With the flatbed, just as any other trailer, you have to tie the boat down. I use those ratchet type tie down and criss cross from starboard beam to port frame of trailer, and vice versa, front and back.

I am usually pulling them with my diesel RV. While I can go about 85 with it, I usually travel at 60. Otherwise, the boats get covered with diesel soot and my mileage drops drastically. At slower speeds I get over 10 mpg.

With the car, I pull the trailex at whatever speed limits are + 5 mph. No problems yet.

Rick