance types only cover a certain range of engine horsepower.
4. State regulations
In some states, overpowering a boat is deemed a legal violation and thus results in lawsuits and heavy fines. You must check the state regulations before repowering your watercraft.
To sum up, the capacity plate near the steering control is the answer to “Where can you find the maximum horsepower for your boat?” But you can also find the information in the owner’s manual, contact the manufacturer for an inquiry, or even calculate it yourself.
Speeding your boat through a vast body of water is fun and exciting, but don’t forget to put your and others’ safety first. Always consider the necessary precautions before altering your watercraft’s engine!
Working to create content for Marine Talk has always been a fascinating experience. I get to travel, absorb knowledge about boating, and tackle all the issues when we sail into freedom!