You may have heard horror stories of kayaks that have flown off the top of a car going down the highway, or of boaters who reach their destination only to find their kayaks damaged. The best way to keep these stories from becoming your own is to use the right equipment for your boat and vehicle type, secure the kayak the correct way, and periodically check on the boat during the trip.
Once you've loaded the kayak onto the roof, use pieces of foam to pad any abrasive surfaces that touch the boat and make sure the kayak is parallel with the sides of your car to reduce the effects of wind as you're driving. If you're using foam pads instead of a rack, place the boat upside down; otherwise set the boat in the saddles or j-cradles as instructed. If you're transporting your kayak right side up, use a cockpit cover to keep the boat from filling with water.
Use two nylon-webbing straps with spring-loaded buckles to attach the boat to your car. Put the straps as far apart as the rack will allow and fasten them snugly without over-tightening. Watch the kayak as you tighten the straps to make sure it isn't warping. After you've fastened the straps, lift gently on the bow of the boat -- the boat shouldn't raise at all. Then gently push the bow from side to side, and make sure the boat doesn't shift back and forth easily. If the boat lifts or wiggles easily, tighten the straps more.
Once you've strapped the boat down, use ropes to secure the bow and stern. Tie a rope around the front grab handle of the boat and attach it to a secure place on or under the front bumper of your vehicle. Tie another rope around the back grab handle and attach it to the back bumper. The ropes should put gentle downward pressure on the bow and stern of the boat. If you can't find a good spot to attach the ropes to your car, check the bumpers for a little square of plastic you can pop out with a screwdriver. Many vehicles have these little squares that have threaded holes underneath them and an eye bolt that screws into the hole. The eye bolt is often stored with the vehicle's spare jack, but you may need to order a second eye-bolt for the back bumper.
Tie off the loose ends of the straps and ropes to keep them from hitting your car or kayak, and then take to the road. After the first few miles of driving, pull over in a safe area and check the boat to make sure it hasn't moved, and check that the straps are still tight.
For more information on kayaking, see the links on the following page.