Trucking and the Environment
Aerodynamic Devices - Boat Tails
What are boat tails?
The term boat tail refers to a kit of extension panels or fairings that are mounted to the rear of a trailer for the purpose of reducing overall vehicle drag by reducing turbulence and pressure drop at the rear of the trailer. Current commercially available boat tails are fully extended while in use and fold back against the trailer doors when the driver wishes to back the vehicle into a loading dock and/or open the rear doors.
The boat tail works by streamlining the rear of the trailer. The air follows the panels off the boat tail around the rear corner instead of separating at the rear edge of the trailer. The suction drag on the rear of the trailer is reduced by deflecting the air inwards. This leads to a reduction in fuel consumption. However, little work has been performed to investigate the safety of these devices. Therefore, Transport Canada wished to study the possible aerodynamic gains of boat tails and determine which types of vehicles currently on Canadian roads would strike a boat tail in a collision before striking the CMVSS 223 rear impact guard mounted to nearly all van semi-trailers. Transport Canada therefore commissioned a study by the National Research Council of Canada to evaluate these possibilities. The executive summary of this report can be found below.