Pack the luggage inside secure containers. One container is ideal but several are manageable if they are flat on the bottom and made for stacking. Fabric and hard-case containers are sold for rooftop storage.
Place the luggage containers on top of the roof and arrange the containers in a stable position. Utilize a wide stance to create an aerodynamic effect and reduce contact with wind.
Feed the end of a ratchet strap around the side railing on the roof. Hook the strap onto itself. Position to strap over the center of the luggage and hook the opposite end on the opposite side railing. Crank on the ratchet to apply pressure to the luggage and secure it to the roof.
Hook the end of a second ratchet strap to the cross railing on the roof. Attach the opposite end to the opposite cross railing and crank on the ratchet handle to tighten the strap. The two straps will create a cross on top of the luggage.
Add another strap in each direction to secure loose or odd-shaped loads on the roof. Push on the load in several different directions to test its security.
