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June 16, 2024
Boat Trailering 101
Boating Capt Jerry Dilsaver Featured

Boat Trailering 101

David Owens discusses trailers

Reports from the National Marine Manufacturers Association show boat ownerships are increasing.  The statistics also show many of the new boats are being sold with trailers.  Trailers definitely give boat owners freedom on where to fish or boat, but that comes with some responsibility for selecting the correct trailer and maintaining it properly.  Good trailer selection and maintenance habits account for many excellent boating adventures, but incorrect choices and lackadaisical maintenance can result in potential outings being spoiled while waiting on the side of the road for assistance with a disabled trailer.

David Owens of Road King Trailers (, 828-670-8012) in Candor, N.C. and several salesmen and technicians from Doug Henry Chevrolet, Buick, GMC (, 252-753-7700) in Farmville were glad to offer tips to help make trailering your boat, or anything else, painless and worry free.  Readers should agree these simple steps for choosing, setting up and towing a trailer can make the trip to and from your favorite launching ramp an easy trip.

Owens said that matching the trailer to the boat is the first important step in safe and easy towing, but noted that understanding the metals used in trailer construction is important before sizing the trailer.  The basic and least corrosion resistant trailer material is painted steel.  This offers no corrosion resistance and should only be used in fresh water.  The middle grade of metal, which offers fair corrosion resistance if washed after each dunking, is galvanized steel.  Aluminum is the most corrosion resistant metal available for trailer construction and also offers the plus of being the lightest.

There are also standard and upgraded bolts, nuts, screws, connectors and lights packages.  Stainless steel is the least corrosive, with yellow zinc next, then galvanized and non coated fasteners should only be considered for freshwater or non-water use.

Back to matching the trailer to the boat.  The most obvious thing to match is the length of the boat.  If a trailer is too short, the boat will hang off and not be supported well.  Conversely, a trailer that is too long may not support the boat well and can make it difficult to secure the boat to the trailer.  Most trailers are classified with a 2-4 foot size range and finding the correct length should not be a problem.

The width of the boat is another consideration.  Boats have grown in width over the past two decades and even some of the runabouts, small center consoles, bay boats and such that used to be 7 1/2 to 8 feet wide are now 8 1/2 feet or more in width.  The trailer for these boats must be wider to balance them correctly.

The weight of your boat is another primary part for matching it to a trailer and will also factor into choosing an appropriate towing vehicle.  Every trailer has a maximum capacity and it is wise to give this some leeway.  As fishing equipment, skis, safety equipment, ice, water, food and such are added to the boat, it gets heavier.  Most folks realize this increases the boat’s weight, but they don’t realize how quickly the weight increases.

Mismatching the actual total weight of a boat and the maximum capacity of a trailer is where most incorrect fits occur and it is the one that is most likely to cause problems.  An overloaded trailer has potential for frame, axle, spring, and tire failure.

Let me emphasize that most boaters and fishermen seriously underestimate the weight of their boat.  The weight that the trailer will have to carry includes the boat, motor(s), brackets, jack plates, trolling motors, fuel, battery(s), safety equipment, fresh water, fishing gear, watersports gear, coolers, ice, accessories, and anything else left in the boat while on the road.  The odds are that most boaters will need a heavier capacity trailer than they thought.

A boat’s weight really does add up far faster than most folks realize.  For a hypothetical example, let’s start with a 22-24 foot center console boat the manufacturer lists the dry weight at 4,000 pounds.  Note that this isn’t considered a large boat to tow and many folks head out fishing pulling it behind a full-size SUV or pickup.

A pair of outboards add 800 to 1,200 pounds, 200 gallons of gasoline (6.3 pounds per gallon) adds 1,260 pounds, a trio of heavy-duty marine batteries (2 starting and 1 deep cycle) adds 150 pounds, safety equipment (including anchor and rope) adds another 100 pounds, 30 gallons of fresh water adds 240 pounds, fishing gear (including cast nets) adds 200 pounds, a couple of coolers with ice, food, and drinks would add 100 pounds, ice for the fish box would add about 100 -150 pounds, and finally add roughly 100 pounds for general accessories and miscellaneous items.  Suddenly your 4,000-pound boat weighs somewhere between 6,500 and 7,500 pounds.  This requires a stout trailer and when you add another 1,000 to 1,300 pounds for the trailer’s weight, this is at the upper end of the towing capacity of most 1/2 ton trucks and SUVs.

