Towing a Boat: Those Pesky Regulations & Other Helpful Thoughts

Don’t neglect boat towing regulations. Your boating vacation can easily be spoiled by getting slapped with hefty fines or, far worse, causing an accident. Knowing the boat towing rules in your specific state – and all the states you plan to drive through – is essential before setting out on the open road. Although standard speed limits are posted, there are other important laws like maximum towing speeds – and as a driver, you’re responsible for knowing and abiding by them.


Many states have laws limiting the width of boats and the times and days of the week boats can be towed. It’s wise to check out the laws in the state you live in and the states you’ll be driving through.


If your boat is large, especially if you’re crossing state lines, it might be worth the investment to hire a professional. See “Overland Transport” in the Marine Service Index for area service providers.


Maximum Towing Speed

Increasing your speed always increases your risk of an accident, but when you’re towing, high speeds are exponentially more dangerous. This is why maximum towing speed may be lower than the stated speed limit. In Alaska, for instance, it’s a mere 45 mph. However, in Idaho, New Mexico, and South Dakota, it is 75 mph. Of course, the roads out west tend to be straight and traffic lighter. Other states fall somewhere in between, with both Carolinas coming in with a 55 mph maximum – unless otherwise posted.


Maximum Boat Length

Although many states don’t specify this, some do, with South Carolina pegging as one of the strictest, capping boat length at 35-feet. Most, however, allow 40-feet or more. North Carolina doesn’t specify maximum boat length, but does require that the maximum combined length of tow vehicle, trailer and boat be 60-feet or less. Larger configurations require special permits and you’ll probably want to call a professional hauler if you live in that world. (Again, see Overland Transport.)


Maximum Boat Width

Forty-six states and the District of Columbia do NOT require a wide-load permit for boats-in-tow if the trailer width is 8’6” (102”) or less.


North Carolina deviates (Imagine that!), and allows boats on trailers up to 10-feet wide (120-inches) to be towed without a permit. If your total width falls between 102-inches and the maximum 120-inches, you’ll need two working amber lamps on the widest points to clearly mark outside dimensions.


Towing a boat or a boat trailer 114-to-120-inches can only happen (legally) during daylight hours.


Towing a boat with a wider beam will require a wide-load permit issued on a state-by-state basis. If you plan to cross state lines, you’ll need to know the rules. The authorities worry about the boats and trailers extending over the line on two-lane roads, which could be especially dangerous.


Imagine two wide loads meeting on South Island Road below Georgetown, coming to and from the ironically named South Island Landing, or those same two vehicles facing off on Wateree Dam Rd, near the Buck Hill Access on Lake Wateree. Could be trouble.

Also, keep in mind that Smokey will sometimes, probably depending on your attitude, count those Dumbo ears you call side view mirrors when calculating your maximum width.


Maximum Boat Height

In Michigan, your boat height needs to be as low as 12.5-feet, but in most other states, boats can be 13.5-to-14-feet. In both Carolinas you can go to 13’6”. This requirement has much to do with bridge clearances, so you should really pay attention.


Maximum Overall Length

I started down this road above, under “Maximum Boat Length,” which is the length of the trailer, boat and the towing vehicle from end-to-end. This can range from 53-feet in Mississippi to 75-feet in West Virginia and other states. South Carolina doesn’t specify an overall length. In North Carolina, it’s 60-feet. Again, larger configurations require special permitting.



The weight a trailer carries is the deciding factor as to whether brakes are required. Of course, the rules vary state-by-state (Isn’t that special?), but thirty-five, including South Carolina, require brakes for boat trailers carrying 3,000 pounds or more. In North Carolina, the brakes are applied at 4,000 pounds. A few states, like Florida and Pennsylvania, require brakes on all axles if pulling a tandem or triple-axle trailer.


Safe braking is especially important when towing – sudden breaking feels vastly different with a huge load tacked on behind you.


Other Important Stuff

Other things to consider are safety chains (required in both Carolinas) connecting the vehicle and boat in an X below the hitch-mount. They should be short enough so they don’t touch the ground, and long enough so they don’t restrict turning.


You’ll also want to consider a breakaway kit to protect you during an incident where the hitch mount accidentally separates. South Carolina requires breakaway control. North Carolina doesn’t address this. If you’re planning to haul your boat regularly, it’s not a bad idea or a huge investment to add this safety device to your trailer frame.


A competent driver can correct certain conditions, like trailer sway, but you’ll have absolutely no control over a loose trailer. Once it separates from the tow vehicle, unless it’s equipped with a functional breakaway kit, the trailer will continue moving forward until it either loses momentum or until it hits something else. That would be unpleasant.


Good marine supply and auto parts stores carry breakaway kits. Also, see the Marine Service Index for a list of Marine Accessories shops in our area.


