Here are some tips that may be helpful & handy.
Fasten kayaks on the car roof, a little difficult to reach? This is easy
Hang both straps on the opposit side of the first kayak.
Load the first kayak and throw over all straps. Beware the car! 
Fasten the loaded kayak, keep the two loose straps. Now load the number two. 
Throw the loose straps back over the second kayak, secure, check! 
With Troller you can pack the kayak some at home. Not TO heavy now. 😉
It can be difficult when you have to move the kayak last and first bit on the railing until you get it, some tips and you fix it.
Attach a strap to the rudder or somwere in the stern and you will get the power for the heavy bit.. 
The last bit when loading, place something on the front kayak holders so the kayak slides easily, when lifting a little in the stern and push, it will slide in place.
Take care of your things!
Prevent scratches, if the surfaces are llittle dirty put something between Troller and the car. Troller work just well anyway. Always kepp the strap to the roof rack taut.
Feel free to send in your tips for a simpler / smarter life. info.p-invent.se