Fishermen who tow their boats often and for longer distances would be wise to consider a trailer that well exceeds their anticipated weight requirements.  This can be a trip saver if a stretch of bad road or rough road undergoing maintenance is encountered.  A fisherman, who regularly trailers his boat between N.C. and Louisiana said you will never regret having the extra strength and the upgrade from a 7,400-pound trailer to a 8,600 pound trailer is only a couple hundred dollars.   When making the decision on a $60,000 to $100,000 purchase, that could be the easiest upgrade to justify.

Once you have the correct trailer for your boat, it is time to adjust it to fit.  Some trailer manufacturers have the specs for many boats and can deliver an ordered trailer adjusted really close.  If the boat and trailer are purchased as a package, the dealer should be sure the trailer is adjusted properly.  However, there can be weight and weight distribution differences with different engine and fuel capacity packages, so it’s always wise to check before heading out on the road.  You’ll be the person stuck on the side of the road if something isn’t right, so the time spent checking and fine-tuning the trailer adjustments in your yard is time well spent.

Since you already made sure to have a trailer with adequate weight capacity, you’ll be setting the tongue weight, bunk support, and setting the hitch ball so the trailer is level.  Begin by loading the boat with the heaviest load you will be towing and filling the tires to their recommended inflation.  Tire manufacturers rate trailer tires much like light truck tires.  There are several load ranges.  Sometimes a load to tire inflation chart is included in the owners packet, but they are available online.  Correct tire inflation is critical for proper cooling and sidewall flex.

Tongue weight, which is the amount of weight on the coupler with the trailer level, is set first.  Your hitch, tow vehicle owner’s manual and trailer owner’s manual will list their recommendations for the maximum tongue weight.  These will not necessarily be the same.  The ideal tongue weight will be approximately the midpoint of where all the recommendations overlap.  This is typically somewhere between 3 and 7 percent of the total combined weight of the boat and trailer and should not exceed 10 percent.  For smaller boats, weighing the tongue on bathroom scales will work for setting the tongue weight.

Going back to our earlier example of total weight and rounding to 8,000 pounds to make the math easy, 400 pounds of tongue weight would be 5 percent.  When moving the boat fore or aft on the trailer to adjust the tongue weight, only move the boat an inch or two at a time as this can make a big difference.

Once the tongue weight is set, adjust the bunks or rollers so they offer the most support.  Always check the owner’s manual for recommended locations and note that boats with stepped or ventilated bottoms will have specific instructions for locating the trailer bunks.  For general trailer setup, positioning the outside bunks or rollers under the flat spot of the outside lifting stakes gives the best side-to-side balance and support.  Ideally the bunks or farthest back rollers will be within an inch or so of the transom.

The most often overlooked part of setting up a trailer is getting it level behind the tow vehicle.  This can be fudged a little with single axle trailers but is very important with multiple axle trailers, especially those with torsion axles.  The tongue weight is set with the trailer level and the trailer ball height must be set so the trailer tows level.

Check that the trailer is level, by connecting it to the tow vehicle and parking them on level ground.  Measure the distance from the frame rails to the ground at both ends of the trailer.  If the trailer tongue is high, adjust the ball mount insert down or switch to a ball mount insert with more drop and a lower ball position.  If the trailer tongue is low, adjust or change the ball mount insert so the ball is higher.  The axle(s) create a pivot point, so raising or lowering the trailer tongue will produce the opposite change on the rear.  Make any changes in small increments.

This balance is far more important that most people realize, especially on torsion axle trailers.  It affects the weight distribution and can cause premature wear and failure on axles, hubs, springs and other parts of the trailer.  A high trailer tongue takes weight off the front axle and tires and places more on the rear, while a low trailer tongue reduces the weight on the rear axle and tires shifts more weight to the front axle and tires.

When a trailer won’t balance perfectly, a slight tongue high attitude is preferred to a tongue low attitude.  This is even more critical with torsion axle trailers as they are independent suspension for each wheel.  Extreme out of balance attitudes can cause premature tire, spring, bearing and brake wear, even to the point of failure.

Always secure the boat to the trailer with tie downs.  The stern should be secured with a transom strap that goes all the way across the transom or with individual straps at the corners.  The boat is secured forward with the winch strap or cable and should also be secured down to the trailer with a tie down or bow stay.  This not only secures the boat to the trailer, but helps with the rigidity of the trailer and helps smooth the trailer’s ride.

Once your trailer is set up correctly, develop a plan for periodic preventive maintenance.  Road King, and many other trailer manufacturers, include a checklist for periodic checks and maintenance.

