nevertheless, willowleaf has a point
And not everyone who drives an SUV knows it has a higher CG and doesn’t drive, turn or stop like a normal car.
Driver education is not CD’s charge.
something even crazier:
Vehicles creating areas of low pressure and downforce sufficient to enable the vehicle to drive upside-down on a paved ceiling. First year of the Detroit GP they had to bolt the manhole covers down because the cars were sucking them off the manhole and into the air.
kayaks need aero aids
I heard click and clack talking awhile ago about the nightmare of transporting matresses on a cartop, and they were talking about inventing some sort of wing to keep it on the roof.
Quick: someone invent the kayak downforce wing, before Thule or Yakima do!
airfoil
http://goo.gl/RZKcmH
DIY project for your rack. Use cardboard templates for establishing correct curvatures onto roof then split rubber hose-see McMaster Carr - for bottom plywood airfoil.
I have a photo of an E250 airfoil using Quick n Easy mounting. Airflow goes over windshield then continues over airfoil. Solstice, Rendezvous and bicycle are generally out of the main flow.
Kayaks on SUV roof can act like Wings
Thank You for the many replies! Several of you were correct, I originally stated the Pungo was 38" wide and that is incorrect. I was guessing from the hip without taking the time to get the Pungo 120’s spec’s correct. Didn’t realize how many sarcastic kayakers were on this message board up until now -
All the more reason to paddle a canoe
Wrong shape, no lift 
Maybe
but I had a similar experience where I was transporting inner tubes inside a hatchback car. Since the hatch wouldn’t shut, it effectively became a wind foil and offloaded the suspension just enough to make the steering feel loose and sloppy.
It does not take a lot of air pressure to offload the front suspension - it isn’t as though there is sufficient force to lift the entire vehicle or offload the wheels - so I kind of believe that there is a configuration where boats could be aligned (especially if crooked on the roof) such that some suspension offloading could occur. Not saying it can happen, or would, but it’s plausible. In the vehicle I drove, after I shut the hatch, handling returned to normal. I’ll admit that a large open reach hatch (at 30-40 MPH) probably provides considerably more force than properly loaded (and aerodynamic) kayaks do. If the kayaks were not aligned parallel to the sides of the vehicle, however, this might change somewhat.
Any accident influenced (I won’t use the word caused) by such a configuration would be due to an overreaction by the driver to the altered feeling on the wheel and not due to any air pressures “lifting” the vehicle off the road or causing rollovers, since, as some have pointed out, the rack would likely rip off the roof long before this happened.
Many high profile vehicles are already a tad top heavy and have insufficient wheel bases to compensate for that weight. Some have very high sides and offer poor resistance to wind from abeam. Add this to a slightly underload on the front suspension and a less than calm driver, and I can see where such accidents might occur.
Rick
Regardless of what you say
Your boats didn’t cause what you experienced.
That is not sarcasm. It is fact
Jack L
You ask for advice
then you cherry pick the responses you like and label them correct?
Why did you bother posting. You are so wrong. Kayaks on the side do not generate lift.
I suppose that I don’t know much… Maybe haven’t transported boats… only for 30 years. Sometimes for pay… over 20, 000 miles a year.
agree with many…the OP needs more
time driving with boats on…chaotic wind(trucks…whatever) makes stuff on top create a squirrelly feel…with lighter vehicles can buffett the auto body around.
*Guideboatguy…with UL boats a wider strap the better for tight tie-downs, especially with hot temps & lots of sun hitting the hull.
How large
of a canoe do I need to strap to my F250 to get it airborne??
I figure upside down on the rack with the other end on the top of the tailgate the angle of attack is close to that of a jumbo jet at rotation.
Hmmmm. Maybe just more speed.
You did not understand what I wrote.
– Last Updated: Aug-11-14 5:16 PM EST –
When I commented on the deforming of the boat due to over-tight straps, I was asking the original poster to imagine how much worse that situation would be when the tension in the straps was enough to begin lifting a substantial portion of the car's weight. I guess I need to ask you that same question. Can you see that if the car were lifted by the boat, the straps would become incredibly tight, far tighter than you could ever make them when cinching them down yourself?
Basically, it was based on the same logic as my statement that the rack would fail if it were the means by which the car was lifted. I was trying to point out that none of these things (not the boat, not the straps, not the rack) are strong enough to lift the car without being wrecked. In short, this isn't something that could happen without there being plenty of damage to show for it afterward.
Thinking about rack strength again, how often have you seen Thule cross bars that are bent from overloading? I've seen that on several occasions (not from carrying boats, but from carrying construction materials, or from a big person standing or kneeling on a bar when working on a load). Thule bars are very strong, but the downward force which bent those bars was far less than the upward force that would be needed to take a fair amount of weight off the front tires. Clearly, if the rack didn't fail in some other way (and on any ordinary vehicle it would), the cross bars would bend. How many cross bars do you see with an *upward* bend? (Yeah, this last paragraph isn't a reply to BigSpencer, it's just preaching to the choir).
I also recommend wider straps
Smaller straps will break and you’ll fall out of the sky like a stone.
You need the 3/4 ton biplane glider
option.
Strap the watercraft on the truck crossways,so you have the wings sticking out over each side. You can stack them over each other, one resting on the truck bed sides, and one on the rack.
Then find a really big hill or small mountain, drive to the top, turn around, and let 'er rip. Updrafts on a warm day help.
Kits available here:
http://www.amazon.com/Woodshop-Biplane-Pick-Up-Truck/dp/B00CO8BXA2