[tomhole]

With an open car hauler you can adjust the load to manage hitch weight. Although you don't want to get it too low, because the load is more aerodynamic, this allows a little lighter hitch weight as the natural aerodynamics of the load tends to provide a restoring moment, thus delaying or preventing the onset of sway. Same idea with a boat.

Tie a string to a paper airplane and put it in front of a fan. It stay pretty steady. Now tie a small box to the string and hold it in front of the fan. It bounces all over the place.

If the trailer gets really heavy, even with a boat or open car hauler, you should still use a weight distribution hitch. I think any hitch weight over 500 lbs should have a WDH, but that's just me. Keeps the nose down (and headlights in the right spot). Also, if the rear is down all the time, the brake proportioning valve gets cornfused and tends to use way too much front brakes with a heavy hitch weight.

So, anyone towing a travel trailer or box trailer should have sway control. Anyone towing something aerodynamic might get by without it.

Tom