Each time you use the trailer, check the torque on the lug nuts for each wheel, check the lights, brakes and conventional springs and also check that the tires are wearing evenly and are properly inflated.  Owens said all of this is important, but the one thing boaters using trailers constantly overlook is having their tires properly inflated.  He cautioned that this is critical and should be checked every time the trailer is moved.

After launching or retrieving your boat, always rinse the trailer springs, hubs, axles and brakes with fresh water and flush the brake system.  This is especially important for trailers used in brackish and salt water.

Every several months or several thousand miles of towing, check and tighten every nut, bolt, and screw on the trailer.  Also check the brakes for wear, correct operation and correct brake fluid level.  This is also a good time to check all lights and connections to be sure they are working, sealed and clear of corrosion.  Lights are a weak point on many trailers and sometimes stop working when just a little preventive maintenance would keep them going.

The right trailer adjusted properly is a big key to easy and incident free towing.  The other part of the equation is towing with the right vehicle.  Just because a vehicle has a trailer hitch doesn’t mean that it’s meant for heavy or extended towing.  There are variations in towing packages that range from an aftermarket, bolt on trailer hitch to a package with a larger engine, lower ratio rear end, a transmission with a tow/haul mode, an auxiliary oil cooler, an auxiliary transmission cooler, stiffer shocks and springs, larger brakes, a heavier trailer wiring harness and more.

Having all the heavy duty towing options isn’t as important when only towing a small Jon boat a few miles, but when hooked up to a 35 foot, trip or quad engine center console they are all needed and must be working properly.

Owens said one of the things many people overlook when adding up their towing weight is the weight of the trailer itself.  With small trailers and light loads this isn’t extremely critical, but when the trailer weight exceeds 1,000 pounds it is significant.  Trailers are rated at total capacity and load carrying capacity.  The difference is the weight of the trailer.  A towing information booklet that was prepared for Ford is available at Road King Trailer dealers and online.  Owens said that while some of the specifics in this booklet are for Ford products, the general information is excellent regardless of the tow vehicle or trailer brand.

The total weight (boat and trailer) is important with the towing vehicle also.  The actual weight of a boat and trailer combination can be found by weighing them on the scales at a truck stop and some agricultural supply stores.  Towing vehicle capacities are rated with combined gross weight, which also includes the weight of the tow vehicle.  The folks at Doug Henry Chevy, Buick, GMC said there were charts available to show which equipment packages were optimal for towing which combined weight.  The same truck or SUV might tow heavier loads, but it will need a larger engine and/or a higher rear axle ratio.

If you have owned your vehicle for a while and don’t remember what your towing package includes, your dealer can determine the package and get a list of the equipment by checking the Vehicle Identification Number (VIN) on his service computer.  Vehicle manufacturers also have on line and trailering guide booklets, which list the various equipment packages and their capabilities.

The air pressure in the towing vehicle’s tires is also important.  Some of the load will transfer to the tow vehicle through the hitch.  Tires have a recommended tire pressure operating range for different loads and the correct vehicle tire pressure for towing is typically at the upper end of the range.  This is usually more than for non-towing driving and should be adjusted accordingly for each purpose.

The benefits of having a trailer matched and adjusted for your boat, having it maintained properly and having a properly set up, serviced and equipped tow vehicle begin with trouble-free trailering.  It is amazing just how quickly the little bit of extra money or the extra time to make sure everything was right becomes something you should have spent or done when you are broken down on the side of the road.

NOTE:  This information is for pull behind trailers.  As trailerable boat have gotten larger and heavier, some trailer manufacturers are developing fifth wheel and gooseneck style trailers to shift more weight to the towing vehicle, while increasing stability and maneuvering.  These are special trailer setups and the recommendations of the trailer manufacturer and the vehicle towing guide should be followed.

Another things that is beginning to be seen more with towing larger boats is using load distributing hitches, with stabilizer bars.  This hitch system helps maintain the vehicle and trailer level for towing and spreads tongue weight across all of the towing vehicle.  Load distributing hitches have been standard on campers for years and add rigidity and stability to the towing connection.

NOTE:  Boaters and fishermen should be aware that trailering laws differ from state to state.  The maximum width of standard loads are one of the primary differences and the maximum boat width allowed without permits and special markings have been issues at times.  It is a must to know the regulations in your home state and would be wise to check the regulations of any state you may visit or trailer through on a trip.  These are usually online and easily accessed through each states Department of Motor Vehicles or Department of Transportation.