Complete Trailering Guide
The Trailer, Capacity, Brakes and more. Get it all in this complete trailering how-to checklist.
June 1, 2003
The Trailer
Obviously, you can't trailer without a trailer. But you shouldn't trailer with just any
trailer, either. There are three primary types of boat trailers. Bunk trailers, which use bunks (or
rails), are either wood or metal and almost always covered to protect the hull and allow the boat
to slide easily on and off the trailer. Roller trailers use lineups of V-shaped, rubber or
polyurethane rollers to support the boat. Combination trailers use rollers as keel supports
(directly beneath the center of the hull, bearing virtually all the boat's weight) and bunks to
keep the boat from rocking during transport. Some manufacturers recommend one type over the others,
but as a general rule the combination trailer, where the boat's keel supports almost the entire
weight on V-shaped rollers, is the sturdiest and safest for most hulls. Naturally, these are
usually the most expensive trailers, but the added cost is worth it for ease of launching and
retrieving, as well as ensuring safety for the hull and boat during transport.
TIP: Defer to your boat's manufacturer when it comes to choosing a trailer style.
Capacity
The trailer has to be able to carry the total weight of your boat, motor, fuel, water and
all gear. Each and every trailer has, by law, a capacity plate listing the trailer's Gross Vehicle
Weight Rating (GVWR), the maximum trailering weight, and Gross Axle Weight Rating (GAWR), which
gives the minimum tire rating for that load and must be at least equal to the GVWR. To figure your
boat's weight, take the dry weight (look it up in your owner's manual or call your local dealer),
add the maximum fuel weight (fuel capacity in gallons multiplied by 6.5), the maximum water weight
(water capacity multiplied by 8.33) and 100 pounds for gear (ice chests, etc.). For example, if
your boat has a dry weight of 3,000 pounds, a 40-gallon fuel tank and a 20-gallon freshwater
capacity, the weight calculation would look like this: 3,000 + 260 (40 x 6.5) + 166.6 (20 x 8.33) +
100 = 3,526.6 pounds.
TIP: For safety, it's highly recommended that you NEVER exceed 85 percent of the
trailer's GVWR. So for the sample boat with a maximum weight of 3,526 pounds, you'd need a trailer
with a GVWR of 4,150 pounds for safe towing (85 percent of 4,150 equals 3,527.5 pounds).
Brakes
If you're towing more than 1,500 pounds, your trailer should have brakes. Since most boats
weigh more than 1,500 pounds, especially when loaded with fuel, water and gear, most boats trailers
have brakes. Whether the brakes are drum or disk is a separate matter, but both work. However,
because your trailer brakes operate in a difficult environment, spending time completely submerged
when launching and retrieving (possibly in saltwater) and a lot of time sitting unused, they're
extra-prone to rust and corrosion and should be checked at the beginning of every season and at
least bimonthly during the season for safety. Also, be prepared to shell out some cash for the best
brakes possible. To handle submersion, good trailer brakes have stainless-steel and aluminum
components, and are much more expensive than the brakes on your car or truck. But when you're
trying to slow down on a steep hill, you'll be glad you paid the extra money.
Most trailer brakes are either surge-actuated or electrically actuated. Both systems work,
but many prefer electrically actuated brakes because these read and amplify your input from the
brake pedal, so you get predictable braking regardless of slope, speed or direction. Surge-actuated
brakes, on the other hand, use a moveable joint at the trailer/vehicle connection that determines
if the trailer is "gaining" on the tow vehicle; if so, the trailer brakes kick in. The problem is,
sometimes you want a little extra braking help when backing down a steep ramp, and surge-actuated
brakes won't be there since the joint sees the trailer as "falling behind" the tow vehicle and
therefore in no need of braking. It's worth noting, though, that if you submerge electrically
actuated brakes that aren't properly sealed, they short out and quit working, so neither system is
perfect.
TIP: If you're extremely thorough about maintenance, electrically actuated brakes
are a good choice, but if you let maintenance slide at all opt for surge-actuated brakes on your
trailer.
Tongue Weight
Tongue weight is the amount of pressure applied to the trailer hitch by the trailer tongue,
and it plays a large role in how well the trailer handles on the road. Optimally, tongue weight
should be 5 to 10 percent of total trailer weight. Too much weight on the tongue will cause the tow
vehicle to sag at the rear and can cause enough lift at the front end of the tow vehicle to
compromise steering. Too little weight on the tongue can cause the trailer to fishtail at highway
speeds, an incredibly dangerous situation. Adjusting the tongue weight isn't simply a matter of
moving the boat toward or away from the tongue. Many higher-quality trailers have adjustable axles
so you can adjust the trailer's pivot point, thereby safely adjusting the tongue weight. Obviously,
this can be a pain if you don't have some pretty specialized equipment, so it's usually a job best
left to a dealership.
