A sheet of plywood
– Last Updated: Jun-10-09 12:52 PM EST –
makes a really big "wing". As for wind, I know, we use a 10ft log chain for a wind sock at the airport where I live. :)
Rack failure
The tops of Thule towers, and I believe also Yakima towers, are made to swivel on the base so as to be able to acommodate different roofline shapes. The part that the bar passes through is pop-riveted to the base.
Lacking a front tie down, if the rope or cam strap securing the hull to the front rack fails, a long boat will act as a sail if traveling at high speed.
The front of the hull will very quickly fly up, torquing the tops off of the rear rack towers, snapping the pop rivets, and the whole boat will fly off with the rear crossbar attached.
This is not theory. This has happened to multiple people.
I have square bars similar to Thule
so i may not be of much help but overall between Thule Js, Yakima stackers, Malone stackers, Malone Js and some thule hull down styles we prefer to use our older model Malone J racks. They conform to your boat on its side and hold it snug if you do your straps right.
We also wrap the strap on the js around the bar as a secondary safety measure. Next safety measure as the weakest point is our aftermarket (sheet metal screws by dealership) heavy duty rack (yeah right…)- we never go anywhere “not even short trips” without bow and stern lines which help support the rack, holding it down snug to the van roof.
On our bars on the trailer, we use 3 malone js and a malone stacker (not as strong) in the middle and this gives us maximum boats across the trailer when we use it. (sometimes we use the roof bars, depending on quantity of boats being transported) Again - bow and stern lines for added protection. Can never be too safe - Lots of lives on the road are at stake by driving near our boats on highways at high rates of speed and wind forces!!
Respectfully disagree
material thickness is not the only factor in strength.
I stand by my comment for most touring kayaks be they poly or composite. Race boats and surf ski’s should be cradled and or treated carefully.