Those of you who regularly pull a boat or travel trailer probably already know about all you need to know about towing. But for those who are new to towing or who only tow boats or trailers occasionally, you might find some value in the tips in this post.
First of all, proper preparation of both the towing vehicle and the towed vehicle is critical. Towing puts an extra load on just about all parts of the vehicle doing the towing: engine, transmission, differential, brakes, cooling system and even the suspension and the frame. ALWAYS be sure the vehicle and the hitch are rated to tow the weight being towed. I have seen the results of attempting to tow a trailer larger than the towing vehicle is rated to handle. They range from overheated engines and transmissions to spectacular accidents that totally destroyed both tow vehicle and trailer. I saw a half-ton pickup towing a 28' travel trailer flipped by high winds like it was light as cardboard. You've all likely seen overheated vehicles pulled over on long grades, often the result of overloading. Overloading will significantly increase fuel consumption and create very real safety hazards, especially when negotiating mountain roads. Make sure all the tires on all vehicles are properly inflated and have a safe amount of tread. Verify engine oil, transmission fluid, and coolant levels on the tow vehicle. Know the condition of the brakes and wheel bearings and tires on the trailer. Make certain the hitch you are using is rated to handle the load you'll be towing. Hitch pins typically come in both 1/2" and 5/8" diameters. Using a 1/2" hitch pin in a hitch with a 5/8" hole will result in unwanted movement and clunking of the hitch, possibly creating excess wear that may cause a premature failure. Secure all loads (inside and out) so they won't be blown around at highway speeds or tossed around during changes in speed or direction.
Towing means you will need to make adjustments to your normal driving patterns. First of all, you combined vehicle length and weight will be greater than you are used to and you need to compensate, slowing down earlier, giving yourself more room for accelerating, turning, lane changes, and stopping.
You also need to pay attention to what you are towing while you are towing. Frequently check your rear view mirrors or backup camera. A significant change in the angle may indicate a flat tire. Flat tires may also cause smoking and the a rumbling feeling transmitted through the hitch. If you suspect a flat tire, slow down and find a safe place to pull over as soon as possible. Better safe than sorry. If you don't find anything wrong, you will have only lost a few minutes, but if you fail to pull over you will greatly magnify the potential damage. Left unattended, a flat tire can cause significant damage to a trailer and perhaps to other vehicles following or passing you. One careless driver started wildfires all across Idaho and Washington because he continued to drive with a burning tire!
Avoid sway. Swaying can be caused by a number of things. Wind often plays a significant part as do gust from passing trucks. An anti-sway bar help reduce sway. It consists of a friction bar between the hitch and the trailer tongue that dampens sway. Having too little weight on the tongue can increase the risk of sway. Make sure the weight on your trailer is properly distributed. Boats with outboard motors hanging off the back shift a lot of weight off the tongue so removing the motor and carrying it in the tow vehicle or in the cockpit of the boat will help with weight distribution. Our sailboat started swaying really badly on the way to the lake just 1 mile from home. One of the wooden bunk boards that supported the boat had broken, letting boat fall down onto the fender, pushing it into the tire and creating significant drag on that side. If your trailer starts to sway, slow down until it stabilizes. Pull over if you can find a safe place to do so. Try to determine what triggered it to start swaying. Things to consider: over steering, wind gusts, un-level roads, poorly distributed weight. There isn't much you can do about roads or winds except slow down so they have less effect but if you caused the problem by over-correcting or changing lanes too quickly, learn your lesson and make always small, smooth, slow changes. If weight distribution appears to be a factor, shift some of the load to put more weight on the tongue. If you have a sway bar, try tightening it down more to increase the amount of friction inside of it. Anti-sway bars typically have two parts. One slides inside the other. One is hooked to the hitch, the other to the trailer tongue. One of the parts includes a friction material like that used on brakes. There is a lever that adjust the amount of pressure and thus the amount of friction within the sway bar. Note that sway bars on boat trailer might get wet and be less effective until they dry out.
Slow down! The extra weight puts more strain on your tow vehicle and can seriously affect handling. Trailers are more likely to sway or fishtail at higher speeds. Maintaining a slower speed reduces the risk of fishtailing. If you see or feel your trailer start to swerve behind you slow down right away! You may have seen the speed limits U-haul imposes when you rent their trailers. That has come from years of experience and hundreds of thousands of miles of towing. In some states, such as California, vehicles towing trailers are limited to 55 mph, even on freeways with much higher normal speed limits. In addition, slow down right away at the first sign of trouble. If your trailer starts to sway, you feel an unusual vibration, hear strange sounds, or see smoke near the wheels and tires, slow down and pull over and locate and correct the problem before it becomes catastrophic.
State laws governing towing may differ so be sure you understand the limitations before you find yourself getting pulled over. Some states have limitations or restrictions on passengers riding in a travel trailer. Where is allowed it often requires two-way communication such as walkie talkies or some kind of intercom between the trailer and the driver of the tow vehicle. Overall length and weight limits may also vary. Some states prohibit towing more than one trailer while in others it may be permitted. California, for example, prohibits towing more than one trailer but when I moved to Utah it wasn't unusual to see a large pickup pulling a travel trailer pulling a boat.
When is a trailer not a trailer? In California I saw one-wheeled motorcycle trailers being legally pulled behind travel trailers. That is because the one-wheeeled "trailer" was not "articulated", that is, it was connected to the tow vehicle in at least two places, making it an extension of the tow vehicle instead of a trailer.
Trailer licensing varies from state to state also. Some states required license plates on all trailers. Some only required them on trailers over a certain loaded weight. Trailer licenses typically follow the same renewal pattern as motor vehicles, but not always. When I lived in California they introduced a "Perpetual Trailer License" that did not have to be renewed each year. Typically you will be OK if the license status of your trailer is proper for the state of your residence, allowing, for example, an Oregon resident to tow a light weight, unlicensed trailer with his/her Oregon licensed vehicle and driver's license in another state even if that state requires all trailers to be licensed.