TIP: Even when buying a boat/trailer combo package, make sure the dealership
properly adjusts the tongue weight before taking delivery.
Hitch
When it comes to getting hitched, you have a choice. There are three classes of hitches that
essentially match up with the three basic sizes of hitch balls: Class I (1-7/8 inch ball), for
loads up to 2,000 pounds; Class II (2-inch ball) for loads up to 3,500 pounds; and Class III
(2-5/16 inch ball) for loads up to 10,000 pounds. (A Class II hitch can be used with loads up to
6,000 pounds if heavy-duty balls with large shanks are used.) The classification is determined by
the trailer tongue - a Class I trailer will only work with a Class I ball, for example - as well as
the tow vehicle's towing package. A tow vehicle with a Class I towing package will never
accommodate a Class III trailer and load. A tow vehicle with a Class III towing package, however,
can have a Class I ball installed and work very nicely with a Class I trailer. The hitch receiver
is usually mounted directly to the chassis for strength, so it's a job for a professional.
TIP: A limited-pivot, shock-absorbing drawbar will make connecting the trailer to
the tow vehicle much easier as well as providing a much smoother, more comfortable ride.
Tires
Too many people think that since they don't use a trailer too often they don't have to worry
too much about the tires. That's about as wrong as it gets. Like the brakes, the tires live in a
difficult environment and are prone to drying and cracking as well as developing "flat spots" as a
result of sitting in one position for extended periods. The fact is, a trailer on a trailer tire
can be one of the more dangerous on-road situations you'll ever encounter, so it's more than worth
taking a little extra precaution when it comes to the rubber that meets the road.
Size
Let's make this clear: It's important that all the trailer's tires be the same size. Beyond
that, the rule of thumb is the bigger the better when it comes to tires and wheels. It's a matter
of physics. If, for example, your speedometer is reading 70 mph and there are 16-inch wheels on
your tow vehicle, the 12-inch wheels on your trailer are spinning at 90 mph, which generates more
heat, more wear and more danger. Of course, there are limits. If you want to tow a smaller trailer
- for a PWC, for instance - it's not practical to say the trailer tires should be as large as the
tow vehicle's. Also, it's important to make sure that both (or all four) trailer tires are either
radial or bias-ply - mixing can cause problems.
Load capacity is another factor to consider. On a single-axle trailer, each wheel will be
supporting approximately half the total trailer weight; on a tandem-axle trailer, each wheel
supports about a quarter of the total weight. (The trailer hitch supports less than 10 percent, so
don't factor that in.) This means you need to read the tires' load capacities and make sure they
can handle the weight safely. The load rating is molded into the sidewall, usually in both pounds
and kilograms.
TIP: Don't buy "trailer-only" tires with the warning "Not For Passenger Vehicle
Use," even if you're using them on a trailer. These tires do not meet U.S. Department of
Transportation standards. Passenger-grade tires may cost a few bucks more, but they're worth it.
Inflation
Under-inflated tires are arguably the single most prevalent cause of problems for both tow
vehicles and trailers. They can cause rough rides, blowouts, early wear and replacement, and a host
of other easily avoided hassles. Trailer tires are especially apt to be under inflated since they
often sit unused. The solution? Go to the local auto parts store and buy a tire gauge -
pencil-style analog gauges are less than $5 and high-quality digital gauges are less than $20 - and
use it every time you trailer. It takes 30 seconds to check the pressure in four tires and maybe
three minutes to inflate them properly at the service station down the street. This is far and away
the easiest preventative measure you can take, and it even improves your fuel economy.
TIP: Check the inflation of your tow vehicle's tires while you're at it.
Tow Vehicle
As critical as the trailer is to a good towing experience, the tow vehicle is an equal
partner. Back in the days of giant cars with chrome bumpers the size of New Hampshire, the family
station wagon could be pressed into service as a tow vehicle and do a pretty good job. Today,
though, few passenger cars are designed to handle the loads and stresses of towing boats, so the
most popular options are SUVs and pickups. Each has its pros and cons, but both SUVs and pickups
work well as tow vehicles, as long as they've been properly equipped.
