The quest for greater speed and more power is on the minds of many boaters these days but it is important to remember that there are potential safety and structural issues that could result from overpowering your boat.
Bigger doesn’t always mean better.
Many boat owners are considering repowering boats they own or used boats they are thinking of buying. Adding a higher horsepower motor can be an option but there are certain things that need to be considered prior to doing so. It’s best to avoid overpowering your boat.
All boats are required to have a maximum HP rating and this can usually be found on a plaque located on the vessel.
If you plan on going to a larger than stated maximum horsepower you will be doing so at your own risk and should proceed with caution. The manufacturer has determined this rating based on the engineering of the craft, the handling characteristics and the weight and balance of the vessel.
When the boat was designed the transom and structure such as stringers and bulkheads were all designed with a certain power limit applied to them. If one were to put a larger than rated motor on the boat there would be pressure and stresses applied that may be over the acceptable range for the boat and serious damage could occur. Just minimal increases in horsepower of an outboard can create tremendous pressure and torque on the transom, resulting in potentially catastrophic damage to the hull.
If a higher than rated horsepower is installed, reinforcing the transom and hull structure may also be required.
Pressure on the steering system and others could also be a factor so make sure all of your boats systems can handle the extra power.
It used to be true that if you went with a higher horsepower motor you were also adding weight to the transom that could affect the balance of the boat. This is not necessarily true with newer and lighter outboards where weight has gone down and horsepower has gone up. However, it is important to ensure that weight is considered as a heavier motor could render self-draining cockpits useless and create wet cockpits as water enters scuppers from a sagging transom.
Going from a single motor to multiples also creates potential weight issues along with other issues so check with the manufacture.
One often-overlooked potential issue with overpowering your boat is that your insurance company may not cover your vessel should you need to file a claim.
Most companies will use the boat’s maximum rating as its limit for coverage and you could find yourself in a bad situation should they discover that the engine is bigger than recommended by the manufacturer. Some insurance companies may make exceptions (for an additional premium) so you should check first.
You may also want to check your local and state laws as in some areas overpowering may be illegal.
Even if it’s not, should an accident occur you may be found as negligent and open yourself to a law suit in the event of damages.
No matter what outboard you end up with, it is important to consider all factors before exceeding the maximum power recommendations of the boat’s manufacturer. More power could translate to more problems so proceed with caution.
If you love power, you should also check out the story that Glenn Hayes did on Seven Marine. “The Most Powerful Outboard Motor Ever!”
what about jet engines? There is no stress on the transom whatsoever. Is i just a biggest that will fit scenario? I have a 50hp on my 10 foot mini cruiser speedboat the whole boat leaves the water at 45mph and only the prop is still in the water. Its border line flying over the water.
I have old jhonson outboard motor 200hp want to put into my 16’ fiberglass boats is this possible and what is the downside?
Your boat’s total weight is the basic foundation when finding the appropriate amount of horsepower. The rule of thumb dictates that there should be 25 to 50 pounds for every single horsepower.