Trailer Rear Devices
Devices that mount at the rear of trailers have generally been called boat tails or trailer wake devices. They modify the air flow as it leaves the trailing edge of the side and top surfaces of the trailer. The goal in all trailer rear devices is to reduce the wake field following the trailer, which can affect air some distance beyond the back of the trailer.
Many concepts have been developed to help get the air to wrap more efficiently around the trailer rear corners, reducing the size of the wake field and thus reducing the drag. First generation trailer tails showed some initial promise, but because of maneuverability and driver issues they did not gain widespread acceptance.
A new generation of rear devices are beginning to come into the market that address some of the deficiencies with the first generation products.