Weight Rating/Capacity
Just like the trailer, your tow vehicle has a GVWR, although in the case of the tow vehicle
that refers to how much stuff you can actually put IN the truck. The more important rating is the
Gross Combined Weight Rating (GCWR), which includes the weight of the truck, the trailer and the
load. Most manufacturers, however, also give towing capacities for their vehicles. The choice of
engine, the drivetrain and towing package play a role in the GCWR. For example, a 2003 Ford
Explorer with a 4.0L V8 engine, 2-wheel drive and a standard Class II towing package has a listed
towing capacity of 3,280 pounds, while an ‘03 Explorer with a 4.6L V8, all-wheel drive and a Class
III towing package has a 7,000-pound capac-ity. While there's not much you can do about the engine
and drivetrain on a tow vehicle you already own, you can upgrade the towing class to accommodate a
larger boat/trailer combo.
Mirrors
Over the past few years, most truck builders have started offering extended, oversized side
mirrors designed especially for towing. If you're in the market for a new tow vehicle, these
towing/camping mirrors are a must. The best of them even have separate convex mirrors for added
visibility and safety. If you already have a tow vehicle and it's equipped with the standard,
smallish side mirrors, don't worry - just head over to the local auto parts shop and pick up either
a set of oversized side mirrors (the best plan), or at least some stick-on convex mirror enhancers.
You need the improved mirrors because towing presents some visual obstacles. First, the main
rearview mirror, the one on the windshield, is rendered useless. Second, small side mirrors are
okay for checking your blind spot when you're not towing, but with a trailer behind you, your field
of vision needs to include the trailer and what's behind it, as well as what's right next to you.
And oversized mirrors, preferably with a convex section, are the only way to get the field of
vision you need for safe towing.
Lights
A trailer without functioning running lights, brake lights and turn signals is an accident
waiting to happen. Installing a plug-in trailer light converter is an easy job, and many trucks
with towing packages have converters installed before delivery. It's possible, however, that your
tow vehicle's wiring isn't up to the drain of trailer lights, in which case you'll need to install
a heavy-duty wire and converter directly from the battery to the trailer, working in tandem with
the tow vehicle's lighting to illuminate properly. As a result of frequent submersion, trailer
light bulbs have a tendency to be unexpectedly short-lived, so it's very important, both for safety
and for avoiding traffic tickets, to plug in the trailer lights and make sure they're working
properly. Check the running lights when the tow vehicle's headlights are on (you should leave your
headlights on at all times when towing, even during bright summer days), brake lights when brakes
are applied, and turn signal flashing. If there's a problem, fix it. And do this every time you
leave the house and every time you leave the launch ramp.
TIP: Keep a full set of spare trailer light bulbs in your tow vehicle.
Towing
You have a tow vehicle, a trailer and a boat, so it's time to hit the road. Before you go,
though, make sure you drain the boat's bilge (it's a good idea to remove the drain plug, but
remember to replace it before you launch!), attach safety chains from the trailer to the tow
vehicle and secure the boat to the trailer with tie-downs. If your boat has a Bimini top or any
other canvas, remember to remove or lower and secure it, and to stow and secure any gear inside the
boat so it doesn't come flying out on the highway.
TIP: If you put a half-twist in the tie-downs, it will dramatically reduce
oscillation and vibration due to wind.
Driving
If your tow vehicle has an automatic transmission with a "Tow/Haul" or "Overdrive Off"
setting, use it. This will adjust the transmission for better performance in the low-gear range
where you need added torque and rpm. Also, if you have an on-demand four-wheel drive, be sure you
set the drive to "two-wheel" or "two-wheel high." Four-wheel drive is only needed if there's a
problem with traction, such as on a slippery or gravelly launch ramp, and as a general rule you
should never drive faster than 20 mph with the four-wheel drive engaged. If you have full-time
four-wheel drive, or all-wheel drive, don't worry - the tow vehicle's onboard computer will make
the appropriate adjustments.
There's one prime rule for towing: DON'T RUSH. Because of the added load, you'll take longer
to accelerate and significantly longer to slow down than when you're not towing, so leave at least
three times more space between you and the vehicle in front of you than you normally would. The
lack of acceleration will make passing all but impossible, so get in the right-hand lane (on
multilane roadways) and stay there. The objective is to reach the launch ramp or to get back home
safely, not to get there quickly. Also, a simple thing like making a right turn can take much more
space than you may expect, so always leave yourself a very wide berth.
When descending a hill, don't ride the brakes. Tap the brakes intermittently to scrub off
speed without overheating and compromising the brakes' ability. If it's a particularly long or
steep hill, shift the transmission into a lower gear and let the engine assist in braking.
Should something go awry, don't panic. Take your foot off the gas pedal and begin braking
gradually. Jamming the brakes will only make matters worse.
