MacGregorSailors.com

My two trailering experiences with the 26X/50hp Tohatsu were white knuckle affairs. Before moving the two full nine gallon fuel tanks and gear forward this combination was not safe at even 50 mph. After moving fuel and gear to the v-berth, the trailer would begin swaying and affecting the Safari van at speeds slightly over 60 mph. I found this to be very uncomfortable.

It shouldn't be necessary to have to move tanks forward etc. or fuel up at the destination to be able to safely tow the Mac.

I am considering having my trailer sandblasted and galvanized. This would be a good time to relocate the axle to hopefully eliminate this unsafe condition.

Has anyone done this?

Just a question- did you ensure the boat was fully forward on the trailer? I have noticed that it sways more when not seated fully forward.

Also- not sure how much galvanizing costs, but POR-15 is pretty awesome- the trailer won't rust when this stuff is applied properly. Takes a bit of time, but not too hard to do by yourself and probably a lot cheaper than galvanizing.

Jeff S

My experience was pretty much the same towing with a Ford Explorer. I moved everything I could forward to the v-berth, but rather than put fuel tanks in the cabin, which I think is a really bad idea, I just left them empty until shortly before arrival at destination. It was still marginal.

If you regularly travel with full fuel tanks and a decent complement of cruising gear, you are almost certainly exceeding the 3500 lb limit of the trailer. Just adding the known stuff up, I came up with 4000-4200 lbs for my boat. I elected to go the whole nine yards, moved the orignal axle forward and added a second tandem axle, with four wheel disc brakes. If you're going to dump a ton of money into your trailer anyway, I recommend you consider the second axle. My mod second axle covers it in detail.

If not, moving the single axle rearward should help. Based on the "before" numbers, I calculated the total change I needed to get the tongue weight up to 10% and moved the axle pivot point rearward just over ten inches. I haven't remeasured for the "after" numbers but I believe everything is now pretty much as it should be. If you have actual weights it's not a difficult calculation.

It was sure nice with this boat. All I had to do was to move the post forward to get more tongue weight.

Has anybody tried the anti-sway bar that the R/V's use?

Moe should chime in here, but it is my understanding the anti-sway bars interfere with the brakes on the trailer.

There's no such thing as "eliminating" sway of a towed trailer. For every combination of tow vehicle and trailer there is at least one, and usually more than one, combination of environmental factors that can make it sway. Some, even with inadequate rigs, may go their whole towing life without experiencing sway. Others aren't so lucky. A little sway under normal conditions may scare some into fixing the problem, but others may just try to drive below the sway speed to get by. This is a dangerous situation because they have no margin for safety when the right combination hits. Little sway can escalate into severe sway in just a few oscillations. The larger the margin of safety you have, the less likely it is sway will occur, and the less impact it will have on the rig when it does. Just because you've never experienced sway, doesn't mean your rig is adequate or you're adequately prepared for it.

Certainly, the greater percentage of tongue weight, which is really telling you where the center of mass is with regard to the axle(s), the lower the probability of sway, and the lower the intensity of the sway when it happens. Fifth-wheel and gooseneck trailers have around 20% tongue weight and sway much less often, and much less severely, than behind-the-bumper connected trailers. Behind-the-bumper connected trailers can't tolerate that high of a tongue weight, because it's applied well behind the rear axle, and has leverage to lift weight off the front axle. That can cause understeer, especially on slick pavement. In the RV and utility trailer world, the minimum tongue weight percentage has always been at least 10%, and even a little more, if possible. I've towed for a living and subscribe to this recommendation even for boats, but I see recommendations for boats and boat setups, with much less. That's not for me.

I usually don't see dual axles on the trailer as having much benefit during sway, except in the case where the tire and spring ratings are marginal or inadequate for the load. Unfortunately, that's the case with many, if not most, MacGregors loaded for the weekend. Sway increases the load on these, and marginal components can't resist it.

Fifth-wheels and goosenecks have another advantage during sway. The point of pivot is over the tow vehicle rear axle, and the trailer can sway without yawing the tow vehicle (yaw is rotation of the vehicle around a vertical axis). Sway's side to side forces only try to move the rear axle, and the tires, laterally. Because of the high hitch weight of these trailers, that rear axle is most often a "dually" and has more lateral grip in addition to weight carrying capacity.

