Can you carry a single scull on a roof rack?

Do you know of any good guidelines for carrying sculling boats on the roof of cars with/ without a full sculling rack?  There has been an incident at our club as the bowball was tied down to the bumper and the strap worked loose and came undone and then got caught under a wheel as the car slowed down and wrenched the boat but tying the bowball down was an insurance requirement and I’m not sure how we prevent it in future?

Trailering – My advice is to always use a full sculling rack plus roof rack – the span on a car isn’t wide enough to support a single scull and you don’t want to break it.

I tie down the bow using a strap with a metal buckle that I position in front of the windscreen – i.e. not down near the bumper so I can see if it works loose.  I take the end of the tie and use electrical tape to wind it around so it doesn’t flap in the wind.

For the stern I just put the tie over the hull approx above the rear bumper of the car – it’s just a loop so not tied onto the boat and both this and the front strap are there to prevent the boat flexing up and down too much when the car is at speed.  These ties should be much looser than the ties over the roof /sculling rack i.e. they need to be able to move up and down 5 cms or so.

What do you do when transporting your single on a car roof rack?