For most people, reversing is the most troublesome aspect of towing. A few tricks of the
trade, however, make reversing a snap. First, slow down. Way down. Idle speed is as fast as you
should ever go. Second, have an observer stand behind the trailer, on the driver's side, to help
guide. Third, give yourself as much room as possible; there's no reason to make this any more
difficult than necessary. Fourth, make the smallest possible moves. Finally, put your hands at the
BOTTOM of the steering wheel and move your hands in the direction you want the trailer to go. If
the trailer needs to go to the right, move your hands right. If you're holding the bottom of the
steering wheel, this will actually turn the wheel LEFT and the trailer will back to the right. It's
counterintuitive, but it works.
TIP: Practice backing and turning with an empty trailer (if possible) in an empty
parking lot to hone your skills before going to the launch ramp.
Launching
The typical overcrowded launch ramp on Saturday morning can be intimidating to novices who
aren't completely comfortable with towing and reversing. Don't worry. The key is to be prepared and
take your time. Nobody minds if you take a while and launch correctly; you'll be thrown to the
wolves if you get in a rush and wind up needing a half-dozen tries to actually get the boat in the
water. Here are the steps to perfect launching:
AT THE RAMP
> Give yourself as much room as possible to maneuver.
> Maneuver in the smallest increments possible.
> Go slowly.
> Back down the ramp until the tow vehicle's wheels reach the water but are not
submerged.
> Set the parking and emergency brakes and block the wheels.
> Have someone get in the boat, run the blower and start the engine.
> Loosen the bow-eye strap, then release it.
> The boat should slide back off the trailer with a strong push or a little
reverse throttle - but leave the engine/outdrive trimmed up as far as possible.
> Pull the boat away from the ramp.
> Remove the wheel blocks, start the engine and pull away from the ramp.
> Secure the tow vehicle and trailer in the parking lot.
> Pick up all passengers away from the ramp if possible.
Retrieving
Getting back out of the water is where most people run into trouble because they're tired
from a day on the water and in a rush to get out and get home. Don't make that mistake. Take your
time and retrieve safely, following these steps:
> Everyone should exit the boat except one person to drive it onto the trailer.
Offload away from the ramp if possible.
> Back the trailer down the ramp until the tow vehicle's rear wheels reach the
water.
> Set the parking and emergency brakes and block the tires.
> Trim the engine/outdrive all the way up and pull the boat SLOWLY onto the
submerged trailer. Don't try and power the boat onto the trailer - that's a good way to wind up
with a boat in the bed of your pickup. As soon as possible, attach the winch line and turn off the
boat's motor.
> Using the winch line, winch the boat onto the trailer.
> Remove the wheel blocks and pull the boat and trailer away from the ramp.
> Do cleanup, reloading, stowing, securing and safety check in the parking lot,
away from the ramp.
> Attach tiedowns, trailer light wiring and safety chains, and remove the
boat's drain plug before leaving the parking lot.
Storage
Whether it's over the winter or just for the week, you have to store your boat and trailer
when you're not using them. Sadly, it's not as simple as backing it into the driveway and unhooking
it, unless you like the idea of someone driving off with your boat and motor. The best place to
store your boat and trailer, even for a short period, is in a covered, locked area such as your
garage or a self-storage unit that allows boats and trailers (many do, especially near bodies of
water). Even if you have an enclosed, locking site for storage, it's a good idea to invest in a
trailer lock, which prevents anyone from putting the trailer on their hitch and driving off. These
are very inexpensive and found in auto parts shops everywhere. It's also a good idea to etch some
identification onto the trailer and the boat, just in case.
If you don't have an enclosed, locking storage site, park your trailer near an immovable
object like a tree or a post you've cemented into the ground and chain the trailer to that object.
If you're storing the trailer for a short period - say, a week or two - don't worry about
putting it on blocks. But if it's going to be stored for a while, more than a couple of weeks, get
a set of jack stands (available at your local auto parts store) and raise the trailer onto the
stands to relieve the pressure on the suspension and tires. This will extend the life of the
suspension and help prevent "flat spots" on your tires due to long-term storage. If you're not
using stands, block the wheels; if the boat's going to be stored for a while go out and move it so
the wheels rotate a quarter-turn or so every week or two. Remove the boat's drain plug and raise
the trailer tongue a few inches so the boat tilts back slightly and any accumu-lated water can
drain out. Loosen the tiedowns and winch line. Cover the boat with a tarp to protect it from the
weather, but cover it loosely enough to allow air to circulate to keep mold and mildew to a
minimum.
TIP: Before storing for the winter, check your boat and trailer registration and
license tags and renew them if they'll come due before the next season.