Actually in the video of Randy at Sunset point he was trying to stall right off the tail and the board didn't stall as dramatically as a wider tailed hard railed board does, it is too smooth for that so it just keeps on rolling. Also the displacement tail relies a lot on the fin for lift ( with soft rails and not much area in the tail it doesn't produce a lot of planing lift ) so needs to have a big fin as well as a lot of useable rail convergence in order to set the fin at the angles it needs to lift properly.. . . this again equals a narrow tail..
Surfboard design workshop: The displacement tail
Here's a quick introduction to the displacement tail design, in the 1940's they were know as 'sinker tails' but had not been fully developed as they still had square rails with hard edges and not much fin area.The displacement tail has to have ultra soft rails with no edges and should be really narrow. . . and thick. . . so that it can sink in and out of the water without catching or stalling.
Actually in the video of Randy at Sunset point he was trying to stall right off the tail and the board didn't stall as dramatically as a wider tailed hard railed board does, it is too smooth for that so it just keeps on rolling. Also the displacement tail relies a lot on the fin for lift ( with soft rails and not much area in the tail it doesn't produce a lot of planing lift ) so needs to have a big fin as well as a lot of useable rail convergence in order to set the fin at the angles it needs to lift properly.. . . this again equals a narrow tail..
Actually in the video of Randy at Sunset point he was trying to stall right off the tail and the board didn't stall as dramatically as a wider tailed hard railed board does, it is too smooth for that so it just keeps on rolling. Also the displacement tail relies a lot on the fin for lift ( with soft rails and not much area in the tail it doesn't produce a lot of planing lift ) so needs to have a big fin as well as a lot of useable rail convergence in order to set the fin at the angles it needs to lift properly.. . . this again equals a narrow tail..
