Once the boat is on the roof of the car and the straps are around the bars, pull the straps over the canoe or kayak to the other side of the canoe roof rack. It is quite common to see people throw the straps over the canoe to the other side. This is the best way to damage your car or even break a window on the other side. Admittedly, it can be tough to get the canoe straps over a large canoe.
If you are using long enough straps you should be able to pull the buckle side of each canoe strap around the front and rear of the vehicle, respectively, to the other side of the canoe roof rack. Then walk back around to the other side of the car and toss the free end over the canoe. Another way is to walk both sides of each strap around the car and over the canoe or kayak at the same time. Whatever the case you need to get the straps over the canoe or kayak. In the end you may need to resort to tossing them over.
