How to control sway after it starts?

[CATransplant]

Re: How to control sway after it starts?

Just as an aside here, since the other stuff has been discussed, I think I know why you got the sway on your double tow.

If the tongue weight on the camping trailer was a little light, which is not unusual, since they're usually packed badly, and the tongue weight on the boat was a little heavy, there's your problem.

When you hook up the boat to the back of the first trailer, the tongue weight of the boat levers the trailer's tongue up, lessening its tongue weight. The quickest way to start a sway on a tow is too light a tongue weight. That's multiplied if you have a second trailer tacked on. A very dangerous combination.

Some guys manage a double tow all the time, but it's not an easy thing to do safely. Managing tongue weights is super critical.

 

[cbavier]

Re: How to control sway after it starts?

I agree that the last thing you want to do is hit the brakes. You should alway's speed up untill the trailer straightens up. When it is swaying the boat is pushing you and trying to get you to go faster than you want to go. By speeding up you are going to start pulling the boat again instead of having it try to push you and start swaying.

Best answer and explanation so far. By speeding up you are going to start pulling the boat again instead of having it try to push you and start swaying.[/QUOTE]

 

[ebry710]

Re: How to control sway after it starts?

If your trailers are out of balance, speeding up may not straighten anything. I would call the manufacturer of the pull trailer and ask what their opinion is. Just because its legal and there is a hitch welded to the back of the trailer doesn't mean its a big rig. Oscillation is a matter of speed vs sway. Just like a tire out of balance, speed doesn't always stop the wobble.

 

[sharps45]

Re: How to control sway after it starts?

I consulted an 'expert' on this matter, a former teamster, truck driver, mechanic, all around knowledgeable guy. He explained to me the geometry of trailers and towing, from tongue weight to toe settings to level of tongues.
His thoughts are that the level of the towing vehicle to the hitch height is the number one desirable thing for towing safely. You want either level or slightly downward. You want the tires on the trailer to be in a 'following' stance- the centerline of the tire balance being on a straight vertical axis or slightly rearward- so the tire pulls not pushes. A tongue height upward tends to put the balance forward, pushing the tire. This gives the trailer more ability to go where it wants- not a desireable thing, especially with a single axle trailer. The toe settings on the axle is next important. The tires should angle slightly inward- 2-3 degrees- on an unloaded trailer, so that when the trailer is loaded they pull outward into a straight line. This can be measured with a string pulled between the front of the tires vs the rear of the tires, or just using a tape measure. An outward toe is not desireable, as the trailer will want to go where the tires point. Double axles are easiest to check by stringing your string around all four tires in a loop, and checking if the string touches the tire sidewalls equallyand eyeballing the string for angles off the sidewalls. You can also see if you have a problem by tire wear- worn more inside to outside suggests a toe out condition and vice-versa. (I checked the boat trailer I towed and the tires were badly worn in this pattern). Also, the trailer comes from the factory with the installed wheels and tires matched for the geometry of the trailer. Changind out these things can change the trailer pulling characteristics, especially if you put on wider tires or rims, and many dealers are unaware of this. Of course the way the trailer is loaded weight-wise will change the hitch-tongue angle and thus the tongue weight.
He also agreed that speeding up is the best way to get a sway under control.
Anyway, I've learned some very valuable things from this discussion, and if i ever decide to tow tandem again I will do some jockeying with tongue levels and weights before I agree to do so.

 

[id30066]

Re: How to control sway after it starts?

Well, I know from 15 years of being in the rv'ing business that whenever I am pulling a trailer, not 5th wheel, that if I get sway I gently apply the brake control to straighten the situation out. It has worked on everything from 18ft to a 40ft park model. I have towed so much that I dont use weight distributing hitches anymore. I have never towed tandem, its against the law in Oregon, so I cant help with that situation. Just my 2 cents.

 

[reelfishin]

Re: How to control sway after it starts?

It sounds to me like he may have had brakes on the first trailer but not likely on the second one?
If that's the case, applying the trailer brakes may have little if any effect on the second trailer.

Hard or sudden acceleration can and most often will stop a trailer from swaying but only if you have the tow vehicle power to do so, and the immediate step after both are back in line IS to slow back down to a speed which does not induce sway.

