When unloading a boat do not stop until the boat is completely off of the car. And when loading do not let anything interrupt you until it is completely strapped down.
Depending on the size and shape of the boat it need not be particularly light to blow off. In addition I’ve seen cases where a person had their boat partially strapped down or just on the rack when they stopped to help someone else. Coming back to their car they forgot to finish the job and drove off with catastrophic results.
In this case there were two errors. He stopped to help a friend and forgot to put on the front strap. He also did not use bow and stern tie downs. The result was when he reached highway speed the front of the kayak lifted up and tore the whole rack off of his car. This photo is after he retrieved the rack from the middle of the road and has it leaning on the side of his car. Fortunately no one behind him was hit or ran into the rack and kayak. Note that the rear cam buckle strap did not break.
I don’t know who is in the picture. Can’t be positive if he is wearing a PFD or something else slung over his shoulder. It’s fairly common for people to wear their dry suits on short drives on a cold day rather than put them on and take them off at the launch site. The picture and story behind it came from a paddling blog in Wales in 2014. The kayaker managed to borrow another boat to paddle that day. He was 15 minutes into a 30 minute drive.
We have been using this story and picture in a class we offer.