[Paddlewise] Wind forces on roof mounted kayaks

I was hoping for some good input on what dynamic forces are really
working on the kayaks on the roof of my car.

There must be some engineering types out there that can calculate the
drag, lift etc. for kayaks moving through air.  I started thinking about
this when I saw someone traveling with a mattress on the roof of their
car.  Although is was tied on to the roof, at 55 it was NOT touching the
car at all!

My SUV has a notice that the "maximum load is 50 lbs. distributed
evenly" but my view is that at highway speeds (over 55mph) there may be
a stronger backward and lift vector working on my boats.  I travel with
the boats upright in saddles and it seems that a 50 to 70+ mph wind will
attempt to lift the boats out of the saddles and push them backward
possibly eliminating any downward force on the front saddles.

P.S.  I estimate that I may have traveled over 10,000 miles with my
boats on the roof and they have made it to all my destinations!

    Hal 

    Wilton, NH

    Power your boat with carbohydrates,
    not hydrocarbons.
         
          http://www.jlc.net/~hlevin


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