There may also be other factors at work here other than just trailer angle, or at least induced or aggravated by the angle. If towing a large RV, there will also be lots of strong turbulence behind that trailer and a certain amount of draft effect, which can create downward force to the rear of the boat, thus in effect lightening the tongue making it even more unstable.
I ran into this pulling a double in which the first trailer was a large enclosed trailer, and the second a dump trailer. The situation was improved by adding forward weight and covering the dump trailer with a tarp.
A boat hull also can act as a reverse wing at higher speeds, creating lift under the boat. A front high trailer with the added weight of air pressure coming off the roof of the RV hitting the boat behind the axle or against the transom adds to this problem.

I have a light home made utility trailer made from an old pop up camper frame, I used it for years for carrying ATVs.
It's got 12" tires and is about 100" wide by about 10' long with a 60/40 balance. It tows great and is perfect for the task it was designed for, but the solid floor can catch wind if the tongue is not level. I towed it the length of the PA turnpike a few years back after returning from Ohio to help a buddy move with it, I returned in a different truck then I drove out, the new truck was not a good match and the tongue was about 6" too high. At about 65mph, the trailer would get airborne, it would touch down again with a loud tire screech which sounding like an airplane touching down at about 60mph. The good part was that it created little to no drag when it lifted off, but it would sway and nearly contact the guard rails or cars in the other lane on curves. It still has brush marks on the corner posts where it rubbed a few guard rails. When we first left with that trailer, my concerns were wheel bearing or tire failure do to heat since they were so small, but the wheel bearings weren't doing much work on the return ride.

 

[ebry710]

Re: How to control sway after it starts?

I consulted an 'expert' on this matter, a former teamster, truck driver, mechanic, all around knowledgeable guy. He explained to me the geometry of trailers and towing, from tongue weight to toe settings to level of tongues.
His thoughts are that the level of the towing vehicle ...........

Pretty awesome information. Bottom line sounds like: tow tandem without knowing your trailers is tricky

 

[old-gubbins]

Re: How to control sway after it starts?

Re; Titanium:
"The NHTSA, among others. "If you have an electric trailer brake controller and excessive sway occurs, activate the trailer brake controller by hand. Do not attempt to control trailer sway by applying the tow vehicle brakes; this will generally make the sway worse."
Reference: http://www.nhtsa.dot.gov/cars/proble...ing/Towing.pdf
The idea is to re-establish tension between the tow vehicle and the trailer to damp the sideways oscillation. You can do that by accelerating the tow vehicle or braking the trailer. Both work, but trailer braking gets you to a slower, safer speed faster."

I accept this is right when dealing with ONE trailer, but would only hold true with TWO trailers if you were braking the SECOND trailer, not the first one!

o-g

 

[Titanium48]

Re: How to control sway after it starts?

^^^ True, although I suspect it would still work if the lead trailer is the unstable one and the second trailer is significantly lighter and not able to push the lead trailer around once it is stabilized.

 

[Titanium48]

Re: How to control sway after it starts?

I have a light home made utility trailer made from an old pop up camper frame, I used it for years for carrying ATVs.
It's got 12" tires and is about 100" wide by about 10' long with a 60/40 balance. It tows great and is perfect for the task it was designed for, but the solid floor can catch wind if the tongue is not level. I towed it the length of the PA turnpike a few years back after returning from Ohio to help a buddy move with it, I returned in a different truck then I drove out, the new truck was not a good match and the tongue was about 6" too high. At about 65mph, the trailer would get airborne, it would touch down again with a loud tire screech which sounding like an airplane touching down at about 60mph.

I have a slightly smaller one (80 inch wide, 8 inch wheels) with the same problem but in reverse. The hitch on my Saturn puts the tongue a little low and it hits an aerodynamic wall at about 100-110 km/h. Won't go any faster and uses twice as much fuel as usual. I need to find a new ballmount with more rise, but 1 1/4 in ballmounts seem to be a bit hard to find.

 

[erikgreen]

Re: How to control sway after it starts?

If the sway is caused by wind or the geometry of the trailers, you will need a different solution than if the sway is caused by an improperly loaded trailer.

Last summer my lack of tongue weight caused my trailer to sway hard enough to break the bead on my truck's rear tires... by the time I noticed it, it was too late to do anything at all except crash....

Never again will I drive without enough tongue weight, and I will always make sure the boat is strapped down, the trailer brakes work, and I have a big enough tow vehicle. I will not risk my life for convenience ever again.