With a behind-the-bumper connection, the lateral forces of sway are fed into a lever arm that extends well behind the tow vehicle rear axle. This multiplies the force on the rear axle in the direction of sway, and at the same time applies a force in the opposite direction to the tow vehicle front axle, "yawing" the whole vehicle. As the tow vehicle yaws in one direction, it's storing energy that will be fed back into the trailer tongue on the opposite swing of the trailer sway.

The shorter the wheelbase,
the greater the rear overhang,
the narrower the track,
the taller the height,
the softer riding and/or the more worn out the suspension,
the softer the tires,
the more susceptible the tow vehicle will be to sway and
the more the tow vehicle will contribute to sway when it happens.

In all these respects, the GMC Safari/Chevy Astro says to me, "Let's Rock"... literally.

The short 111" wheelbase doesn't give the vehicle much longitudinal stability, and combined with a 46" rear overhang (probably 50" to the ball center from the rear axle center) gives sway a large leverage to yaw the van. It also gives tongue weight more leverage and limits how much you can increase it without lifting too much weight off the front axle, and altering the steering geometry. By my rule of thumb, a 111" wheelbase is good for towing a 23' long trailer rig, at most, but the large overhang would make me reconsider even that much. I'd prefer at least 130" wheelbase for towing a MacGregor.

The taller height coupled with the slightly narrow track is going to encourage energy storing roll during sway and yaw, meaning the tow vehicle then feeds back that energy on the opposite swing.

The relatively soft suspension and soft passenger car tires are also going to permit more roll, and in addition, store sway energy themselves. If the shocks aren't stiffly valved and in good condition, this can contribute to the problem. So can soft spring and sway bar bushings.

So we've seen that both trailer and tow vehicle can contribute to sway, but there's often another contributer, and that's a driver who tries to compensate for sway by steering. My advice is don't even try. In most cases, you'll be reacting and following, with the end result that your steering adds to it. You'll usually be better off by relaxing, loosening your grip on the wheel slightly, and easing off the throttle, without braking, to slow down. You sure don't want to apply the brakes when the trailer is swung out to one side of the tow vehicle.

As Tom points out, with surge brakes, you can't really use one of those friction sway-dampers common in the RV world, nor can you use an equalizing hitch or anti-sway hitch such as the Dual-Cam, Equal-I-Zer, Pullrite, or Hensley, without impacting braking. You also don't have a manual trailer brake control lever/button to apply the trailer brakes without applying the tow vehicle brakes, which will usually stop a swaying rig. These are certainly nice to have, but they shouldn't be used to fix a sway problem. They should be seen as an extra last resort, even where they are possible.

Yes, you need to get the tongue weight up where it should be. Make sure you do it with the trailer actually loaded as it will be towed, and with the proper drop bar in the hitch receiver that lets the trailer sit level.

But be careful what that does to weight leveraged off the front axle onto the rear. Also be aware that raising a tow vehicle rear end sagging from heavy tongue weight with helper springs, air bags, or air shocks, doesn't fix that problem, but mostly just hides it. While it may correct the steering geometry, it's doing little to solve the weight balance problem. It's essentially just like raising the pivot point of a see-saw. RV hitches can be "weight-distributing" with spring bars that transfer weight back onto the front axle (and a little bit back to the trailer axles in the process).

The right solution here includes getting a tow vehicle with longer wheelbase, relatively shorter rear overhang, stiffer suspension, and stiffer light truck tires instead of smooth riding passenger car tires. However, if you can't do that, you can upgrade the passenger car tires to some light truck ones that you can run 45-50 psi in, replace worn and marginally adequate in the first place factory shocks with stiffer valved performance ones, replace the mushy suspension bushings with polyurethane ones, and if you don't have a rear anti-roll bar from the factory, maybe even add one.

Anyway... hope this helps... it's how I see it.

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Moe

Moe said it about as well as it can be said.

I have towed a 22' two axle trailer loaded to 5000 lb with an equalizer hitch on an Astro, and it was pretty solid. A time or two when going a short distance I left the equalizer bars off, and even with plenty of tongue weight I wasn't too happy with what was left of the handling.

One caution if you decide to upgrade the tires. The original factory wheels may only be rated for the 35 psi passenger car tires. I ran up against this with my Expedition. So you may have to factor in a wheel upgrade along with the tire upgrade. A GM dealer should be able to tell you for sure. Luckily (at least the Astro I had) used the same wheels as the standard GM 1/2 ton pickup, so there are plenty of different styles and sizes available.

