Does anyone know if there is a way to lock the roof rack to the roof?

I have a Yakimah ski rack for my FEH ... and the rack itself has reasonable locks, but they are kind of useless if the rack can be removed easily.

I'm not looking for something that will provide rock solid security ... but something that will slow someone down long enough that they will not bother trying to steal my skis because it would take too long.

Thanks!

david