Don’t forget the simple stuff, like lights, including a license light, tail lights, brake lights, clearance lights, turn signals and reflectors. It’s also a good idea to carry a spare tire for your trailer, along with the tools you’ll need to change it. Oh, and be sure your trailer jack (You do have a trailer jack, right?) can handle the combined load of your trailer and you boat.

By Win Minter and Mike Aldridge

Ensure your trailer wheel bearings are greased and in good shape. And check the winch strap (A winch strap can’t possibly be as fun as it sounds!), wire or cable is in good shape. Remember to connect the safety chain to the boat bow eye, once the boat is winched onto the trailer, as a fail-safe in the event the winch slips. Having your boat slide off the trailer onto the ramp can really ruin your day.


Finally, make sure you have tie-downs and flares. And then there’s insurance – there’s more than one kind of boat insurance. There’s even more than one kind of boat towing insurance. (See Marine Insurance providers in the Marine Service Index.) Finally, if you do have a boat that exceeds specifications, you probably don’t have to worry about avoiding certain states or breaking out the chainsaw – you’ll just need a special permit.


And More On Brakes

Yes, they’re that important.


When you’re towing a boat behind your vehicle, adding a couple thousand pounds onto the back makes everything a little more complicated. This additional weight makes itself known during almost every stage of a trip, but perhaps none so much as when you need to hit the brakes.


One of the reasons braking while towing is such a challenge comes from the notion of inertia – if something is resting, it tends to stay at rest. If something is moving, it tends to stay moving unless another force interferes with its motion.


Braking a trailer, especially if it doesn’t have any brakes of its own, is messing with its inertia in a big way. The tow vehicle might be slowing down, but the trailer is still raring to go, and this can cause it to swing dangerously. Also, any cargo that’s not strapped down will probably go flying.


Trailers can have a couple of different kinds of brakes, especially for heavier payloads, and these brakes are often required by law. When your goal is to achieve the safest possible braking experience, trailer brakes are definitely recommended.


Trailer brakes generally fall into two categories:


Electric brakes

These are usually disc brakes or drum brakes – the key is that they’re electrically activated by the driver of the tow vehicle. Wiring from the tow vehicle’s electrical system runs through a controller located between the two vehicles and signals the brakes of the trailer as needed. The driver can manually activate the electric brakes if the trailer begins to sway – or the brakes can be set to function automatically.


Hydraulic Surge Brakes

These are not specifically driver-controlled; they kick into effect automatically whenever the driver slows the tow vehicle. This happens because of inertia, with the surge brakes working hydraulically through the hitch. As the tow vehicle slows, the trailer presses harder against the hitch and compresses the braking actuator. The more the tow vehicle decelerates, the more stopping power the surge brakes generate.

If you have too much weight on the hitch or a load with a high center of gravity, slamming on the brakes can send the front end of your trailer into dive, taking your tow vehicle’s rear axle down with it. Not good.


Take the time to make certain everything’s stowed carefully. Some of the worst things you can do while towing a trailer are driving too fast or following too close, let alone ride someone’s bumper. Stopping with a trailer takes roughly double the time it takes to stop a solo vehicle, and it can take even longer depending on the weight of the load.


Plus, with more speed you get more sway (That exciting swing from side-to-side). If you do experience sway, taking your foot off the gas and gently applying the trailer brakes can help ease this movement; slamming on the brakes of the tow vehicle can be a disaster. Always keep your driving slow and controlled, with ample distance between you and anyone you’re following.


Another thing you want to keep in mind is the use of engine braking, also commonly called compression braking. Engine braking (using lower gears to slow a vehicle instead of the brakes) not only helps your brakes last longer, it also spares them from overheating, something that happens much more quickly when you add the weight of a trailer to a vehicle.


If you’re doing a lot of braking, say in order to go down a hill, you’ll probably want to practice engine braking along the way. Keep in mind, too, that some localities prohibit engine brakes since, especially in larger vehicles, this technique can be noisy.


You can use engine braking at other points in your drive as well. Your brakes will last longer and you’ll know they’ll be there when you need them. But over time, it will increase the wear and tear on other parts of your vehicle, as well as cost you more in fuel.


You don’t ever want to keep your foot resting on the brake pedal, a technique my mother likes to employ, when you aren’t trying to slow down. The smallest pressure will cause the brakes to operate at a low level and wear them out that much faster.


Otherwise, hitch that trailer up and haul your boat with you. There is big water to explore and fun to be had. Knowing the rules of the road will help you steer clear of accidents and avoid buzz-killing run-ins with the constabulary.

Pictured above is the RAM 1500 Eco-Diesel with a 3.0-Liter V6 engine and a maximum towing capacity of 9,050-lbs. the diesel engine has plenty of torque and a built-in trailer brake controller that works on trailers with electric brakes. See the entire line of RAM trucks at Conway Chrysler Dodge Jeep RAM in, well, Conway. Visit for more info. The Supreme tow boat this 1500 is hauling is available from Huntley Marine in Pineville NC. You can find them at


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