I would normally not trust a tire salesman to provide a correct answer to this question. Some are quite knowledgable, but some are incredibly ill informed about their products.

Driving a 50psi tire on a 35psi rim could yield a rather spectacular and dangerous failure.

I installed a receiver with more of an offset to lower the tongue a bit and that helped minimize the sway a some. Ground to the top of the ball is 14 1/2 inches which also gives the added benefit of raising the rear of the boat up for more clearance. The back end of the boat really hangs out there with no protection. I have seen some setups that have a small metal wheel under the rear of the boat to prevent it scraping the ground. I would think 6 ply or heavier tires would help steady the vehicle also.

I talked to one owner that had added the second axle and he said that it minimized the sway when a semi passes him.

The worst conditions I encountered were trucking down the road 70mph and a semi passes and whips in front of me just when another one comes up alongside and the turbulence from the front truck and the pressure from the one beside me really made the boat start a-rockin.

Another hairy encounter was driving though Atlanta Ga. The traffic was heavy and moving at a pretty good pace as it wound though the downtown area, kind of a white knuckle situation. I found out later that in order to move more traffic for the Olympics, they made the lanes very narrow so they could add more lanes. I heard on the radio that Virginia is now considering the same tactic on some of their roads!

Greg

I recently sold a 30' Jayco travel trailer I pulled with my Chevy Express van. I had a Hensley Arrow set-up. It worked really well. The van was almost more stable with the trailer. Check out the Hensley Arrow at http://www.nosway.com/. Wonder how well it would work on the Mac trailer? It is a good, solid product for rv's.

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The Hensley's strut bars that keep the orange hitch head longitudinally aligned would prevent the surge brake from working.

We have one on our triple-axle 34 Airstream, and love it.

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Moe

Good to know. Thanks Moe. The Hensley does work really good. When a truck went by on a two-lane highway we barely even noticed. It was also nice not to be having to take it on and off all of the time. Just set it - and forget it [with regular maint. of course].

jda

"Eliminating" trailer sway - as waternwaves would say "lol .... "

Guess my question should have been - does anyone tow a heavily loaded Mac, with fuel under the seats, using a Safari/Astro van without encountering dangerous sway at highway speeds?

I suppose I should sell my Safari and get the vehicle featured in the MacGregor video. Looked like the 1987 Taurus I used to own. As I recall, the marketing blather went something like - any family vehicle can tow these boats. As our friend would say lol ......

Thanks Chip for the 10 inch estimate. I suspect that Moe is correct stating that a different vehicle is the real solution but I'm not ready for that quite yet. I owned another trailer that had the suspension system welded to a short frame that was bolted to the trailer frame. This allowed the axle to be repositioned fore and aft. As you can see I am desparate.


Thanks everyone for the comments.

Normo,
Check the mods section. Don Johnson made this Trailer Damper System that looks like a pretty ingenious idea to reduce sway.

Greg

normo wrote:"Eliminating" trailer sway - as waternwaves would say "lol .... " Guess my question should have been - does anyone tow a heavily loaded Mac, with fuel under the seats, using a Safari/Astro van without encountering dangerous sway at highway speeds? ...

NO. It can't be done. Axle placement largely dictates tongue weight.

At least for my yr-2000 26X, the factory placed the axle (and therefore balanced the trailer) to some theoretically unrealistic gross weight (WHICH justified tires rated at only 3760). They know that any likely combo of motor + fuel + weekend supplies would "unbalance" the rig, reducing tongue weight too much. But, their attorneys probably believe they can't do otherwise.

I.E. if they placed the axle for the (now) commonly installed Suzuki 70 plus 18 gallons of fuel, then they would be tacitly granting that they are selling an under-capacity trailer. They couldn't balance the axle it to a "heavy" tongue weight either. That would mean their Taurus video was even more unrealistic than it already appears. Besides, with the boat selling at $14,990, they couldn't afford a new video.

Instead, they "enabled" the most likely installation to "counter-weigh" the tongue. The outboard+fuel levers across the trailer axle, unloads the hitch, lifts the rear bumper, and causes the tow vehicle to skate down the road like a newbie on ice skates. At least this way - it's MY fault for overloading the trailer. I love capitalism, but a healthy does of profit motivation mixed with an unhealthy dose of litigation ... and we end up with novice trailer rigs slip-slidin' their Fridays and Sundays across the Interstate system.

SOLUTION: Work-from-home on weekends, head for the lake on Monday