Thinking About Over Powering Your Boat? Don't.
Outboard HP Ratings for Tiller-Steer Boats
I recently water-tested a War Eagle 860 LDV Pod Seating Tiller with a customer, rigged with a Yamaha F70 4-Stroke Outboard. After running it, turning, twisting, and trimming it up tight to get the most speed, the customer commented “this boat handles well with a 70-horsepower Yamaha outboard, but I want a VF90 SHO on it? We said no and he wanted to know why. I did not want to sound contrite, but said “Because that’s all the United States Coast Guard (USCG) Cap Tag allows it to be.” He bought the boat with the 70hp motor, but the funny thing was, though, that this same War Eagle 860 center or side console is max rated for a 115 hp motor. He, like most that we talk with on a daily basis, did not understand how a steering wheel makes that much of a difference. Truth is, we agree with him, but at the end of the day, the ultimate authority is the US Coast Guard. They set the rule and they are the boss.
That said, here’s how the rules work.
For any outboard-powered boat over 20 feet in length, the maximum horsepower rating is at the discretion of the boat builder. If the boat is less than 20 feet long, the power rating is determined by a USCG formula.
- For remote-steering boats (i.e. steering wheels), the formula is: (stern Width in decimal feet x Length in decimal feet x 2) – 90 = Max. HP Rating (rounded up to nearest 5hp).
- For tiller-steer boats with a flat bottom (like a plain jon boat), it is (W x L x 0.5) – 15 = max. horsepower (rounded up to nearest 5hp).
- For all other tiller-steer boats: (W x L X 0.8) – 25 = max. horsepower (rounded up to nearest 5hp).
Now, to the USCG, it seemed logical to permit more HP when the operator had the mechanical advantage of steering the boat with a steering wheel or stick, versus a tiller-steer. Or at least it did until the advent of power-assist steering systems for tiller outboards, like the Hydraulic Tiller Steering units now available. If the tiller motor is equipped with hydraulic steering assist, why couldn’t the tiller HP rating be increased a little bit?
Many boat companies have numerous discussions with the Coast Guard on that subject and all say the same thing: “The Coast Guard will not budge.” And, after all, they are the boss when it comes to capacity tag ratings.
Po Chang, a civilian boating safety engineer with the Coast Guard, explains that they have three main concerns when considering max power for tiller- versus remote-steered boats.
The first is operator placement.
“With the operator sitting further aft at the tiller, the boat is not in ideal trim,” says Chang. “He also can’t see forward as well, and the boat may be more prone to porpoise.”
The second concern, says Chang, is operator security.
“A steering wheel provides a brace for both hands, and the seat offers additional stability, that the operator of the tiller boat does not have,” explains Chang. “The tiller operator is just hanging on the gunwale with his right hand.”
Finally, there’s the difference in reaction to helm input between the two systems.
“With a steering wheel, it takes a pretty deliberate motion to change course,” says Chang. “The tiller is connected directly to the motor, and it’s much easier to make an inadvertent course change.” But adding power assist to the tiller does not really address any of these issues. Chang also explained the history of the outboard power rating formulas, which date back to the early 1970s.
“The goal was to come up with a simple formula that would apply to a variety of boats, and would be easy for the boat builders to use,” says Chang. “It was an entirely subjective process. Engineers ran about 150 different boats with increasing amounts of power, executing a quick, 180-degree turn and a course-avoidance maneuver. Basically, when they no longer felt comfortable doing that, they’d reached the power limit for that boat. With that experience in hand, they devised a formula that would work with a typical boat.”
So why does the power-rating mandate end at 20 feet in length?
“The 20-foot limit is based on accident statistics,” says Chang. “Once a boat is 20 feet long, accident incidents go way down. There are fewer boats of that size on the water, and they are less likely to swamp or to be tossed out of control by a large wake, and people don’t fall overboard as easily.”
Whether you agree or disagree with the USCG arguments and concerns, it does makes sense to us. We often see boats over-powered of the UCGG Cap Tag, That is certainly a choice. But while everyone likes to go fast (duck hunters especially to get to the hole first), there are some other considerations that come into play:
- Over powering your boat excess of the USCG CAP Tag VOIDS your boat’s hull warranty. To some that may not matter, but consider that many boats have a limited LIFETIME Hull Warranty. LIFETIME. Overpower and you are throwing away that warranty. Is it worth it? Only you can decide, but, as a dealer, we feel that warranties are an important part of any boat purchase, more so down the road when you may have a problem, only to find that you don’t have the warranty any more because of your HP choice.
- Increased hull cracks and stress fractures. With the increased torque of higher horse power, we often see a significant increase in broken welds, stress fractures in the aluminum, twisted hulls, hooks, and broken transoms. In one case, we saw a popular Arkansas Duck Boat have a transom actually fall of the back of the boat from the stress. And, with no warranty, a sad day for the owner.
- Dealers can’t overpower your boat. Boat dealers have various licenses, regulations, and requirements that they must follow and adhere to. All commercial dealer insurance policies prohibit dealers from over powering boats, as does the State and USCG. Dealers can choose to over power, but there is NO coverage if something happens, and the dealer becomes responsible. And something WILL happen. You know as well as we do that everyone wants to sue, even for their own poor decisions. No reputable dealer will ever over power a boat, knowing they have no insurance coverage if someone is injured, maimed, killed, or causes damage, and that the state and USCG will be all over them. Poor choices leads to poor results, no matter who makes the choice.
- Your Insurance Liability. We don’t want to get too deep in the weeds on this one, but almost all insurance companies will write your coverage without asking a lot of questions, regardless of what HP you have on the back. That is fine and good until you have a claim and THEN discover your coverage is being cancelled when the adjuster researches your unit and finds out it was overpowered. It doen't matter until it does - and then it is too late. Read your insurance policy (no one ever does), because all include underwriting language about modified and over powered boats being insurable. Over powering boats put them into the category of “racing” units. By not disclosing that you over powered your boat, you have “materially mis-represented” your unit to the insurance company, (i.e., the company does NOT have to pay the claim, and can cancel your coverage.) The insurance company may reserve the right to feel bad for you, but you are flat out of luck. Pay the claim yourself. We have seen this happen several times.
The bottom line is that everyone has an opinion about power, brands, and HP. Hunters, fishermen, and boats love to argue, but ultimately, though, following the Manufacturer USCG Cap Tag for horsepower is the best bet for everyone to keep your warranty, be safe, and cover your butt with insurance when something happens.
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